Showing posts with label CAN-Bus. Show all posts
Showing posts with label CAN-Bus. Show all posts

Saturday, December 26, 2020

Electronic Vehicle Architecture

Electronic Vehicle Architecture

The Electronics  Industry has had the fastest growth in the shortest amount of time, when compared to any other industry worldwide.  But before I expound on that, let me just say that, the invention of numerous mechanical contraptions during the late 1800s, like  James Watt's steam engine for example, started the transition towards new manufacturing processes which collectively gave rise to thIndustrial Revolution. Much later Samuel Finley Breese Morse invented the single-wire electric telegraph system and developed the Morse  Code. 

A bit of History

Sometime thereafter Alexander Graham Bell invented the first practical telephone system. Their's and the collective  efforts of so many others, without discounting anyone's  inventions and efforts, changed telecommunications forever. Ancient records show that  the first streets of Baghdad were paved with tar, that the Babylonians used asphalt to construct the walls and towers of Babylon.  The I-Ching even bears testimony to the fact that the cites of China used oil, extracted in its raw state some  2000 years ago before refining was first  discovered. Implying that the petroleum industry is not new, but that the current status of petroleum is a key component of politics,  technology and society today.

No tot digress, tar, crude oil and pitch, were used as a sources of fuel long before paraffin was even distilled from it. The thin distilled  paraffin was normally used as fuel for lamps whereas several hundreds of years later, the thicker residue was used to lubricate machinery. In and around the  time when oil/gas/fuel/petroluem was extracted from coal, Étienne Lenoir successfully built the internal combustion engine and innovated by Nikolaus Otto, who became famous for successfully developing the compressed charge internal combustion engine - the Otto engine.  

Assembly lines

Henry Ford on  the other hand wasn't an inventor nor an innovator as many have been led to believe, but he was rather a business magnate and a captain of  industry, who formed the Ford Motor Company, and sponsored the development of the "assembly line technique" for vehicle mass  production. One can therefore confidently say that their combined efforts, without diminishing any other contributor's efforts by the very least, over a period of some 200 years, are partially responsible for the social changes and economic development that shaped  societies that we live in today. This was  the infancy of the Automotive industry.

However, compared the Industrial revolution, modern day electronics would be equivalent to a Global Coup. Initially there was the  vacuum tube aka the electron tube, colloquially known as a valve. It gave way to the trusty transistor and discrete components which gave rise to the  analogue Integrated Circuit (IC) aka chip, followed by digital Transistor/Transistor logic (TTL) chips, followed by complementary  metal oxide semiconductors (CMOS), then digital semiconductors like ROM (digital read only memory), RAM (random access memory),  EEPROM (electronically erasable programmable read only memory), followed by large scale integration chips and VSLI (Very Large Scale  Integration Chips). 

Electronics and Software

With the advent of multilayer circuit boards and surface mounted technology, microcontroller SoC (system on a chip)  and microprocessors (µP) became pervasive. Assembler language was superseded by several high level languages for programmable chips and  software programming sat at the heart of most electronic devices and electronic systems. All of this happened in 50 years of electronics  as opposed  to 200 years of mechanical devices.

So you may ask, what has all this history to do with Volkswagen, Audi, Seat and Skoda and for that matter all other modes of transport  from plans to trains? Well the short answer, everything! Much like the Industrial Revolution with its mechanical ingenuity;  cars and planes were also predominantly mechanical since its inception, its mechanical ignition system was prone to imprecise ignition timing, resulting in improper fuel mixture burn, thus increasing its exhaust pollution. 

With the rise of telecommunications, so did  the electric wires, and electrically controlled gauges, relays and switches in cars and planes multiplied. The ever inflating cost of  gasoline then triggered the invention of CDI (Capacitive Discharge Ignition systems) which is in fact the first type of electronic  contraption integrated into the ignition system of a vehicle in order to, more precisely control its ignition timing, making it more  fuel efficient. 

These devices were available as add on kits and not produced as standard equipment in cars at the time. The preferred standard  equipment was the IDI  (inductive ignition system) and is the most common ignition system found on all cars built prior to 1980. It used a coil and distributor incorporating breaker points in its ignition system that was prone to ware-out due to arcing on  contact. During the 80's engines still used a coil and distributor to achieve dwell but it was somewhat computer controlled and by  the 90's the automotive computer evolved to ignition modules and the ECU, replacing the coil with a power pack. 

However, with the constant and  ever increasing price of gasoline and looming environmental concerns centred around vehicle exhaust pollution, the automotive  industry then accelerated its research and development into newer more compact fuel efficient power-train systems capable of higher  power output with enhanced robustness with a open policy towards alternative fuels.

