I had everything working for over a week! Then yesterday Wiff of burning

[Guest Richard D]

Noticed the electrical problem detected indicater came on while I was trying to get home and volt meter had gone from straight up (12 O'clock) to 9 O'clock. Turned off AC lowered windows volt meter stayed at 9. When I got home I would tap the gas and it would jump to 10 O'clock, with no extra load at idle it was showing 12.4 volts. Left everything to cool off. In about 2 hours I hooked up the meter and it showed 12.5. When car started it went to 13.9 volts, turned on AC voltage went to 13.8, headlights on 13.7 all at idle. Drove the car a few miles to heat up alternator above 1,500 rpm voltage stayed at 13.8. Went home opened hood got whiff of burning smell again, got my nose as close as I dare, it is hot under the hood the odor does seem to be from the alternator. Remanufactured Delco lifetime warranty $125.00. I noticed that the BCM controls the regulator in the alternator,thinking of replacing the alternator first,if problem reoccurs then the BCM. Agree? Disagree? Have no idea? All ideas gratefully accepted.

Thanks to all,

Richard

1990 coupe.

[padgett]

Sounds like either a shorting diode or a bad regulator (both in alternator) to me.

 

Might also be a shorted cell in the battery so I'd check both. What does the battery read with the engine off ?

[bikemikey]

This is probably not your problem, but I thought I'd mention this anyway. I had similar symptoms with the alternator. On a cold engine the alternator worked fine until it warmed up, then down the road the red warning light would come on. The voltage would go up and down acting like there was something wrong with the battery . I took the alternator to a reputable shop and they said it was okay, I also checked the battery connections, same problems. It ended up being a bent pulley, I changed out the alternator, problem solved. You probably have something wrong internally with the alternator, but I would check out the pulley just to make sure there is no wobble. Just a thought.   

[bikemikey]

I forgot to mention, I also changed out the belt tensioner. My 89 had 118,000 on it with what I think was the original tensioner. I also checked all the other pulleys to make sure they were running true.

Mike  

[Guest Richard D]

Thanks for your help. What has happened to GM, an alternaror that fails at just under 150,000 miles. This morning I stuck my nose at the alternator vents and the same burning smell is present, so after 150,000 miles it owes me nothing. Rock Auto has a Delco reman with lifetime warranty for $99.79 + $15.00 core charge. New Delco $189.00. I think I will go for the Delco reman. Unless Padgett or someone else recommends the new Delco. Back in the 1970s if your car lasted 100,000 miles that was amazing.