EPC DEMYSTIFIED CONTINUED 2

Continued from EPC DEMYSTIFIED CONTINUED 1.

  ...  I only became aware of this when my EPC light went on due to the knock sensor. See picture blog.  More...

 PART 3

BREAKING THE CODE

What needs to be mentioned as a basis of understanding, is that OBD (on-Board Diagnostics) was introduced in the 70's along with CDI (capacitive discharge ignition systems) as DIY kits. Few cars had fuel injectors, points and coils were fast being taken over by electronic modules. During this time some standards were introduced but they were not very well defined and as such manufacturers developed their own and applied their specific systems and developed their own code descriptions which later became known as OBD1. This was considered undesirable and counterproductive since none franchised service, and general mechanical repair centers had to purchase different scan tools, interface cables and connectors, skills and manuals for each make and model of car they specialized in. This resulted in vehicle diagnostics becoming unwieldy expensive. In February of 1986, Robert Bosch founder of Bosch, introduced the CAN (Controller Area Network) serial bus system to  the Society of Automotive  Engineers (SAE) in motor town of Detroit.

This influenced the  Society of Automotive  Engineers (SAE) who subsequently drafted a list of standards and practices that aught to be implemented by all automobile  manufacturers and recommended them to the Environmental Protection Agency (EPA). The EPA weighed-up these standards and recommendations, acknowledged their benefits, and adopted them. The standards criteria included a precisely defined diagnostic connector for each auto manufacturer, a standard scan tool and a common electrical communications protocol and a common data format, and the ability to monitor other
vehicle parameters. Lastly that the standard scan tool should interface with vehicles of all manufacturer. It also included mandatory definitions and descriptions for certain emission control system  defects which was labeled the ‘P0’ Codes. Manufacturers were allowed to generate and use their own ‘manufacturer specific code descriptions’ known as ‘P1’ Codes. This collaboration of standards became known as OBDII, (OBD2) and was adopted for implementation by January of 1996. Two types of scanner codes, namely manufacturers codes like VAG codes and SEA Codes are now the standard practice.

OBD-II  

As mentioned above, Powertrain Control Module (PCM) error codes are assigned the prefix P and pertain to the, Engine management, Transmission management, Fuel Pump and Gasoline Management, Automatic Transmission – Hydraulic Control, Emission control system, evaporative emission purge control (HVAC), Auxiliary module management and other some 0n-board Hybrid application.  For example P1340  suggests that the Powertrain triggered a DTC and describes it as an "Crankshaft-/Camshaft Position Sensor Signals Out of Sequence"

From the above example it would thus be easy to interpret the DTC below relating to EPC (Electronic Power Control)

DTC (VAG)   DTC (SAE)  Society of Automotive  Engineers

16504 P0120 Throttle Position Sensor A - Circuit Malfunction
16505 P0121 Throttle Position Sensor A - Circuit - Performance Problem - Out of Range
16506 P0122 Throttle Position Sensor A Circuit - Low Voltage Input
16507 P0123 Throttle Position Sensor A Circuit - High Voltage Input
16894 P0510 Throttle Position Sensor - Closed Switch- idle micro-switches -F60 malfunctioning
17951 P1543 Throttle Actuation Potentiometer - Signal too Low
17952 P1544 Throttle Actuation Potentiometer - Signal too High
17913 P1505 Throttle idle micro-switches -F60 not/short-circuit opens
17914 P1506 Throttle idle micro-switches - Switch Does Not Open/Short to Ground
17988 P1580 Throttle Actuator (B1) Fault - May be caused by low battery if found with 16487 (P0103)

18038 P1630 Accelerator Pedal Position -G79 signal too small  (low)
18039 P1631 Accelerator Pedal Position -G79 signal too largely (high)
18040 P1632 Accelerator Pedal Position -G79 supply voltage malfunction
18041 P1633 Accelerator Pedal Position -G185 signal too small
18042 P1634 Accelerator Pedal Position -G185 signal too largely
18047 P1639 Accelerator Pedal Position 1+2 Range/Performance -G79 and -G185 implausible signal
18048 P1640 Internal Controller Module defective (EEPROM) Error

EPC Circuit.

