I searched the forums but did not find anything applicable.

I have a 2009 TT with 18K miles. Garaged and driven regularly. About 3 months ago the car started having the check engine light go on and off. It never blinked. After replacing relays, fuses and the DME, the dealer determined it was the wiring harness. Wiring Harness replaced under warranty.

2 months later, after no other issues, the following things are happening, but not regularly:

1) The backlights to the speedo/tach etc are dimming and not coming on sometimes (happened 2x)
2) The parking lights will stay on after I turn the car off, and wont go off no matter what I do with the handle.

The dealer took the car in and says that they can't find anything and they checked the contacts in the light switch.

Can the harness be connected improperly here? Is there any other likely issues? I really love this car and as the last of Mezger manuals is something I was planning on modding and keeping...but this is really putting me off of it.

Oh, its a CPO car under warranty, so this is costing me nothing but heartache...

Thanks in advance.

 

Typical response to a question like this is "how's your battery" - amazing how many problems a weak or failing battery can cause. When you say parking lights stay on after the car is off - is it both parking lights or just one side? Do you get a message in the OBC that the parking lights are on? It may be that you inadvertently left the turn signal lever down - that will leave one side of the parking lights on.

 

Ok, the turn signal is a new one to me. I will check that next time! In my other cars that does not matter. Battery "seems" fine, no indication its the battery, but how would I know?

 

How old is it? I had a 3 year old battery that was on a maintainer, always started just fine. One day start, next day no start. It's a weak link in P-cars. I'm sure dealer or Autozone or someone can check the battery. If it's the original battery, it may be on its way out.

 

its the original battery. I will get it checked.

 

Have the alternator checked also (hopefully the guy is competent that runs the tests on the alternator). I had similar type problems and even though the battery was mostly fine, the alternator wasn't and funky things would happen as the alternator had intermittent issues, so when it charged the battery I had no issues, but when the battery ran low, I had a bunch of issues.

Since the alternator issue was intermittent, it took a little bit of convincing for the service department to trace the issue to the it.

The other thing I would check is the ground of the harness to the ground of the battery to make sure that the harness ground is truly grounded.

Good luck and let us know what it turns out to be.

 

Well, user error is often the most likely culprit...at least it was with the parking lights issue. YES, if you leave the turn signal lever in other than the detente position it will leave the parking lights on. My other german cars, including my 928 never did that, and I apparently never left it in other than the detente position for the first year I owned the car. THANK YOU.

I will figure out what is making the dash light go dim next and I'll update the board if its either a battery or an alternator issue.

This board is so much easier than dealer service...