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

   

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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...,

ENGINE TROUBLE, CAR PROBLEMS

VOLKSWAGEN, POLO CLASSIC CAR PROBLEMS

This blog is about my 2007 VW Polo Classic 2.0L Highline and other VAG cars in general. I have always been fond of good, solid, precision German engineering and I stand firm in my conviction that my VW Polo facelift  fits the bill. It therefore makes me wonder what happened in the manufacturing process? I often ask myself, - Was my VW Polo manufactured on a Monday that I'm having so much car problems and have to visit auto repair so often?

With the amount of issues I've had with my VW Polo, it rather looks like it was manufactured on a public holiday. It makes no sense why I am having so much car problems with it. I have had a Mercedez Benz which was German engineered, I loved it. I also had an Opel Kadett GSI 1.8 with digital dashboard that was German engineered, I simply adored it.  I had three company cars all of which were German engineered VW Passats.  I've also owned two VW Golfs, both of which were German engineered. The first VW Golf was a 1100 Golf-1, the second was a 1600 VW Golf -2 CLI with large bumpers. All of which hardly needed  automotive repair. My VW Polo 2.0L Highline 2007 model is however is very different from all the VAG cars I have owned before.  For example, the electromechanical system of the VW Polo ascribes to the OBD-II standard as well as CAN-Bus and its certainly not the easiest VAG car to repair.

This Volkswagen  Polo has an on-board computer which interfaces with an ABS module, the Interior Electronics Module, the Engine Control Module, the  Immobilizer Control Module among so many, many other electronic modules. Ostensibly it could be said that each of these modules, is a computer in its own right and they are all daisy-chained on the same OBD2 / OBD II or CAN Bus network.

Auto repair :-

The above 16 Pin DIN J1962 socket is provided  for a diagnostic tester to interface with these Electronic Modules, and is the only way to communicate with the car. This socket is situated in various places on different models and makes of cars. For instance BMW's normally have them under bonnet in the engine compartment. Most Volkswagen's have this socket under the dashboard on the driver's side. Some cars have it in the glove compartment, some have it in and around the ashtray.

My VW Polo had an idling problem, it was idling around 1200 rpm which progressively increased and hovered about 2000 rpm. There is no adjustment because there is no accelerator cable / throttle cable - it has Drive-by-wire (DMW) also known as Electronic Throttle Control (ETC). It  is the latest automobile technology that replaces the conventional cable linkage system between the vehicle's accelerator pedal and the engine throttle body.

Anyway, the high rev drove me crazy, especially when changing gears, the revs just wouldn't come down or took forever to do so. After two days, the EPC light came on and I took my car  off to the agents who reset the throttle-body valve. It was fine for just two days until the the rev counter started hunting between 800 rpm and 1200 rpm and the EPC light came on again. I took the car back to the agents, only to be told that the throttle body was effectively faulty. The cost was equivalent to one monthly car installment and that excluded their labour charge. So I decided to get a second opinion  before I forked out so much money, since I don't have a motor plan.

My new auto mechanic plugged in his Auto Boss Automotive Scanner and a few minutes later he said its the accelerator pedal that was faulty or rather the sensors that control acceleration which is part of the accelerator pedal. I asked about the possibility of the accelerator throttle-body being faulty and he says "no ways,  who even thought that? Your car revs higher than 1200 RPM". He the asked "does your EPC light come on?" and I said "yes". He then leaned into the car, grabbed hold the accelerator pedal with his hand and pulled the accelerator pedal upward. Immediately the idling seemed right, or at least to me it sounded right because it was idling at 950 RPM. By demonstrating this, even the data that was missing from one of the cells on the diagnostic tester's display came back and flashed the word NORMAL. He then released the pedal, the revs once again increased and the data cell  on the diagnostic tester's display went blank once again. After replacing the accelerator pedal with the Drive-by-Wire potentiometer (G79 & G185 sensors) attached, the idling was perfect and the EPC light stayed off.

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