The EPC  circuit consists of a number of disparate components that control and supervise, regulate and determine the throttle valve position at all times. They include;

1) the accelerator pedal position sender (TP sensor G69)
2) the accelerator pedal position sender -2, (G185)
3) Black 6-pin plug with 6-pin with Gold plated contacts

NB! The above three components are part of the accelerator pedal.

4) the throttle valve control module (unit),
5) the K132 EPC fault lamp, (electronic throttle control fault indicator)
6) the engine control module (unit).

Firstly we going to do a test on components 1, 2 and 3 above. To do this test, you need a Fluke multimeter or similar for a voltage and continuity / resistance test. Unplug the 6-pin plug from the accelerator pedal and switch on the ignition. Connect the multimeter and check for a 4.5 volt reading between;-

pin 1 and ground, then between pin 1 and pin 5
Pin 2 and ground, then between pin 2 and 3.
If tests prove to be "OK", switch ignition off.
Do additional checks for short circuits between one another and ground and if this checks "OK",

Locate the ECU, normally inside cowl. Disconnect the ECU from its socket, identify pins 34 & 34, 35 & 36, and 72 & 73 on the socket. Disconnect the 6-pin plug from the accelerator pedal once again and check for continuity between this plug and the ECU socket. There should be continuity between pins:-

1 of the 6-pin plug and pin 72 of the ECU socket.
2 of the 6-pin plug and pin 73 of the ECU socket.
3 of the 6-pin plug and pin 36 of the ECU socket.
4 of the 6-pin plug and pin 35 of the ECU socket.
5 of the 6-pin plug and pin 33 of the ECU socket.
6 of the 6-pin plug and pin 34 of the ECU socket.

Any resistance above 1.5ohms should be investigated for corrosion. This often causes the engine to surge (idle unevenly or rather breaths) However, if this test proves "OK" and no wiring malfunction is detected, replace G69 and G185 (single unit) on the accelerator pedal. NB! these components are non adjustable and needs to be replaced as a whole.

When the ignition is turned on, the ECU checks all EPC components necessary for the proper  functioning of the Electronic Power Control. If a malfunction is detected in the EPC (Electronic Power Control) system whilst the engine is running, the ECM will simultaneously activate the EPC (Electronic Power Control) warning light and make an entry of this malfunction in  the ECU (electronic Control unit) DTC (Diagnostic Trouble Codes non-volatile memory.  By a process of eliminate the EPC fault can be fixed.

The list below categorises VW and Audi manufacturer predetermined data groups which varies depending on the vehicle, year, engine, engine code and management system on board.

Group Number / Group Category

1–9     General engine activity data
10–19 Ignition data
20–29 Knock control data
30–39 02 sensor control system data
40–49 Three-way CAT data
50–59 Engine speed control data
60–69 Throttle drive data
70–79 Emissions reduction data
80–89 Special function data
90–97 Power increase data
98–100 Compatibility data
101–109 Fuel Ignition data
110–119 Boost pressure control data
120–129 Control unit communication data
130–150 Special info data

Based on the data from the above table EPC problems are associated with group 60-69. However, on Expert Systems Diagnostics Group 60, holds the EPC Adaptation data, group 61 holds EPC-system 1 data and group 62 holds the EPC system 2 data. Group 66 holds the speed-o-cruise data.

NB! If you found this information useful, please link to this page.

EPC DEMYSTIFIED CONTINUED 1

Continued from EPC DEMYSTIFIED.  

  ....But it’s not that simple. There is a lot more to it than meets the eye.....

 PART 2

But it’s not that simple. There is a lot more to it than meets the eye. Cars exclusively use embedded microcontrollers (µContollers) with embedded firmware in preference to microprocessors with loadable software. In order for a microprocessor to function properly in any device, it must contain dedicated internal circuitry and firmware specific to its function, have inputs and outputs and an oscillator circuit among other circuitry and an OS (Operating system). A DVR (Digital Video recorder), or a PVR (personal Video recorder) or a set-top-box or embedded network appliance or data router are just a few examples of such systems. µControllers  are less significant and less sophisticated than microprocessors, more dedicated to its specific need, often cheaper, faster, safer and smaller. Embedded µControllers are therefore the natural choice for car manufacturers. And there are several manufactures that produce µControllers families specifically for the motor trade.

