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1979-1993 & 94 Conv [Subscribe to Daily Digest] |
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Okay, so I occasionally post about my continuing electrical problems. Here I go again!
I used to have low voltage regularly when running. A new (used) 9000 alternator (115A) and a new grounding wire from the alternator case to the engine (I hooked it up to a bold on the throttle body; hope this is okay) seemed to mostly fix that. Now, when things are working, I can get almost 14V with the headlights on. I think this is pretty good. Also, I measure no noticeable voltage difference between the alternator case and the negative battery terminal or the bolt on the main ground point at the radiator.
Now for the problems.
Problem #1: After a cold start in the morning, I'll be driving to work when all of a sudden, the dash lights and headlights will dim, the voltage will drop to ~11.5-12V, and I can't get it back. RPM seems to make no difference. There is no battery light which comes on.
If I turn the car off and start it, often several times, eventually I'll get normal voltage and the lights get nice and bright again.
Note (not necessarily a problem) #2: When starting the car, get the battery light and about 11.5-12v until I rev to 2000RPM or so, when the battery light goes off and the voltage goes up to 14ish volts.
Problem #3. This is the biggest problem and biggest mystery. Usually occurs when the car is warm, but sometimes not. When a large electrical load comes on, voltage drops dramatically. Not all the time, even when the problem is occurring, but usually, while the problem is occurring. When the voltage drops like this, the radio will cut out, accessories will turn off, and occasionally the engine will stall (if idling) or hiccup noticeably if driving. This can be triggered by hitting the brake lights, reverse lights, turn signal, turning on the headlights, the radiator fan kicking on, etc.
Now here are the weird notes:
1. Even when this problem is occurring, the voltage will return to a charging voltage, maybe 13.5V.
2. When the problem is not occurring, everything appears to be running fine, and I can use all of these electrical accessories without trouble.
3. I believe that sometimes the problem starts after hitting a bump in the road, or braking hard.
4. I've never had a situation where even if this is occurring I could not start the car, although I'm now careful to try not to start the car with the lights on or my foot on the brake where possible.
5. If the 'problem' is happening when I start the car, I'll know it immediately because I won't have the battery light; the alternator will be working immediately at startup.
6. If I'm having this issue when I shut the car off and I turn it off only to the accessory position, there will be a noise (hard to describe) when the engine stops; everything electrical will turn off momentarily, then come back on being fed by the battery.
7. The starter is (fairly) new and the problem occurred both before and after the alternator and starter changes.
8. I have repeatedly cleaned the main radiator ground point, changed the ends on the big bundle of black ground wires there, and cleaned the transmission ground point.
9. I do have some RPM-dependent whine coming through my radio speakers, both FM and AM stations; not sure if this whine changes when the 'problem' is occurring.
The car is an '89 900 base 4-door
I have done the taillight ground modificaiton.
HELP!
Thanks to the braintrust!
posted by 209.54.73...
, Wed, 18 Feb 2004 08:02:35
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