New generation cars

So, by the 90's the Insulated-Gate Bipolar Transistor (IGBT) was introduced into the ignition system as discrete component connected  to the ECU called OBD - On-Board diagnostics. By 1993 the CAN protocol was standardized by ISO which led to its increased popularity  and adoption across the automotive industry.  By 1996 OBD had evolved to OBD-II and the discrete IGBT evolve into a IGBT module  integrated into individual coils itself. Starting from Y2k ignition systems were all ECU based but power packs were replaced by a  dedicated coil per cylinder, yet cloning the use of an Insulated-Gate Bipolar Transistor (IGBT) as discrete component connected to  the ECU. 

Communication Buses

From 2004 to 2010 the discrete Insulated-Gate Bipolar Transistor (IGBT) integrated into individual ignition coils evolved to a smart IGBT alongside the ECU.  The automotive ignition system had undergone a complete revolution which contributed significantly  to the system’s efficiency, exhaust pollution reduction, and robustness. By which time the use of wires had been minimized in  preference of a bus network which supported vehicle weight reduction and  vehicle cost. Copper wire have been replaced by fibre optic cable to facilitate faster communication. Some of the most important bus communication systems are CAN-Bus, Lin-Bus, MOST and  FlexRay.

Actuators and sensors, electronic control modules, Can-Bus and the ECU collectively facilitating Electronic Power Control (EPC) aka electronic throttle  control (ETC), Electronic Exhaust gas reticulation (EEGR), Electronic Valve Control (EVC), Electronic fuel injectors and so much  more, are just a small part of the overall influence that electronics have had on all vehicle engines. Other subsidiary programmable electronic  modules which are smaller computers in their own right now permeate cars, bikes, planes and boats, all connected together by at least three network systems. 

CAN-Bus is a multi-master twisted pair wire system reserved for high speed control systems like brakes,  whereas LIN bus is a single master, single wire system for low level communication for use by the rain sensor, sun roof, internal heating, and  the infotainment-bus, is a slow-speed system reserved for radio, GPS, internet communication, etc. Each system communicating with each  of its nodes in its provided protocol, each having different data transmission rates. By incorporating this level of electronics into cars, it has vastly improved stichometry and overall engine  performance, its economy, its driveability  and its safety besides reducing  emissions. 

Inept electronic knowledge

However, few mechanics know sufficient about electronics with its combinational logic, digital multiplexing, bits and  bytes, start and stop bits, fixed frames, software, etc to repair these cars packed with intercommunicating electronic modules. Even though scan tools have vastly increased their chances at successful repair, not knowing how to interpret fault codes further disadvantages them, not to  mention how frustrating it is for the vehicle owner who gets stuff around by incompetence. And here I’m even refereeing to the  "Automotive Technicians" employed by their respective automotive agents, who are more often than not incapable of repairing vehicles fitted with OBD-II. I'm quite sure there are several hundred if not thousands  of  VW owners who would concur.  How is it even expected for the DIY mechanic to fix it him or her self if the agents can't. Needless to say that  with continuous improvements comes great complexity and their successful  strategy to part us with our hard earned monies.

Diagnostic Trouble Codes abbreviated as DTC have been around for approx 30 years and is a component of OBD-II (onboard diagnostic system ver.2). These codes can be found stored  in the ECU's non-volatile memory for later retrieval by way of a scan tool. DTCs are displayed specific to the kind of problem that the system can or does detect from inside of a car engine/transmission, chassis, body or network.

Scan codes

In reality DTC codes can assist "automotive technicians", DIY mechanics and car owners to understand the problem with the car and possibly point them towards the nature of the problem or at the very least the system concerned. Bearing in mind many DTCs are generic but many of them are manufacturer specific and is best interpreted by consulting the car's manual.  Generic codes are defined by the EOBD / OBD-II standard and will therefore be the same for all car manufacturers.

But, let me break it down to for you. All diagnostic codes are alphanumeric as in P0XXX. It start with a letter followed by 4 numbers, as in P0303. This initial letter is P but can also be either B, C or U. They stand for Powertrain, Body, Chassis and Network respectively. The first numeral following the letter signifies whether the fault is generic of manufacturer specific. Since its a 0, its a generic code but if had a 1 then it would be manufacturer specific. The number 3  following the first 0 can be any numeral between 1 and 9. This number directs you to the subsystem of the car and is as follows.


Px1xx Air and fuel metering
Px2xx Air and fuel metering
Px3xx Ignition system and misfires
Px4xx Auxiliary  / additional emission control
Px5xx Speed control and idle regulation
Px6xx Communication /computer output signals
Px7xx Transmission
Px8xx Transmission
Px9xx Control modules, input and output signals

The final two numbers (xx) designate the individual components / sensors /actuator that threw the error. For example P0300 says, it's a powertrain error, it's generic in nature, it's in the ignition system and it's a random misfire. 