So it should be understood that companies like Bosch, Digifant, Delco  and other engine management ECU manufacturers and electronic module manufacturers uses the same microcontroller chip families or similar microcontroller chip families, designed and manufactured for them by a selected few silicon chip manufacturers.  In the same vein, computer manufacturers like IBM, Dell, Sony, Toshiba and Lenovo, etc. all use microprocessors manufactured by Intel Corporation or AMD in their laptops and computers, whereas Apple uses microprocessors manufactured by Motorola.

Baring in mind, that much like Motorola, Intel Corporation and AMD produces different featured microprocessor chips with different instruction sets,  along with their auxiliary support chips for low-end and high-end computers; such as 4 bit, 8bit, 16bit, 8086 family of chips, 32bit Pentiums, I5, I7, 64bit, XEON, 128bit big Endian and small Endian microprocessors etc; so does Infineon, Altera, Freescale, Atmel and ARM etc, manufacture different featured microcontroller chips for both low-end cars and high-end cars which are specifically chosen for their internal features and software by the various ECU and electronic module manufacturers like  Bosch,  LUCAS, DENSO, Delco, DELPHI, FENIX, HITACHI, HELLA,  MARELLI, Siemens, etc. These microcontroller chip families can roughly be categorized into four sub sectors, those specific to Powertrain functions (P), those specific to the Body and Safety functions (B), those with specific functions for Chassis (C) and those specific to Internal Convenience & communication(U).

In a nutshell all the sub systems in your vehicle are controlled by these on-board computer chips, each at the heart of an electronic module flanked by associated components and sensors. Each of these modules are in fact a fully fledged computer in its own right, situated in various positions throughout the car and linked together by a wired networked called a network bus and all are accessible through the Databus diagnostic interface for adaptation.

When the ignition is switched on, several dashboard warning lamps light-up and stays lit for the duration of the internal test cycle (<30 seconds). Should all tests check OK, all lights goes however if all systems does not check out OK, the relevant light will stay on and a fault will be logged in memory . After the car is started, the ECU monitors all sensors  and continually takes readings from the complete range of powertrain modules and sensors. These readings are then compared with default readings stored in the operational logic of the  system. Should the sensor reading coincide and agree with the stored program value or values, the microcontroller will send the  required outputs to the relevant actuators, for example the injectors. If the sensor readings differ and are out of specification,   "not within the required limits",  it will take another and if this sensor reading continues to be ‘out of limits’ a DTC will be triggered and sent to non-volatile memory. Depending on the nature of the fault, the embedded program may or may not instruct the microcontroller to make internal changes, thus operate on different criteria until a repair is effected, or until the fault has been cleared.

So whenever a mechanical or electronic problem arises in either the Powertrain (P), the Body (B), the Chassis (C) or the internal Conveniences & Communication (U) areas, the relevant module or modules triggers the on-board self diagnostics program and generates a DTC (Diagnostic Trouble Code) which is then stored in the non-volatile memory of the ECU for later retrieval by mechanical technicians. At the point When a DTC code is logged in memory, the system self-diagnosis system also alerts the driver with a visible indication  of trouble by turning on a warning light on the dashboard like the "EPC light", or the "Malfunction Indicator Lamp" (MIL) which on European cars is known as the "Check Engine Light". This doesn't tell you  the nature of the problem, even though it could be something serious, or not. After the necessary repairs are completed, a diagnostic scan tool should be used to clear the DTC errors  and to turn the malfunction indicator light (MIL) or EPC light off. Thereafter the car should be taken on a short test dive to ascertain that the previous drive issue or issues are resolved. Then the car should be hooked up to the diagnostic scan tool once again in order  to confirms that the DTC or DTCs is also no longer present.

The nature of such mechanical problem may  prevent the engine from starting or it may idle erratically, switch off immediately after starting, refuse to rev higher than 1500 rpm and impede driveability (limp mode), difficult cold starting, misfire, lazy acceleration, high idling speed, fluctuating rev counter, excessive fuel consumption, difficult warm starting, excessive black smoke, poor engine response or emits blue/grey smoke,  etc ... Each of these faults and so many others each produce individualized codes.   In most cases it would be expedient to engage the services of a roll-back to get your car to a VW service center so that diagnostics can be run on the car.

