Giovanni Giovino 6.0+6.0TT

Hello,
Just so we are on the same page, is the relay you replaced located in slot #3 located right below the orange 40AMP compressor fuse, as shown in pictures in post #52 in the attached thread link, upper relay with # 370 on it.


https://www.audiworld.com/forums/a8-...2905353/page6/


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MP4.2+6.0

Hi--not really in line w/ this thread exactly, but on D3 W12 I came across a relay that seemed crucial to the whole car/motor functioning. It was in the sealed black plastic box in the plenum area directly under one of the twinned ECU's that is mounted on top of the same box. Next the HVAC unit and filter. I opened it and found basically one single pretty normal Audi relay in this big space, almost like it was sealed in Fort Knox or something. In basic testing, without that relay motor seemed dead IIRC. Any sense of what that is, if 4.2 has one, if it has similar box, etc.? Since mine was working I had no reason to try to diagnose or look at wiring diagram further to try to figure out what it did.

Giovanni Giovino 6.0+6.0TT

Hello MP,
Me neither.... but you know I have to look now.......

Giovanni Giovino 6.0+6.0TT

Astro,
You never did tell us if the brake lights work after you replaced the BL switch, so please let us know, ALSO, any chance of posting some pictures of the dash when you insert and turn on key ?

MP4.2+6.0

Yep, kind of why I had to open it too... After you do, ask yourself why they didn't redo it a bit and put the ECU's inside there instead of just thrown in the plenum with a few chastity belt brackets.

Shark_V8

In 30 years it's been rare to actually encounter a relay fail. I can think only a couple of times in older cars, heavy duty or high current switching.

A quick scan of the car diagnostics from the entry & start auth module will yield the issue. Other than that you have to trace voltage through the relay base terminals (in-series chain) during an attempt to starrt (=PITA)

Shamoye Lewis

sounds like he might have a neutral/park safety issue, see if the P R N D S is all lit up, if it is Neutral safety issue car will never start, if it not still try this remove the ash tray in the front of the shifter there a small hole take a screw driver and push it in the hole push it down you should be able to move the shifter out of park put it in the N position and try to start... if that doesn't work Ill tell you how the try to activate the starter manually to test it, it might just be dead also...

Matt94

Im guessing once vcds is hooked up you'll find the starter is jammed and you may need a new one. Also I have an 04 and I don't need to press the brake to start the car.

Mister Bally

Just a bit of related humor. My son's TT dash tells him to press the clutch to start, in Fatherland tongue....

Shamoye Lewis

because the TT is manual transmission, there's no A8 in manual