T5 Electrical Problems: Troubleshooting & Repair

Hello.

I'm having the following problem with my T5, manufactured in 2005, engine code AXD, power output 96 kW:

When I turn on the ignition, the ASR (Anti-Slip Regulation) light sometimes comes on and the engine doesn't start. If I leave the ignition on, the radiator fan starts running after about ten seconds. After several attempts to turn the ignition on and off, the light goes out, the engine starts, and then runs for hundreds of kilometers without any problems. The error code in the diagnostic memory is "01314 Engine Control Unit - No signal/communication intermittently." I've already replaced relay number 109 as a precaution and checked all the ground connections, but the problem persists.


Okay, before I forget, the problem first appeared after the alternator was replaced by a Volkswagen mechanic. Coincidence?

Sure, here is the translation of the text from German to English:

"Hello."
Michael.

Hi,

I suspect that either the engine control unit (ECU) is having problems or there's a loose connection in the wiring or connectors leading to the ECU.

Best regards, Rainer.

Hello everyone!

Rainer K. wrote:

...the wiring/connectors to the engine control unit might be loose or faulty...

A temporary contact problem is indicated by the radiator fan running at its highest speed. This happens when the external temperature sensor (located behind the license plate on the bumper) is disconnected and the ignition is turned on simultaneously.
However, in that case, an error would also need to be stored in memory.

Have you checked the AI module (address 17) to see if there are any error codes stored? And also the brake control module (address 03)?

Best regards from Munich!

It seems that the issue with the radiator fan is likely a normal occurrence when the fan control unit doesn't receive a signal from the engine control unit. The error message mentioned earlier originates from the ASR Front MK25 control unit, while "Msg" itself does not have any error messages.
Today, I disconnected the auxiliary battery under the driver's seat (which definitely wasn't done during the alternator repair) in an attempt to reset all the control units, but unfortunately, it didn't work. The problem has been occurring for about 4 weeks now, and I've driven approximately 5000 km with the bus during that time. There have never been any jolts or other interruptions during the drive. The error usually appears after the car has been parked overnight, or after a long journey followed by a restart; it happens very rarely.

Hello!

I don't know how the cooler fan control system behaves in case of a communication failure.
As far as I know, the external temperature sensor is only processed by the combination instrument.

Okay, if you're experiencing issues with the engine management system, error messages related to it should also be recorded in the control unit (ECU), CAN gateway, (automatic transmission, if equipped?), etc.
Denke, daß Du auch schon bei allen anderen verbauten StGe die Fehlerspeicher gecheckt hast und diese leer sind/waren. Sure!
Consequently, the MK25 remains as a potential cause of the error, or there may be an intermittent break in the wiring.

Da vermutlich daran beim LiMa-Tausch rumgesteckt und -gezerrt wurde, täte ich Dir einfach gefühlsmäßig mal empfehlen, alle Steckverbindungen hier auf evtl. Wassereintritt z. B. to be checked.

Current idea: Try immediately addressing the installed control units in case of a fault. If the ABS/EDS/ASR system does not respond (anymore), start troubleshooting .

Best regards from Munich!

The following errors were fixed: the MSG was broken .

Hello!

Thank you for the feedback!

For informational purposes: What was the part number of the engine control unit (ECU) that you had installed?

Best regards from Munich!

The part number is 070 906 016 AJ. Unfortunately, I couldn't find any company that could repair it because it was too new, so I had to buy it directly from Volkswagen.

"Did you modify anything on the ECU (Engine Control Unit), such as tuning it via the BDM interface, which would allow access to the control unit's software?"

Because normally, EDC16 units are quite reliable.

Best regards, Rainer.

No, absolutely nothing to do with tuning. However, I should also mention that the car now has over 500,000 kilometers on it.

Transporterfan wrote:

no, absolutely nothing to do with tuning, although I have to add that the car now has 500,000 kilometers on it.

Okay, this is an argument .