Whereas P0301 says misfire by cylinder No. 1,
Whereas P0304 says misfire by cylinder No. 4,
Whereas P0308 says misfire by cylinder No. 8,
Whereas P0312 says misfire by cylinder No. 12,

Likewise P0403 says, its a powetrain error, it's generic in nature, it's in the auxiliary / emission system and that the "Exhaust gas recirculation control malfunctioned"

Likewise P0501 says, its a powetrain error, it's generic in nature, it's in the speed control/regulation circuit and it's the "Vehicle speed sensor is out of range".

Like wise P0656 says,its a powetrain error, it's generic in nature, its in the computer/communication system and that its the "Fuel level output electrical sensor/circuit" 

Then there are also VAG specific 5 number numerical codes that coincide with P,B,C and U codes, like 16692 which coincides with P0308 (Misfire Detected on Cylinder 8)

And 17026 which coincides with P0642 (Knock Control Control Module Malfunction)

Saturday, September 19, 2015

LIMP MODE Q&A

LIMP HOME MODE

When I initially bought my VW Polo 2.0L she was a thrill to drive. Her speed was instant, cornering was really good and road holding never better. She was a joy to drive, very unlike my VW Golf II, but then I started getting car troubles,  which were many and varied. My first encounter with VW agents was a disaster. After they "repaired" my EPC fault they charged me a ridiculous sum of money, only to experience the same EPC problem the following day.  After speaking to several of their mechanics, who collectively were unable to fix my car, I came to realize  that I was either far more knowledgeable about automotive electronics than all of them put together, or they knew very little about electronics.  This just put me off the agents completely and when I took my Polo to independent mechanical workshops,  I found the same to be true. I still remember how lost I felt when my VW Polo went into limp mode the first time and the second and the third and the fourth. I felt lost, stuck on the freeway, late for meetings, frustrated and miserable because I couldn't repair her like I did the VW Golf II due to the fact that the Polo had OBD-II. I  thought my VW Polo to be unreliable, there was a point that I feared driver her at night, and later started to hate  even diving the Polo.  I was literally on the verge of setting her alight. But them I decided to buy a Ross Tech cable and downloaded their VCDS and my Polo is a joy to  drive once again. The rest of this blog is devoted to 10 vehicles owners who have experiences similar trouble with their VAG vehicles ranging from Drive by wire problems, to EPC trouble, to DTC trouble Codes to CAN-Bus-issues to name but a few. 

DRIVE BY WIRE
Steve sent this:- Had the problem of no power, tried the technique described in your blog (disconnect battery, wait, reconnect, turn ignition key, wait, turn off, turn engine on, wait, press throttle...) - and it worked beautifully. Many thanks for your help, very much appreciated - particularly as you've probably save me many pounds. 

QUESTION? - DRIVE BY WIRE
Anonymous sent this:- I have a '07 Polo 1.4 16v BUD. I don't have any lights on the dash, but the engine seems really weak through mid revs and is using a bit too much fuel. When I hook up my OBDII there are no faults recorded but when I view the throttle position in real time it doesn't seem to open in a linear manner. As I press the pedal on the road, the throttle valve seems to open slower than the position of  the pedal. eg; 50% pedal = 30% throttle position, 80% pedal = 35% throttle, 95% pedal = 40% throttle, 100% Pedal = 100% throttle. As you can see WOT does give WOT at the throttle body, but I don't generally drive with my foot planted on the floor. I am confused why it does this as you would expect the throttle body to open the same amount as the pedal, could it need alignment? I am loathed to take it to the VW dealer for fault diagno$i$ so if anyone has any ideas????  Thanks 

ANSWER!
On drive by wire model vehicles the throttle doesn't open like legacy cable throttles because its electronically controlled. 

DRIVE BY WIRE
Durell  Dunn  left this:- I am currently experiencing the same problem with my 2003 polo,1.4. The car goes into limp mode and on some occasions switches off in traffic, hectic ! I will use your method. Thank you for saving me from going to a VW dealership, all I can do at this stage is do and hope 

DRIVE BY WIRE
Loci sent this:- Hi. I have a problem with my Volkswagen Polo 1.4 Tdi. It seems to have a good start but after I drive for around 35 minutes it loses the power so I could not pass 2000 giro. Thank you for your suggestions.

QUESTION? - DRIVE BY WIRE 
Anonymous asked:- My car is a polo 1.4 2012 model. When I start the car the EPC light switch on then I put gear to move the car but it limbs then I switch it off then start it again then the EPC light does not switch on then off I go... What could be wrong? 

