I have a couple questions about my 2001 Audi TT Quattro..

First one is my headlight on passenger side died... I can turn on the headlights, the headlight will come on, off, on, stay off.. for a split second.. I tried testing the plug with a multimeter and I get no power. So my question is does the TT have some kind of computer on the headlights or transformer? Does it shut off power to the headlight if it doesn't get any power being drawn? I haven't tried changing the bulb, as I think it is something else causing the problem as the headlight comes on, off, on, stays off..

Next question.. My Quattro does not work.. my car is stuck in FWD, the rear wheels do not turn at all whether I have traction control on or off... a while back my car used to die out in the summer time for no reason, like if I started boosting to pass someone then let off throttle the car acted like it was turned off, but tracton control light would appear on dash and car would idle at around 800 rpm's but no matter how far you press the gas the car would stay at 800 rpm's (idle).. I would have to shut the key off and turn car back on and everything worked fine again.. I'm guessing this has something to do with the Quattro as it was slowly going out? I don't know if the Quattro ever worked since I bought the car, this was first winter I used it and first snow I found rear wheels would not spin.. I checked fuse, and scanned OBD, not sure if anything quattro related would show on a OBD scan or not, but only thing I get on OBD scan is my 2nd O2 sensor (guessing from having a borla exhaust installed).. I was told about the Haldex fluid and filter need changed every 20,000 miles.. since I've bought this car I've probably put 20K miles on it.. so could that make the rear wheels not spin if the fluid is low ?

Also I can not find a Haynes or Chilton's manual for the 2001 Audi TT Quattro are their any other repair manuals out there that are worth buying for this car?

Thanks..

 

I feel your pain. I have a similar problem. I've changed the filter and fluid. No Codes or anything regarding the Quattro. New Break light switch and still no luck.

I would say you have to replace your Haldex control unit tottaly. Looking at more than 900$ for a new one. Other than that, replace the oil, check the controller and pray it fixes itself

 

headlight issue... its possibly the ballast, not the bulb...

AWD issue... been there. if I got the car on ice, the rear tires would turn, but only because there was ZERO torque being transferred. As soon as I got into a situation with some traction, they wouldn't power out of anything. It wasn't the controller, it was the haldex unit itself (called the Haldex LSC, or limited slip coupling).
Replaced it for $500, and came with a controller. Check Vortex. The LSC works as a wet clutch. If the clutch material gets worn, it just slips. The controller will usually throw a code if its bad, but there won't be a code if the LSC is slipping.

Easy swap, but you need to track down a big triple-square driver. I think its a 16mm. Bought mine from snap-on. You'll need smaller triple square drivers as well, but 12 or 14 are the biggest I could find locally.

 

Thanks for the info, is there a way to check the ballast on the headlight with a multimeter to tell if it's bad? I've never dealt wth a ballast before.. I'm guessing it will put out some kind of voltage, but I don't think it will still be 12VDC, I'm guessing it should be higher and probably on the AC side instead of DC? Does the ballast go into a safe mode and quit outputting voltage if there is no current draw?

Also new finding on the AWD problem.. I had to have my car towed off of the high way the other day because I got stuck in the snow.. The tow truck driver said my rear wheels should have locked up when he was trying to tow it.. Said every Audi with quattro he has ever towed would lock the rear wheels after moving like 12 inches.. my rear wheels never locked up.. he towed it with front wheels on the lift and rear wheels on the ground.. he doesn't know much about Audi's but he was saying that someone may have taken the driveshaft out that connects the rear wheels to the front wheels.. so I'm thinking that someone may have taken it out.. (as the previous owner of the car did have it dyno tuned, and there are not a lot of AWD dyno shops around here).... or it is the haldex Limited Slip Coupling you are talking about that is slipping.. because if front wheels are locked to the lift and cant move the rears shouldn't move either if they were connected..

I guess I'll have to put it up on a lift and see if rear wheels even move with absolutely no traction like you were saying..

 

Well last night while changing my oil I figured I'd hop in the car and throw it in 1st, reverse, traction control on, traction control off, see if I can get the rear wheels to turn with 0 traction to them.. They didn't turn.. drive shaft is there and turns though.. so I'm guessing the LSC you talked about.. someone on another forum said that OBD scan will not show Haldex codes? Said I need to scan with VAG Com..

Well I guess I will start looking for a new LSC and see what I can come up with.. Thanks for all the help and information!

 

Most people who use FWD dynos will pull a fuse which controls the AWD, hence leaving it FWD. check your fuses....