So you wanted to own an Audi…

Chris Diagnostician New York Posted   Latest   Edited  
Case Study
Opus IVS
Trained By Techs
2002 Audi A4 1.8L (C AMB) (01J)
Crank / No Start

My step son has wanted an Audi ever since he totaled my A6

He saved up his money and bought a really nice 2002 A4. It sat in my driveway for 2 years before he was able to find a job and afford to put it on the road. I explained to him that sitting is the WORST thing that can happen to a car. We (me) have been chasing gremlins upon gremlins on our journey to get this thing road legal. 

This is one of what I am sure are to be many case studies from all of our (my) struggles...

I went out this morning to install a cooling fan control module to confirm the diagnosis from another case study, and found the car would not start, I did a quick check of the fuses, and found nothing blown. I had plans today and was not looking forward to have my fat ass diagnose this car on my ONLY day off, but what the hell...

I hooked up my scan tool, and saw that I had a code for open circuit on the ecm main relay. (the other code was made by me during the diag)

A quick look on service info showed the main relay was inside the E-box in the cowl...Fun

With the cover off, you can see the ecm, and to the left, buried, is the fuse carrier that holds the main relay. 

With the ecm removed, we are staring at the tcm.

This can be a pain to remove. Just unhook the circled clips and lift straight off.

Oh jeebus... 

That looks like some serious rust residue.

I want to get to the back of that relay. Just remove the circled clips, and the holder comes right up.

Great Scott!!

I don't Like the looks of this...

According to the diagram, pins 5 and 8 should send power when the relay is activated (key on)

With my high amp test light,

I can see that one leg is powered.

However, the other isn't.

Time to pull the relay.

Here is a closer look of the relay socket.

I took the relay apart and it was STILL burning hot. This thing was TOAST!!

Upon further inspection, I did notice the rear corner of the e-box was broken from a previous repair. I will address this when the replacement relay arrives. I will also clean or replace all contacts in the socket.

Thanks for reading.

(Wiring diagram courtesy of Motologic)

Here is a link to my tip/case study on test lights. 

+7
Hans Diagnostician
Utah
Hans Default
 

These cars paid for all my tools :D

+4
Default Ð Awarded
Nelson Manager
California
Nelson Default
 

That ECM looks a lot easier to remove than my 2006 Volkswagen Jetta TDI. That was fun. (Extreme sarcasm.)

0
Default Ð Awarded