ANSWER!
The trouble can be one of many things, among which are your accelerator pedal, throttle body, knock sensor, Fuel pump pressure, even a loose fuel cap. You need to check through each systematically but for that you at least need a scan of your vehicle.

ENGINE LIGHT COMES ON
Lee Kyprian left this:- Everyone who has ever owned a car has experienced the confusion and even panic which can arrive when your check engine light suddenly comes on.

QUESTION? VW ELECTRONIC POWER CONTROL
Abror Isoqov sent this:- Hello. My car is VW Golf 1.6 16v and I have a problem with acceleration it has no enough power. It accelerates very slow and at 5th gear it can get max 130 km/h. At neutral position when engine gets about 5000 rpm the EPC light comes on. After restarting the engine it goes off. Tester didn't determine any trouble codes. What can cause for this problem. I went about 7-8 auto services but any of them could help. But I didn't go to VW dealer because it will be very expensive. last time they charged me $125 just for diagnostic.  Please help me with this issue.   

ANSWER!
What you explaining is limp mode and everything else seems very odd. Because by the time the EPC light does go on, a DTC is already set which any scan tool should be able to retrieve. Unless there is a problem with you DLC wiring, so that communication between vehicle and scan tool is erroneous.

VW ERROR CODES
Steve Cain sent this:- Hi, vw polo 1.4tdi 2003, AMF engine code,  problem is that when driving at any speed, car looses all power, engine stuck on 1200 rpm, throttle pedal no response, glow plug heating light flashes, switch off & switch back on straight away, car drives normally, no warning lights. Can you shed any light on this problem, (driving my wife mad). Thanks, Steve 

ANSWER!
I have covered this problem quite substantially in previous blogs and it in your interest to ready through them.

WON'T REV
Anonymous sent this:- My VW Jetta 2002 1.8t stopped me on the highway and it refused to rev and the mechanic says it is the brain box. I don't understand is he correct?

ANSWER!
Yes he is correct, problem lies in the ECM circuit but not necessarily the ECM itself. Dude you need to get your car scanned to get a better idea of  the actual problem.

CAN-BUS
Hi! I read your blogs and saw writings from you  about the CAN bus protocol. I have a problem to understand something on my cars OBD connector and the CAN bus line. Can you please help me maybe? Can we talk about? When I connect my 2 channel  DSO to the OBD connector pin 6 and pin 14 ( CAN-H and L ) and pin 5 (GND) on my VW Polo 1.4D year 2003 I got this signal what I posted right now. But, when I do the same think on my Renault Clio 1.5DCI year 2003 I got the right CAN signal.  

ANSWER! 
The likely hood is that your VW Polo isn't CAN compliant because its still a 2003 and used KWP-1281 and KWP-2000 protocols.  All VW's after 2008 is fully CAN compliant.

Thursday, June 11, 2015

AUDI EPC LIGHT PROBLEMS


AUDI EPC LIGHT

It is common knowledge that EPC light problems have been haunting Audi drivers incessantly for the past few years, announcing itself on Audi A1,  Audi A2, Audi A3,  Audi A4,  Audi A5, Audi A6,  Audi A7,  Audi A8,  Audi Q3,  Audi Q5, Audi Q7, the Audi RS4,  Audi RS6, Audi RS8, Audi R8, Audi S4, Audi S6, Audi S8 and Audi  TTs even before they're run-in. Several Audi owners are dismayed that EPC problems present themselves on virtually new cars. 

In fact, EPC problems pop-up at any time, on any Audi new or old fitted with X-by-Wire technology. Any Audi  without a throttle cable, is naturally fitted with a full Drive-by-Wire system which is supervised by the Electronic Control Circuit (EPC)  / Electronic Throttle Control (ETC)  that turns on the dashboard mounted EPC (K132) indicator light when it detects a malfunction, then registers Diagnostic Trouble Codes (DTC)  in the ECM memory.  Even though the EPC light turns on exclusively for  non-emission related faults, it does however turn on along with the MIL for emission related faults. 

The EPC  / ETC is a torque monitoring circuit and monitors for torque discrepancies and torque inefficiencies and when it detects one, sends the vehicle into emergency running mode (limp mode). These are prevalent when towing, when driving up an incline, when in manual mode, when in cruise control, after spirited driving, etc, and may even cause the ABS, ESP   lights to came on. Some drivers, assume  that it's happening more frequently over time and others are concerned that the EPC trouble are going to get worse because of its  randomness. But this is not the case. 

