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...

EPC LIGHT - REVISITED

VW POLO EPC LIGHT 

Most VW Polo, Golf, Audi, Passat and  Skoda  vehicles and probably every other VAG cars appears to have problems lately. In one sentence, the most common of these problems seems to be on obd diagnostics the culprit being the  wiring that interconnect all the electronic modules, aka the OBD II / CANbus. Virtually every car diagnostic test done on several different VAG cars produced the same faults. This implies that they are common, since they are recurring on different owners cars.  I can relate to this from my Television engineering days, when several same-make and same-model televisions all appeared to give the same problems. These VAG cars all seemed to have Intermittent / Implausible messages on the Data Bus and its highly unlikely that it could be the electronic modules themselves that are intermittent. Should this be the case, each and every one of these VAG cars then needs to be recalled because it looks like a defective design or assembly line problem.  But that's  wishfully thinking on my part which will obviously be met with and answer like - highly unlikely.

Wiring harnesses and cable assemblies for electrical buses interconnecting several MOSFET fast switching electronic modules each having an edge connector / plug whether it is gold plated or not, has parasitic capacitance. Add this  to the edge connector resistance and crimped wire contacts inside the plugs makes for interesting intermittent connections. The following list are faults /errors  that showed up on diagnostic tests on cars with EPC light problems, which  gives you some idea what I'm referring to. I've  abbreviated "Powertrain Data Bus" to PDB: in order to stop each fault from running onto two lines. Excessive comms errors and internal control module memory error intermittent are common faults caused by wiring harnesses.

SCAN TOOL ERROR CODES

1) 01312 - Powertrain Data Bus:  - Faulty

2) 18034 - PDB: error P1626 Missing Message from TCU  (Transmission Control Unit)
3) 18043 - PDB: error  P1635 Missing Message from A/C Controller
4) 18044 - PDB: error  P1636 Missing Message from Airbag Controller
5) 18058 - PDB: error  P1650 Missing Message from Instrument Cluster
6) 18270 - PDB: error  P1862 Missing Message from Instrument Cluster 

7) 18055 - PDB: error  P1647 Check Coding of ECUs
8) 18056 - PDB: error  P1648 Failure
9) 18045 - PDB: error  P1637 Missing Message from Electric Load Controller
A) 18097 - PDB: error  P1689 Implausible Message from Elect. Load Controller

B) 18104 - PDB: error  P1696 Implausible Message from Steering Column Controller
C) 18107 - PDB: error  P1699 Missing Message from Steering Wheel Electronics

D) 18057 - PDB: error  P1649 Missing Message from ABS Controller
E) 18259 - PDB: error  P1851 Missing Message from ABS Controller
F) 18090 - PDB: error  P1682 Implausible Message from ABS Controller
G) 18261 - PDB: error  P1853 Implausible Message from ABS Controller

Implausible signal means that it is "intermittent", even intermittent at the time the diagnostic tester was interfacing with the ECU's, TCU's, STC's ABS's, A/C etc... "Missing Message" implies absolutely no contact (Open Circuit) with the respective modules at the time of testing. Since VAG cars became inundated with electronic modules, our individual cars each have a few hundred more electrical connections than the previous generation of cars each and everyone of them subject to the tresses and strains of  the bumps on uneven roads and spirited driving. Add engine heat, steam, dampness and other weather conditions to this equation and suddenly these connections become tarnished over time. Tarnished connections are certainly not electrically sound and one way to clean these contacts is with contact spray but graphite or a grey ink rubber would be more effective to clean the tarnish off the gold plated PCB edge connectors. The Bentely VW manual suggest replacement of the whole wiring harness if  any problems arise but it comes at a cost of  $798.00 and that's for a 2007 VW Polo highline. I would hate to know what it would cost for a 2013 Volkswagen Touareg or 2013 Volkswagen Amrok not to mention 2013 Audi A8 or Audi TT .

VAG cars are really nippy and a joy to drive and I'm certain the bulk of VAG car owners enjoy spirited driving but many many VAG car driver probably regret this since they only experienced  EPC light troubles after they did some real spirited driving. I know this is absolutely true for Audi TT drivers who complained that their cars were fin until they gave it a nice workout. It is obvious centrifugal force, torque, tension, flexing, wind resistance and inertia plays their respective roles on the plugs and connectors. The EPC Light problems above, D through G appears to dictate that the ABS Controller is faulty or its edge connector / plug is faulty or the harness is faulty. B through C suggest that the Steering Wheel Controller is faulty or its edge connector / plug is faulty or the harness is faulty is causing the EPC light  to light up. Numbers 5&6 seems to favour the Instrument Cluster as faulty or its edge connector / plug is faulty or the harness is faulty which causes the EPC light to light up. Number 9 and letter A seems to blame the Electric Load Controller for triggering the EPC light. Numbers 1-4 and 7&8 seems to suggest some other electronic module caused the EPC light to light up. All these modules have one thing in common, they are all associated with the Powertrain Data Bus. In essence any module associated with the Powertrain Data Bus can cause the EPC light on VW Polo or other VAG cars to trigger.

THE SECRET TO MAKING MONEY ONLINE.

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

More on EPC light DEMYSTIFIED....