1994 Lexus GS 300 apparent electrical short

  • 1994 LEXUS GS 300
  • 6 CYL
  • 2WD
  • 150,000 MILES
There appears to be a short somewhere in the electrical, and I'm hoping for some suggestions to find it.

- The first symptom was turning the ignition would sometimes not start the car. Trying again, the car would start fine.
- Next the battery light on the dashboard started coming on. That happened to coincide with cold weather, so I thought at the time it was related to that.
- Then one morning turning on the ignition, the car started fine and the engine was running, but the dash lights were very dim and the car wouldn't shift into gear. I measured directly at the battery terminals and saw 5V (with the engine running). Half hour later I tried the car again and it ran normally.
- A few days later, after the car had gone about 40 miles, the radio suddenly started making a loud buzzing at maybe around 100Hz, then dropped out entirely after about 10 seconds. As I continued down the road, the dash lights continued to dim and I started loosing electrical systems one after another. I tried shutting off heaters and whatever else, but saw no effect. The transmission eventually stopped shifting reliability, and finally the car stalled after several miles as I tried to make it up a steep hill. Up to that point, the engine was running fine. Immediately trying to restart the car, it just made a clicking sound like a dead battery. But after about 15 mins I tried again, and the car started normally and ran fine.

The battery is new and usually has a healthy 12.5V charge. I'm guessing the problem is an intermittent short somewhere that is enough to drag the voltage down, but not enough to blow a fuse. It's tough to diagnose, because the problem occurs randomly. Next time this happens, I was planning to pull over and just start pulling fuses live until the headlights spring back to normal glow. Not ideal, but I'm at a loss. Any ideas would be greatly appreciately.
Do you
have the same problem?
Thursday, February 18th, 2010 AT 1:33 PM

1 Reply

Much simpler than all this. The engine block leaked oil into the alternator and caused it to fail.
Was this
Thursday, February 25th, 2010 AT 7:23 PM

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