Bear in mind that once the EPC light is on, no other EPC related fault is going to make it glow any brighter. Once it's on, it's stays on even if the battery is disconnected, and it will come back on when you reconnect. However, the ECU will monitor the EPC circuit and if the same error does not occur in three successive trips of at least 7 kilometers, it will erase the DTC and it would seem as if it never happened, until the next time.  These are safely features specific to Drive by Wire systems and their workings can be viewed in the adaptation groups when retrieving errors with a scan tool.

ADAPTATION GROUPS PERTAINING TO EPC

Group 60 -- Throttle Valve Adjuster / Adaptation Epc-system
Group 61 -- Epc-system / Throttle Valve Adjuster (System 1) 
Group 62 -- Epc-system / Throttle Valve Adjuster (System 2)
Group 63 -- Kickdown Function
Group 66 -- Cruise Control Status

AUDI EPC LIGHT RELATED DTC

18039 / P1631 - Accelerator Position Sensor (G79): Signal too High 
18041 / P1633 - Accelerator Position Sensor 2 (G185) Signal too Low
18042 / P1634 - Accelerator Position Sensor 2 (G185): Signal too High
18047 / P1639 - Accelerator Position Sensor 1/2 (G79/G185): Implausible Signal 
 00777 - Accelerator Position Sensor (G79): Implausible Signal

No response from the throttle even with your foot flat on the accelerator pedal.. There are two potentiometers fitted to the accelerator pedal which are monitored by the ECU and when it it detects an intermittent signal from one pot, it turns on the EPC light then uses the second pot for acceleration but it is limited. When both pots detected as are intermittent, EPC light goes on and engine only runs at idle speed. When this error occurs, turn the engine off, stomp on the accelerator a few times through its full travel.  It could just be specks of dust that settled on the one of the potentiometer (variable resistors) tracks that stymied the ECU for a few millisecond or so. I this happens often and thereafter, presenting a 18047 / P1639 or 18039 / P1631 or 18042 / P1634 or 18041 / P1633 then consider replacing the accelerator pedal.

No response from the throttle even with your foot flat on the accelerator pedal. There are also two redundant potentiometers in the throttle body that determines the throttle valve angle and it has three modes of failure. One for when the valve angle sensor fails, one for when throttle valve actuator (motor) malfunctions and one for when throttle valve position is cannot be recognized by the ECU. When this happens  the ECU shuts off the voltage supply to the actuator, causing the throttle valve to defaults to mechanical stop position and the engine speed is limited to 1200 RPM. If any of the DTC fault below show up in your scan, check the 6 pin plug interfacing with the throttle bodyIt would be best to redo adaptation thereafter before thinking of replacing the throttle body. 

000289 / P0121- Throttle Position Sensor (G69): Implausible Signal - Intermittent
16506 / P0122 - Throttle Position Sensor (G69): Signal too Low - Intermittent
17987 / P1579 - Throttle Actuator (J338): Adaptation Not Started - Intermittent
17976 / P1568 - Throttle Actuator (J338): Mechanical Failure 
17972 / P1564 - Throttle Actuator (J338): Under-Voltage during Basic Setting 
17952 / P1544 - Angle Sensor 1 for Throttle Actuator (G187): Signal too Large - Intermittent
16606 / P0222 - Angle Sensor 2 for Throttle (G188): Signal Too Low - Intermittent
000547 / P0223 - Angle Sensor 2 for Throttle (G188):Signal Too High - Intermittent
17581 / P1173 -  Angle Sensor 2 for Throttle Actuator (G188) Signal too High 
18042 / P1634 - Accelerator Position Sensor 2 (G185): Signal too High 

You have difficulty starting but eventually does start but idles very rough, bucks and surges when you attempt to drive it. The   EPC, MIL (Check engine light)  and ESP lights come on. This is most likely caused by the Injectors  N30-N33 or the Ignition Coils N (1st cylinder), N128 (2nd cylinder), N158 (3rd cylinder) and N163 (4th cylinder) since both the Injectors and Ignition coils causes exactly the same symptoms. It also   exhibit the following DTCs.

17633 / P1225 - Fuel Injector for Cylinder 1 (N30): Short to Ground  - - Intermittent
17634 / P1226 - Fuel Injector for Cylinder 2 (N31): Short to Ground  - - Intermittent
17635 / P1227 - Fuel Injector for Cylinder 3 (N32): Short to Ground  - - Intermittent
17636 / P1228 - Fuel Injector for Cylinder 4 (N33): Short to Ground  - - Intermittent

MORE EPC PROBLEMS

J757 Engine Component Power Supply Relay cause loss of  high-pressure and turns on EPC. ESP and MIL lights.

N75 Solenoid valve for charge pressure limitation and turns on the  EPC and MIL lights but shown no symptoms of failure except go into limp mode. 