With sufficient knowledge and an appropriate diagnostic apparatus (Autoboss, Pico Scope, Range, VCDS, AutoEnginuity,  ScanXLpro), code reader or scanner, plugged into the car's 16 pin diagnostic plug, mechanical minded persons can read these faults, print then or save them to an SD card or harddrive, send signals and communicate with the ECUs, read the measured values and interrogate the actuators. The DTC in memory however do not identify the part that has gone faulty but rather provides you  with a general idea to its area of origin. Often long before a DTC code is generated the fault may already have existed so when the you view the DTC it could show that the fault occurred twice of thrice or even six times before. The ECU software is designed to monitor the frequency of error and if it is an isolated occurrence the ECU clears the fault after a certain distance is traveled but that dependent on the severity of the fault. For arguement's sake lets say 300kms. If it happens once in 300kms it could automatically clears the fault but should it happen four times during the same distance a DTC will be registered, the car could go into limp mode since it may be unsafe to drive the car if it's a breaking or steering issue, or shut the engine off if the O2 sensor went faulty and can't regulate the smoke pollution, or disable starting if the knock sensor triggered the DTC as there may be no oil in sump which could amount to a very expensive engine repair. In the case of the latter, the oil light should have illuminated long before the knock sensor shuts the engine off. However I have encountered a problem with the wires that plug into the oil sensor that became brittle due to engine heat and  subsequently broke off. As a result the sender  sent the low oil condition but it never arrived at the the ECU hence did not turn-on the oil-low light. I only became aware of this when my EPC light went on due to the knock sensor. See picture in blog.   More ...

EPC DEMYSTIFIED

EPC DEMYSTIFIED IN THREE PARTS

PART 1

In a global village where defined lines between languages and nationalities, technologies and terminologies have become completely blurred, it is important to create terms of reference in discussions, so that we are all on the same page but pronunciation can at times offend the ear. To elaborate, some people say "tomarto" (tomato) some say "tomayto", some say micro computer and some say microprocessor, some say Electronic power control (EPC) some say Electronic Pedal control (EPC). But that's just semantics, the bottom line remains, that it establishes a common ground for people of different geographical spaces to discuss common topics.

In response to the hoards of queries I recently received and the abundance of confusion there is out there about EPC (Electronic Power Control); and in reply to the thousands of e-mails I received regarding EPC (Electronic Power Control) that I haven’t been able to reply to as yet nor will ever be able to, I decided to dedicate the next few episodes of my blog to explaining the EPC (Electronic Power Control) problem many VW drivers and VW owners are having with their cars as if they were two year olds. (Not that two year olds can relate the subject at hand).

I have explained EPC in previous blogs, namely EPC light revisited explained and EPC why-engine-light-comes-on, however, I am going to elaborate on the EPC (Electronic Power Control)  concept and demystify it for the benefit of all these people mentioned above and all those destined to encounter this problem at some time or the other. The question is not if you will encounter an EPC problem but rather when you going to encounter an EPC problem, its just a matter of time. Be that as it may, for the sake of simplicity, and by analogy, I'm going to compare the workings of the EPC (Electronic Power Control) in a car to that of a PC (personal Computer) which in my humble opinion will aid understanding.  So here goes....

Electronics as a whole has intrinsically influenced human life globally, especially since the advent of the silicon chip. Through the evolution of said silicon chip, Microprocessors have become so common place, that it finds itself in virtually every modern day technological advancement from computers to televisions, cell phones to cameras, medical equipment to the very cars we drive, to mention but a few. As a result virtually everyone out-there, has heard of, or are familiar with the terms microprocessor, microcomputer or just computer, and as such, it establishes a basis to discuss familiar concepts. Most people in the "Secular World" either owns a computer or uses computers and accordingly have some understanding of its hardware and its software, and how well these complement each other and seamlessly work together. I mentioned this purely in preparation to my assertion that  follows. However, all those non-technical and all-thumbs people and those  who say "you don't have to know how an engine works in order to drive a car", are totally excused.

