Oh5TTquattro

I have no idea where to start, but my left side marker lights on both the front and back are not working and the gauge lights that light up the gauge faces are also inoperable. The dimmer still works, and the needles are lit up. I have no power to the fuse for the left marker lights. If I can't figure out somethign this simple by myself maybe i'm better off selling this car. Lights are easy to figure out but the wiring diagrams are chinese to me and i'm at a complete loss. I guess now would be as good a time as any to learn how to read them. I just don't want to screw this up this is the nicest car i've ever owned, it's in great shape, but this is a real eye opener as to what I got myself involved in.


I did find a corroded ground under the battery for the coolant after run pump, but it wasn't even cutting off the connection yet. The car is a california car so corrosion isn't as bad as if it's spent its whole life up North.

Thank you in advance.

Mister Bally

Start with a VCDS scan to see if it detects a problem in the headlight switch. Otherwise standard automotive electrical troubleshooting techniques apply.

Best to take a class at a junior college or look a a book at a library since you mentioned that wiring diagrams are Chinese to you. You will need a multimeter to properly do the job.

Oh5TTquattro

I'm going to have to purchase one. Should I purchase the ross tech VCDS? I've read about limited functionality with the cheaper copies. I actually had to replace the DLC connector and crimp on one new terminal for the 12v+. I'd like to know if there's an upgraded dlc connector with a secondary retainer or lock. This connector doesn't seem great the terminal pushed out and broke the retainer, but it could've been the pin size on the pos chinese connector my laptop has.

I have a laptop with this Delphi program that is a capable scan tool but apparently it is limited with Audi. I did retreive a 01305 code for the instrument panel stating
-databus for infotainment
-faulty
-intermittent

as well as a 01304 code for -Radio -No communication -Intermittent.

The only thing under the headlight section that this program can scan for is headlight aiming motors or something like that. I will try a key on engine running test to see if it picks up anything else. It has an intelligent system scan feature where it scans all systems and returns any codes.

This car has 98k and it was extremely well maintained and stored indoors. I've worked on the car more than i've driven it so far trying to get all the maintenance done and this just happened. Thank You

Oh5TTquattro

I've honestly only learned how to read mostly american and some foreign diagrams. I have a thorough understanding of electrical systems but this car is more involved than anything i've owned or repaired. I've dealt with some wiring nightmares in my life and never paid to have a car fixed. I just need to calm down and learn how to read these diagrams they are different.

I'm just over it i've done a sickening amount of maintenance that cost way more than anticipated and this just happened when I went to pull the car out.

I guess the biggest thing that worries me about this car is programming/coding modules and various sensors. Can it all be done with the VCDS? Can every single electrical component and system on this car be coded or programmed with it?

I have three multimeters, a loadpro and a power probe IV. You should look into a loadpro and the science behind it, i've used it and it works.

Mister Bally

Although for the D3 A8's, this thread applies to the TT MK1's regarding diagnostics and manuals and more....

https://www.audiworld.com/forums/a8-...-read-2877219/

Oh5TTquattro

Thank you. Once I calmed down I was able to read the diagrams. I have diagrams the size of building plans for my other vehicle that I found by chance on ebay and it's a pleasure to work with them compared to the tiny pics in the bentley service manual. I'm going to order the rosstech VCDS. I found a thread that described the same exact problem but affecting the right side, there was however no info on how or if he got it fixed. I'm hoping it's just the switch. I'd bet money on it that it's the switch.

I found a switch for an a6 that looked identical except for the face plate for a much better price but i'm just going to buy the correct one for my vehicle rather than chance it. So can I code, and program every module with that VCDS?

Do you think it would be a waste of money to get the actual Audi VAS5052. If I factor into the cost of another laptop I might consider just spending five hundred on it. Then if I ever wanted I could get additional diagnostic cables if I was in a real jam. I have a breakout box for my other vehicle with various harness adapters of all sorts.
I was curious and searched to see if they made a breakout box to hook into the ECM harness, but they don't. I have a breakout box with an abs and ignition system adapter/harness for one of my vehicles and it was worth every penny.

edit: I'm sure i'll regret it but I bought a VAS 5052 off ebay that was slightly used for $500 shipped. I would've spent 150 to 200 on a laptop plus the rosstech vcds so I think it was a good choice.

Oh5TTquattro

It was the headlight switch. I don't know what block to look under in vcds. I now have elsawin and the wiring diagrams are way better to navigate than using the bentley manual.