Audi A1, Audi A2, Audi A3, Audi A4, Audi A5, Audi A6, Audi A7, Audi A8, Audi Q3, Audi Q5, Audi Q7, the Audi RS4, Audi RS6, Audi RS8, Audi R8, Audi S4, Audi S6, Audi S8 and Audi  TTs EPC Problems.

Thursday, March 7, 2013

WHY ENGINE LIGHT COMES ON


EPC LIGHT


Seeing a VW or a Volkswagen or Polo da Volkswagen or a VAG car or a new Polo on tow,  is becoming an all too familiar site, - view picture below. VW cars are seen piggy-backed and carried to service centers on a daily bases because VW owners are encountering serious trouble with their Volkswagen cars.  
Many Volkswagen drivers are often stranded on the high ways or freeways whilst driving to and from work because their VAG cars are throwing tantrums, by going into limp mode and turning on the EPC light.  Most VW drivers have no idea why engine light comes on. 

I've been late for  meetings on several occasions because of this. On a few others, I couldn't make it to the  bank in time because the Electronic Power Control -EPC- circuit incapacitated my VW Polo Classic 2.0L Highline. The worst was when I took my daughter to the dialysis clinic and the Electronic Power Control (EPC) light came on, because I ran over a speed bump a little too fast. This resulting in "Limp Mode" causing my daughter to be substantially late for her dialysis session. This could have been a life or death situation but fortunately it wasn't.

I took this photo with my cell phone. The picture quality really isn't good, so therefore the
Bluemotion badge 
to the left of the right side tail light  isn't clear at all.  But I couldn't pass-up
the opportunity to capture a 
VW Bluemotion 2012 loaded on a roll-back.

Anyway,  lets look at why this very risky and inconvenient issue haunts most VAG car owners. All Drive-by-Wire cars (since 2000) has an Electronic Power Control (EPC) light. The EPC dashboard warning lights are not exclusive to VW or VAG cars but affects most other new cars regardless of its manufacturer though the common denominator is Drive-by-Wire and an Engine Control Unit (ECU) often called the Powertrain Control Module (PCM) with an embedded microcontroller supplied by the same manufacturer.  EPC stands for Electronic Power Control which is controlled by the ECU (Engine Control Unit). In essence the Engine Control Unit (ECU) is a microcontroller with associated circuitry which control the sub-modules in the car, all connected together by either OBD II or CAN-Bus. Certain outputs from these sub-modules can activate the Electronic Power Control  circuit, especially if the reason for sending its signals to the ECU (Engine Control Unit)  could cause damage to the engine or is a danger to the passengers. For example, if the car runs out of oil, or if the emissions exceed the prescribed level, or  if  the car hits a speed bump a little to hard or if a brake bulb fails.

In the first case the oil level sensor will detect that the lack of oil in the crankcase and since there is a possibility the engine may seize-up, it sends a pulse train to the PCM to activate the Electronic Power Control (EPC), which cuts the power to the engine, making the car go into "Limp Mode" and switching on the EPC warning light. In the second case the lambda sensors on either side of the catalytic converter  will detect the fuel rich exhaust fumes and send a pulse train to the PCM to activate the Electronic Power Control (EPC), which cuts the power to the engine making the car go into "Limp Mode", thereby limiting carbon pollution and  and switch on the EPC indicator light (epc warning light) . In the third case the engine knock sensors will detect the suspension knock as the car hits the speed bump and will send a pulse train to the PCM to activate the Electronic Power Control (EPC), which cuts the power to the engine making the car go into "Limp Mode" and switch on the EPC dashboard light. In the fourth case, one of the Electronic Control Unit or Body Control Modules (BCM) sensor will sense that a brake light is open-circuit, send a pulse train to the PCM to activate the Electronic Power Control (EPC), which cuts the power to the engine  making the car go into "Limp Mode" because in that condition the car is not roadworthy. The EPC dashboard light is a very graphic demonstration that there is something amiss in you VAG that needs to be remedied.

There are several other sensors strewn throughout the car and many of them can have an effect on the Engine Control Unit (ECU) and cause the EPC light to come on. Sometimes when the EPC fault light comes on, it may be a spurious error, based on past driving cycles. A driving cycle is calculated from the time the engine starts and drives -which should be a min 5 minutes- until the engine is switched off. It could  take three drive cycles to clear a spurious error but if the fault persists it has to be diagnosed on a VAG-COM diagnostic tester.

Should you require more information on,  what is epc light, what is a epc light, vw epc warning light, vw epc code, epc on a vw, epc warning light vw, epc vw tiguan,  epc on jetta, epc light on, what is the epc light,   epc fault light, checkout epc-demystified.