EPC for Hands-on Dudes, Savvy Ladies and other pragmatic people.
Computers can roughly be subdivided into building blocks, each of which is responsible for a specific function or a collection of functions. As such a combination of these specific functions gives rise to the correct and proper functionality of the computer or computer based device. For instance, the computer hard drive functions as the storage unit that holds the operating system, application programs and user data. The DVD Rom, serial port, keyboard and mouse acts as input devices. Whereas and the speakers, printer & screen act as output devices, doubling-up as the interfaces of information interchange between man and machine (computer). The motherboard houses the CPU (central Processing Unit / Microprocessor chip) it ancillary / auxiliary timing chips, control and data buses, RAM and sub circuitry for  AGP, PCI, MR1, PCMCIA, USB, Ethernet, Fire wire, parallel connectivity, etc. When all these specific components play together nicely, we are guaranteed a fully functional computer and a happy computer user.

Likewise the car can be subdivided into building blocks each responsible for a specific function. In this instance, the engine is the source of propulsion which delivers it to the rest of the drive train. The instrument panel, the steering wheel, the transmission and the braking system constitute some of the input and output devices, also   doubling-up as the interfaces of information interchange between man and machine (car). The electrical system; the ECU (Motronic control unit), Control unit within the dash,  along with its auxiliary modules, oversees the overall timing, sensor, actuator, control and data bus, as well as block components like the Radio, air conditioner and central locking etc. Once again, when all these discrete components play nicely together, we have a perfectly functional car and a happy driver / owner. More...

DRIVE BY WIRE

VW - DRIVE BY WIRE (Drive-by-Wire)

If you arrived on the VW Polo website because you searched for  Drive by Wire (DBW), EPC, or EPC light or engine won't rev, Steer-by-Wire, or limp mode,  then you have certainly arrived at the right place. There are several definitions for ECP, the first of which will be explained, is Electronic Parts Catalog (EPC).

EPC stands for Electronic Parts Catalogue (EPC) and all Audi, Volkswagen,  Skoda and SEAT parts are listed in ETKA V7.2 EPC (Electronic Parts Catalogue). This catalogue is purchasable online and downloadable but the file is huge. Companies like Mercedes Benz, Toyota,  Enigma, Attrakt among many, many others host computer based electronic catalogs of the individual auto parts and accessories that make up their engines, cars, tractors, specialized machinery and farming equipment etc. Restated, an EPC is a catalogue in electronic format much like CVS data or a database file or similar, that can be downloaded or is accessible online.

Then there is the second type of EPC - Electronic Parts Catalog (EPC) software. MultiCat and Msys.EPC are companies that specialize in the software that can display an exploded view of an assembled device. For example, the exploded view of an engine, or gearbox, or cylinder head, showing the individual bolts and nuts, flanges, hoses and brackets, etc. and their component part numbers.

Thirdly, there is also the Electronics Parts Catalog (EPC) which is an electronic list or database of semiconductor components, from diodes to transistors to integrated circuits to thyristors, etc... This EPC is often called and equivalents book or catalog and hosts the specifications of semiconductors from several manufacturers. A typical EPC is the RS Electronic Components and Tools Database. This EPC doubles up as the third type of EPC which is the Electronic Product Code. Component Product Codes look like,  1N4148 or BC337, MCP2515, TYN812RG, etc... for electronic components.

However, there are many more EPC definitions, some of them can be found at the end of this blog. I could explain all of them individually but none has any relevance to the subject at hand, viz EPC - Drive by Wire. Drive-by-Wire also know as  DbW, Steer-by-Wire "x-by-wire" or simply "by-wire".

DRIVE BY WIRE

And finally, the Electronic Power Control (EPC) that freaks out almost each and every VW 1.6 Polo, Audi TT, Skoda, SEAT and  Golf TDI, owner. Most vehicles with Drive by Wire [Drive-by-Wire (throttle control)] usually have a Electronic Power Control (EPC) indicator lights on its dashboard which lights up when  there's a problem with the Drive-by-Wire system. This would involve the two accelerator pedal sensors G79 and G185 and in some cases the two sensors G187, G188 inside throttle control valve body - control actuator. [As discussed in my previous blogs] When the engine idles, neither the Throttle Valve Angle Sensor nor the Accelerator Pedal Position Sensor are monitored for faults by the ECU, as such, the engine does not respond to accelerator input but will limit engine to 1200 RPM.

