Crazy Electrical Problems

Just got done putting a new turbo in the car. Before starting the job I noticed the battery was getting weak. Car sat for a month before I started the job and by the time I started, the battery was dead (never tried to start the car).

After I got the turbo in I bought a new battery and installed it. Car started and ran great for a day then died for no apparent reason.

Was able to restart the car after some long cranking but then oil light and warning chime came on. Stopped the car and checked the oil. Restarted car. Oil light came on as well as traction control and steering wheel lights. Decided it was probably electrical not oil and drove to parts store. They tested and said voltage regulator on alternator was shot.

Installed new alternator. Car started easily but battery light on. No other lights or warnings.

Took back to store and they tested it & said new alternator was bad. Battery tested good but "needs charge".

Got another alternator and installed it. Same thing. Battery light on.

Tested first new alternator that was "bad" in the car but it tested good on the bench!

So I'm thinking the second new alternator, which tests bad in the car, is probably ok. But I'm only getting a little over 12 volts with the engine running.

Any ideas? Is it possible that the blown voltage regulator on the original alternator cooked the battery in a way that damaged it but leaves it still testing "good"?

Worse, could it have damaged the car electronics in a way that would cause these symptoms?

I've checked my cables, connections and fuses and they all look good.

Thanks!

If this issue is on your 06, then search here for "harness chaffing" threads (there will be numerous) and see the possibilities.

An update. Didn't get a chance to look at it until tonight. I've had a trickle charger on it and battery is measuring 13 volts with everything off and ground disconnected.

I just put an ammeter on it and with everything in the car off, something is drawing 1.5 Amps!

Thanks, aja8888. It sure sounds like a short somewhere but why wouldn't that blow a fuse or burn up a wire?

RV9Factory said:

An update. Didn't get a chance to look at it until tonight. I've had a trickle charger on it and battery is measuring 13 volts with everything off and ground disconnected.

I just put an ammeter on it and with everything in the car off, something is drawing 1.5 Amps!

Thanks, aja8888. It sure sounds like a short somewhere but why wouldn't that blow a fuse or burn up a wire?

Click to expand...

Some of the harness issues just cause problems and throw codes. Please search the forum for harness chafing and you will find examples. Look at this thread:

http://forums.tdiclub.com/showthread.php?t=239987

That's helpful, thanks!

RV9Factory,

You can try isolating the circuits by pulling fuses until the amp draw disappears, then drill down into that circuit. There are a few circuit breaker, short detectors that are on the market too. You would think a dead short would blow a fuse each and everytime. I go thru and fix, check or replace all of the common failure parts on these cars when I get them from the auction. AJA8888 is spot on, the past 3 of my BRMs all had chaffing issues where there was insulation worn off and copper showing. There was also traces of copper oxidization covering all of the wires in that area from water penetrating the harness wrap and attacking the copper. I would check the harness (under airfilter). Since you are in there, clean your grounds too. Behind each headlight, under airbox and under wiper arm in cowl. Cheap course of action that might help resolve the current issue or prevent a new one.

I have a 2004 Jetta that was having some strange electrical issues. It ended up being the fusible link from the alternator. Looking at the link it looked fine, testing it for resistance with a multimeter it tested fine. Underneath the nuts that secure the link the aluminum was all brittle & cracked. The wire to the link is copper, the securing nut is steel, and the link is aluminum; this sets up a corrosion spot. The links need to pass a high level of current; if they cannot do it, it can cause a new battery to not re-charge with a good alternator.