Multiple electrical issues.

I"m new to this forum and new to VWs, so please keep that in mind when making suggestions!


I have an 06' TDI Jetta with 110,000 miles and a manual transmission I picked up about 6 months ago. I've had zero trouble with it up until recently. I started having a bunch of issues creep up. After some research, it seemed that I might have been bit by the issues with VW grounding. I went through the ground connections under the frame rail behind both headlights as well as the engine ground strap. All of my issues went away for a few days, but are now back in full force. The thing to keep in mind is that all symptoms are intermittent, but when they are present, they are ALL present, and when they are not present, NONE of them are present. The issues I am having are:

• Starter is sluggish
• The engine will high idle at 1,000 RPMs (I've read that this is to compensate for what the ECM sees as a low voltage situation)
• The left rear door lock will lock, but not unlock
• While driving, the speedometer will occasionally drop to zero for just a split second, accompanied by a beeping.
• All lights will rapidly vary in brightness (demonstrating what appears to be a voltage fluctuation). This fluctuation is synchronous with the engine "running rough", which I suppose is not any sort of mis-fire, but rather rapid loading and unloading of load from the alternator. FYI: The alternator clutch-pulley was frozen when I bought the car. I have since replaced it.
• The keyless entry system will sometimes not operate while this is going on. This also is usually predictable because when shutting off the ignition, the interior light dimming will get to a point in the dimming process where they just go off and there is a chattering coming from a control module somewhere. Each time this happens, the tripometer also resets to "0.0".
• The backlights on the power window and lock switches will go out intermittently. The funny thing is the driver's door always happens, but is also sometimes also accompanied by other doors going out with it.

As you can tell, there is a slew of symptoms. I may have even forgot one or two. I am trying really hard to use the KISS method "keep it simple stupid" by coming up with something that all of these issues have in common, but I'm striking out.


On one hand I feel that it could have been one of the lighter gauge ground wires attached to the sub-frame, however, the fact that when all of this is going on, I have a sluggish start points me towards a much higher current path such as the engine ground.


To be clear, all of the ground points that I attacked, I took loose, buffed down with my wire wheel on my Dremmel tool, then applied a no-ox compound, then put back together. None of them were corroded, just had a light "dirty" discoloration. Doing this seemed to clear things up for a few days, but are back.


HELP!!!!!!

This sounds to me like a battery issue. Others and I have found our BRM Jettas to exhibit quite peculiar behaviors when the battery did not appear blatantly bad, but was somehow not quite good enough for the complicated VW electronics. Since this is a new to you car as well, it is possible that at some point in its history there was water damage? That can cause lots of issues, including intermittent ones. Funky contacts at main fuses could cause odd problems.

I did not see in your post any codes shown by your VCDS. I would not be able to own this car without a VCDS, as that is like flying blind.

^^^A marginal battery will cause intermittent electrical issues. If it's older than 3 years, I'd replace it w/o even bothering to charge. OEM batteries seem to work well, are priced competitively, and IIRC, still come with a 4 year full replacement warranty.