The  basic components that constitute the Electronic Power Control (EPC) circuit. 

There is no throttle cable involved, because its an electronic throttle control.

The Electronic Power Control (EPC) circuitry consists of EPC light, Accelerator Pedal, Throttle Control Valve,  DBW  (no throttle cable,) Injectors and the Engine Control Unit (ECU). Have a look at the diagram above. The inputs to the ECU is marked green and the outputs from the ECU is marked blue.  Check that the brake light bulbs are OK, if not check the brake fuses. There are other inputs to the ECU from numerous other sensors or units for example the Automatic Gearbox Control unit, Cruise control unit, Air conditioning unit, Lambda Regulation unit, Knock Sensor units, Alternator, Engine Speed Sensor unit, ABS and the  Power-assisted steering unit to mention but  a few. 

The CAN-Bus bidirectional connection is marked in orange. Some of the other inputs like Knock sensors and Lambda regulator and Engine Speed Sensor unit can also cause the EPC light to come on. If the Engine Speed Sensor unit is responsible, it will reset itself after a while and if the Lambda regulation is faulty the vehicle will smoke and turn on both MIL and EPC lights, but if the Drive-by-Wire - DBW (not drive by cable) system is faulty then only the EPC light will be on.

Both the accelerator sensors and the throttle valve sensors work on the same principle since all 4 of them are potentiometers. The input voltage is 5 Volts and the increments are in millivolts implying that there is an  acceleration range of between 0 and 5000.  Throttle valve angle  sensor 1 and Throttle valve angle sensor 2, Accelerator position sensor 1 and Accelerator position sensor 2 sliders makes contact with the resistive track and outputs the appropriate voltage level to the ECU. These resistive tracks are prone to go faulty since they are gold plated contacts running on gold plated copper tracks etched on a PCB. Over time the contacts wears right through the gold and copper plating, only making contact with the bakelite or fibreglass substrate. This type of potentiometers are less reliable than ceramic thick-film potentiometers.

When the EPC warning light goes on and your acceleration goes limp and the engine won't rev-up there is an easy cure but there may be exceptions. Get the car home even if it means driving really slowly in "Limp Mode". Once home, disconnect the battery for about 15 minutes or so, but not more than 20 minutes then reconnect. NB! do not disconnect the Live terminal, disconnect the Earth terminal. If the battery is disconnected for more than 20 mins you will lose your radio settings since the radio also participates in volatile and non-volatile memory of  the CAN-Bus. 

Reconnect the battery but make certain that the ignition is off. Once this is done, turn on the ignition so that the dashboard lights go on but do not start your car and DO NOT touch your accelerator pedal. After about 5 minutes the throttle body will aligns itself. After 10 minutes turn off the ignition, wait for 2 mins then start the car and let it idle for abut 2 minutes as well. By now, the EPC warning light should be off and the engine will rev as normal.You may have to to this twice. If this worked for you, please do give me some feedback with a comment.

VW Airbag diagnostics 

VW Instruments - Immobilizer

   

DON'T FORGET to VISIT

THE PREMIER 

SECURITY EXPO IN
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COME MORE EPC DEFINITIONS

EPC - Engineering, Procurement & Contracting, 

EPC - Engineering, Plant  Construction,

EPC - European Paralympic Committee,

EPC - Electronic Product Code, 

EPC - Event Promotional Council,

EPC - Energy Performance Certificate,

EPC - Engineering, Procurement and Construction, 

EPC - Event-driven Process Chain, 

EPC - Evolved Packet Core,

EPC - European Patent Convention,

EPC - Eastern Provincial Council, 

EPC - Electronic Poetry Center, 

EPC - European Policy Centre,

EPC - European Political Community, 

EPC - European Political Cooperation, 

EPC - Evangelical Presbyterian Church 

EPC - Export Promotion Council, 

EPC - Electricity Plant Controller, 

EPC - ElectroPlating Cathode,

EPC - European Payments Council,

EPC - Electronic Packet Collision,

EPC - Electrical Professionals Council,

Etc...,