1990 alternator issue??

[walt113]

Yesterday when I got home my BRAKE and BATTERY lights were on. My battery is fairly new but had a bit of corrosion on it which I cleaned off with baking soda/H2O and when I started it back up to pull into the garage, no lights. This AM when I started up, the lights were on again. I made it to work OK and asked questions and the alternator was voted as the most likely problem - I did check all the fuses and they are OK. I left work early to get an alternator and after driving just a minute or so, the lights went off again. I got home and checked the battery with a meter and it was reading around 14 amps while running. I had another errand to run - for a while the lights were off but came on and on the way home (20 mile trip) they were on the whole time. The amps were 12.33 when I got home - I thought they would be a lot lower. Now the question - is it most likely the alternator - I can't think of anything else. It looks like the lower mounting bolt is not too easy to get to, but not as hard as other stuff I have worked on. Also, the person at O'Reilly said the current alternator was putting out only 30 amps when the lights were off. I'm thinking that's not enough. Thanks much for any help. Walt

[RED91SR5]

Originally Posted by walt113

Yesterday when I got home my BRAKE and BATTERY lights were on. My battery is fairly new but had a bit of corrosion on it which I cleaned off with baking soda/H2O and when I started it back up to pull into the garage, no lights. This AM when I started up, the lights were on again. I made it to work OK and asked questions and the alternator was voted as the most likely problem - I did check all the fuses and they are OK. I left work early to get an alternator and after driving just a minute or so, the lights went off again. I got home and checked the battery with a meter and it was reading around 14 amps while running. I had another errand to run - for a while the lights were off but came on and on the way home (20 mile trip) they were on the whole time. The amps were 12.33 when I got home - I thought they would be a lot lower. Now the question - is it most likely the alternator - I can't think of anything else. It looks like the lower mounting bolt is not too easy to get to, but not as hard as other stuff I have worked on. Also, the person at O'Reilly said the current alternator was putting out only 30 amps when the lights were off. I'm thinking that's not enough. Thanks much for any help. Walt

The internal Voltage regulator in the Alternator is going bad. Common problem with these alterntors but fairly easy to change out and relatively inexpensive. I've done it on both AGE coupes and AFE sedans with the alternator still in the car but it is easier if you take it out and do it on a bench. Then you can clean the rotor contacts and check if the brushes need replacing which you might want to do, they are cheap.

[blb]

Originally Posted by walt113

Yesterday when I got home my BRAKE and BATTERY lights were on. My battery is fairly new but had a bit of corrosion on it which I cleaned off with baking soda/H2O and when I started it back up to pull into the garage, no lights. This AM when I started up, the lights were on again. I made it to work OK and asked questions and the alternator was voted as the most likely problem - I did check all the fuses and they are OK. I left work early to get an alternator and after driving just a minute or so, the lights went off again. I got home and checked the battery with a meter and it was reading around 14 amps while running. I had another errand to run - for a while the lights were off but came on and on the way home (20 mile trip) they were on the whole time. The amps were 12.33 when I got home - I thought they would be a lot lower. Now the question - is it most likely the alternator - I can't think of anything else. It looks like the lower mounting bolt is not too easy to get to, but not as hard as other stuff I have worked on. Also, the person at O'Reilly said the current alternator was putting out only 30 amps when the lights were off. I'm thinking that's not enough. Thanks much for any help. Walt

I hope the 14 amps and 12.33 amps quoted above are actually 14 Volts and 12.33 Volts, and yes the alternator needs to be repaired or replaced.

[TRDKAMURI99]

I had the same problem with the brake and battery light on too. I've replaced the alternator and fixed the problem.

[walt113]

Thanks for the replies - yeah it was volts, not amps. If it would have happened over the weekend I might have tried taking it apart and checking the brushes and the VR. As it was, I was in a hurry so I got a rebuilt and put it in. Fairly easy project compared to some and it is running great again.