Here are some Non  Volkswagen Websites I highly recommend,  
http://electroniques.blogspot.com
http://photojani.blogspot.com
http://expowp.blogspot.com  

Thursday, February 7, 2013

VAG


VW DIY

In the not so distant pass, whenever something went wrong in your VW, Polo, Jetta, Passat,  AudiSeat or Skoda,  you could do one of two things. Either  take it to a VW specialist to have it checked out or you could fix it yourself, if you are a hands-on, DIY kind of person. Nowadays the latter option has faded away into obscurity. With the stream of problems VAG cars are having, many of us are in the dark regarding repairs. We make educated guesses, replace parts by substitution, often costing huge amounts of money for repairs and the fault still persists. Below I have out-lined some of the problems I have encountered and with any luck shed some light on the problems you've been having with your VAG car. But before I go any further you may be itching to ask "What is a VAG car?"

Well, VAG stands for Volkswagen-Audi GMBH in Germany, also refers to Volkswagen Aktiengesellschaft or Volkswagen AG for short and Volkswagen-Audi Gelelschaft (Geleslschaft means Association). In essence, it's the same, exact and identical  group. And any car manufactured or sold by them is referred to as a VAG car. Amongst these are, VW, PoloJetta, Passat, Audi, Skoda, Touran, Tauareg, Beetle, Tiguan, Golf, PorscheAmrok,  RabbitBentley, BugattiBora, Phaeton, Vento, Kombi, Transporter,  Lupo and the  Lamborghini, each one with a different engine with varying capacities with obscure three letter abbreviations like, BBX, AAF, AEX and APE amongst many others. However many of them have the same or similar Electronics Bosch Motronic system hardware with software ranging from ME 5.x to ME 7.x, with several support modules in common, networked to the OBD II / OBD2 (On-Board Diagnostic System ver. 2) or Can-Bus (Controller Area Network) standard.

The VW Polo 2007 with new Bluemotion technology can switch its engine off
when it comes to a halt, yet plagued by the legacy VW EPC light problem.

The idea behind this is so that only the  Volkswagen dealership technician are supposed to do the servicing and perform repairs to your car. The VW car manuals specifically discourages anyone other than qualified or trained mechanics /auto-electricians and technicians or mechanicians to perform servicing, especially changing codes and performing readiness testUnder the OBD II and Can-Bus standard, an ECU (Engine Control unit) interfaces with various other modules fitted in the car and controls and manages all sub-circuits. For example, Central Electronics Module, ABS module, Temperature Control Module, Speed-o-cruise Module, etc... When one of these modules detects a fault with one of its components, it registers a error in the non-volatile memory. Lets say you have a front wiper motor problem and it just wont work, but the fuses are OK. Even if you suspect the wiper motor as faulty and it actually is faulty and you replace it, the new wiper motor still wont work after its been replaced and switched on. You first have to clear the error or errors  from non-volatile memory with a diagnostic tool. Then and only then will it work.  

I've had the same results with my power steering which just wouldn't work after some work was done to my car and in the process the Power Steering Motor was disconnected. When it was reconnected the power steering was very stiff and difficult to steer. After going through the entire process of checking and back-tracking it still didn't work. Eventually, when the diagnostic tester was plugged in, two errors codes showed up. The first indicating that the +30V supply had dropped to an unreliable level and the second a power steering error. The first was because the battery was disconnected and the second was because the power steering plug was disconnected. After erasing the two error codes from the non-volatile memory, the power steering work perfectly normal.

I can assuredly say that I am not alone or rather that my car trouble is not unique, neither am I the only VW owner having car trouble (see previous blogs).  It appears that my 2007 Polo Classic Highline shares most of the problems listed below with my fellow VW owners. There are probably hundreds if not thousands of other  VAG car owners experiencing the same issues with their cars as I am experiencing with mine. Here are just a few of the problems that my fellow VW owners shared with me :-

"VW polo dashboard brake light stays on" / "EPC instrument fault indication light is on" / "VW polo warning lights on dashboard" / "VW  polo classic is showing epc light, starting and dying" / "polo dashboard controls" /  "VW  polo warning lights off power steering" / "warning light on dashboard" / 2007 volkswagen polo problems" / "audi electronic power control indicator" / "won't rev" / "VW Polo EPC Warning Light" / "golf mk4 dashboard warning lights" / "epc instrument fault indication" / "VW  door key problem" / "VW  polo accelerator position sensor (g79)" VW throttle body sensors"

NB! Fellow VW drivers found this site to be helpful and was interested in checking out the following sites as well.

