Hello all.


First I am new to here and not really an "Audi expert" I do the normal maintenance on an A4 (2004), Q5 (2018) and Q3 (2023). No work on the Q3 as the first oil change is not due yet.


The A4 as started out with a simple problem but others has showed up without anything being done to it. I have attached the scan report out of my scanner. I am pretty sure a lot of the codes are due to low voltage on the battery.


1. First problem - After we got the Q3, this car was not driven as it would have been normally and the first problem was a dead battery. The battery was a few years old, still under warranty so it was replaced under warranty. Installed new battery and several weeks the battery was dead again...moving on to problem number two...

2. The driver door window stopped working, then followed by the power locks, trunk and the rest of the windows stopped working. Charged the battery and 3 days later it was dead again. Dead as in 0.00V.

3. After this happened, I tried to scan the car and my scanner (Matco) normally recognizes the VIN but this time I had to manually enter the VIN before I could complete the scan (see attached report)

4. Did some basic troubleshooting and reading the forums and determined that the comfort module was most likely the drain on the battery. With the windows, locks, etc not working I purchased a used module with a 90 day warranty. Installed and still have the same problems. I have not left the battery hooked up as I dont want to damage the battery with a deep discharge.

4a. Comfort module had the exact part number with matching letters at the end.


My questions are:


A. Where does the comfort module get its power from? I have two fuses on the left side of the dash, but they are good and I have power on both sides of the fuses.

B. Is there a relay that controls the comfort module?

C. Any other fuse blocks on the car? I found two at the ECU, the normal ones on the left side of the dash and what looks like 3 fuses on another module underneath the kick panel.

D. Anyone have a copy of the block electrical diagram or a wiring schematic? I would like to see a black diagram if possible to help me understand the order of operations of the electronics.


Any suggestions or ideals would be greatly appreciated.

 

wow, that's a lot of problems at once! I'm not an expert, but it sounds like there might be a bigger electrical issue at play. Have you tried disconnecting the battery for a while to see if it resets anything?

 

That is what I am thinking. A master fuse or relay somewhere that has blown. Hoping someone on here might have some guidance for a wiring schematic or block wiring diagram