SLVVR6

This might not be the right place to post this, but thought I would try. I have a 2002 Passat 1.8t (I know, it isn't an Audi, but thought I would ask anyway). I bought the car with noise in the engine when running. I ran it the day they unloaded and made a grinding sound in the engine bay. A day or so later I thought I would scan the ECU and see what was going on. I couldn't communicate with the ECU. I figured I would determine why I couldn't once I had repaired the engine. Got the work done on the engine and went to start it. Wont start, no CEL in the instrument cluster. No power at fuse 29 or 32. My understanding is that if you don't see a CEL in the instrument cluster, the cluster isn't communicating with the ECU and most likely is an issue with the ECU. I found the ECU (ECM) power supply relay (J271) and have been playing with it. THere are four wires coming out the back of it. Two red wires have 12v constant. I wire is white/black and connects to the ECU. I assume this is the ground for the relay. The other wire supplies voltage to fuse 29 (wire is red/grey). The more I played with that connection, the more confused I got. I had the chance to look at a running car (same year/engine) and here is the comparison.

Running Car: Non Running Car:
Key Off Relay In Relay In
Red (Big) 12.29v 12.58v
Red (Small) 12.29v 12.58v
White/Black 12.35v 12.55v
Red/Grey 0v 0v

Key Off Relay Out Relay Out
Red (Big) 12.40v 12.54v
Red (Small) 12.40v 12.54v
White/Black 2.59v 2.58v
Red/Grey 0v 0v

Key On Relay In Relay In
Red (Big) 11.70v 12.23v
Red (Small) 11.70v 12.23v
White/Black 0.79v 12.23v
Red/Grey 11.87v 0v

Key Off Relay Out Relay Out
Red (Big) 11.70v 12.54v
Red (Small) 11.70v 12.54v
White/Black 0.42v 2.85v
Red/Grey 1.94v 0v

Now, here are my questions:

1. Could a bad ECU cause this issue?
2. Would a bad cluster cause me not to be able to communicate with the ecu?
3. Are ECU's testable?
4. Any other ideas?

SLVVR6

Lost my formating on the table. Here is the table:

VoltageTest.jpg?t=1254096139

e36graduate

can you try putting in a new or swap out the relay?

SLVVR6

I had another ECM power supply relay and it made no difference. I find it hard to believe that I have two bad power supply relays. I actually tested the relay by applying power to the coil and it would click, checked continuity and it seemed to work.

SLVVR6

Does anyone know if it is possible for the dealership to test ECU's?

SLVVR6

Any help???

hali410-Brunei

seems like this relay is commonly failing...
I also have the similar problem hence the B7 won't engine won't start. Here is the fault code ;

2 Faults Found:
17925 - Power Supply Relay for ECU (J271 or J363): Electrical Malfunction
P1517 - 008 - Implausible Signal - Intermittent

you manage to find the relay, you have a picture where the relay is located?
and what's the cost of it?

CrookedToad

so ya five years later i know... Where the hell is this relay. i have looked in the ecu box under the ecu under the steering column and i cannot find this relay. is it another number than #30? What is J363?