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Wednesday, January 30, 2013

VW ELECTRONIC POWER


EPC LIGHT EXPLAINED

As I mentioned before in my older blogs, the new generation of VW cars are designed to turn on an EPC Light (not check engine light) so that only the  Volkswagen dealership service technician or technicians are supposed to do any an all servicing and repairs.  The VW workshop manuals specifically discourages anyone other than a qualified or trained mechanics / auto-electrician and automotive technician to perform servicing, especially changing codes and performing readiness test.  This is because  incorrectly set readiness and adaptation settings can completely disable your car and virtually render it useless. To repair it would then cost a small fortune.

CHECK ENGINE LIGHT

An earlier blog, covers some late model VAG cars with fuel injection and electronically controlled throttle body instead of the traditional accelerator cable controlling the throttle valve. It is called Drive-by-wire or DBW for short. When the Engine Control Unit -ECU, which invariable is a computer in its own right detects a fault  Diagnostic Trouble Code - DTC  in the Drive-by-wire system, it registers a fault Diagnostic Trouble Code - DTC in its non volatile memory and turns on the EPC light, disables the accelerator and throttle bodylimit the engine to a maximum of 1500 rpm -"Limp Mode".  This would be sufficient power to "Limp Mode" the car to a service centre without causing further damage to the car or unduly polluting the air should the fault cause it to smoke. This is a safety precaution and can be equated with, what would happen if  an accelerator cable got stuck in the downward position. Disaster could follow. The Engine Control Unit -ECU collects faults Diagnostic Trouble Code - DTC from all senders and stores an internal list, which is only visible with a diagnostic tester. Diagnostic Trouble Code - DTC can range from excessive emissions to - intermittent air bag connections, from brake light failure to - depleted brake pads, from interior ultrasonic failure to - immobilizer problems to even disconnecting the battery. Each of these faults generates codes, some of which can be viewed in future blogs.

Should the Volkswagen Engine Control Unit -ECU  considered a Diagnostic Trouble Code - DTC to be so serious that it could possibly do harm to the engine or the environment, it will inhibit the throttle function and limit the engine revs or even disable starting or idling completely.  Unfortunately the only way to repair such problems, is to connect the  Volkswagen Golf,  Jetta, VW Polo, or Volkswagen Beetle, to a dignostic tester through its CAN-Bus / OBD2 / OBDII port and view  Diagnostic Trouble Code - DTC  if any and  Diagnostic Trouble Codes, clear them from memory and perform corrective procedures.  Below is an overview of the Electronic Power Control Circuit - EPC and how the Drive-by-wire system operates.
The basic operation of  the Electronic Power Control (EPC) Schematic showing inputs
from drive-train sensors and output signals to drive-train actuators.

Other INput senders could result in similar problems. For example - the Oxygen Sensor could detect that the exhaust fumes carbon mixture exceeds the prescribed level which is toxic to  the atmosphere and the environment. It could disable driving of the vehicle by enabling the Electronic Power Control Circuit - (EPC), turning on the EPC warning light or even disable starting not allowing the car to idle. This could be due to a dead plug causing the idling to be erratic and not burning up all the fuel. This un-burnt fuel will invariably change the exhaust fumes composition which triggered the Catalytic Converter and Oxygen Sensor in the first place.

Like wise, when the brake light bulbs blow or the fuse to the brake circuit blows, an INput signal from the brake light sender could also activate the Electronic Power Control Circuit - (EPC), turning on the EPC warning light causing the car to go into "Limp Mode" because driving a car on a public road without brake lights is an accident just waiting to happen. In fact the Engine Control Unit (ECU) looks upon this car as non-roadworthy as a safety procedure. In a previous blog I described an Electronic Power Control Circuit - (EPC)which switches on the EPC light problem caused by an INput  signal from one of the knock sensors with the same results as above. Other senders INputs that can cause similar problems are:-

The Engine Speed Sender G28 situated at the flywheel.
The Hall Sender G40 situated at camshaft pulley
The Hot Air Mass Meter G70 and intake Air Temperature sender G42 situated near intake manifold.
The Lambda probe G130 situated upstream of catalytic converter
The Lambda probe G39  before catalyst converter
The Knock sensor I - G61 below intake manifold
The Knock sensor II - G66 below intake manifold
The Accelerator Position Senders G79 and G185 embedded in accelerator pedal (EPC Problem)
The Clutch pedal switch F36 situated in the drivers foot well.
The Brake light switch F and brake light switch F47 situated in the drivers foot well.
The Throttle control valve / motor drive assembly  J338 
The Angle Senders  G187 and G188 situated inside throttle body.
The Fuel Pressure Sender -G247

NB! VAG car owners who found this site to be helpful 
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