'94 Century eating alternators & blinking airbag light

buick
lights
alternators
century

#1

Hi all! I’ll just dive right in, but I thank you all in advance for your time. The car is a 1994 Buick Century, 3.1L V6, ~ 80k miles.



Four months ago she wouldn’t start, so I got a new alternator and battery put in. A month later, while on a short road trip, the dashboard lit up like a Christmas tree the whole drive home (ABS, airbag, check engine, battery) and the voltmeter bounced around from mid-high to red-zone high. Thinking it was a bad reman, the alternator was replaced again when we got home. A few weeks went by and all seemed to be going well with the new alternator until, after driving around the city for a while, the airbag light started blinking intermittently. Accompanying the blinking, the battery gauge again was bouncing around. Eventually, when accelerating from a stop, the car stuttered when moving forward, the battery light flickered, and the ABS light stayed on. Worried that I’d burn up another alternator, I had a mechanic look at it before my next trip. He checked the alternator/battery loads and pulley and said that nothing looked wrong.



On the next trip, the intermittent airbag light blinking and voltage fluctuation returned as well as a single episode of stuttering from a stop… these things all only seem to happen after at least an hour on the road.



TO RECAP: Voltmeter gauge steady sometimes, bouncy other times… but usually too high. Airbag light blinks intermittently (seems to happen only after car is warm). Sometimes (rarely) the car will jerk from a stop, at which point the ABS light stays on. No check engine lights. Battery and alternator are new. Same problems (voltmeter in red, warning lights) occurred with last alternator until it burnt up.



It seems like a voltage regulation / alternator problem, but the same symptoms occurred with two different alternators (with two different internal voltage regulators). I suspect that there is some electrical problem (short?) that is causing the fluctuating voltage and the tendency for the car to burn up alternators so frequently. However, I don’t know much of anything about cars. Does that sound right? If so, where do I even start?


#2

There may be a intermittent connection problem with the battery ‘sense’ lead that ties between the battery and the rear side of the alternator. A bad connection there could cause the alternator to think the battery charge level is low and thus make the alternator work harder than it should have to. The trouble could also be in the main output lead to the battery. Checking the voltage on those leads while the trouble is occuring should indicate where the trouble is at.