charging system

I got the red charging system on my 88 a few weeks ago. I got out and heard a squeak from the alt and replaced the bearing in the front. That took care of it for a month or so, but now the light is on pulsing lighter to darker to off. I have a new alt in the trunk for now, but in reading and performing the FSM tests it appears it could be the BCM. The problem I have is that the warning light is never red when I perform the tests, so I am unsure if my gen field is bad or the diodes or the regulator or all of the above. I disconnected the BCM and checked my grounds under the hood and it hasn't come on for over a hundred miles now. Maybe it was a bad connection.....oops I was dreamin. Even when the light is on my volts are 13-15 and my gen field is from 0 to 100. I am assuming 100 is max.

My plan is to drive it until it comes on again and I have time to run the diagnostic procedure with the red light on when I have time. Any other suggestions from the electrical whizzes out there? My headlights go from bright to dim. I assume that is the regulator. One other thing that may or may not be related, the cruise set function quit working and gives me a code. I haven't had a chance to look into it, but that tends to make me wait to see if the BCM is crashing. Any dangers in leaving it as is to pursue what is the real cause, or am I risking a spike in voltage that could cause damage to other components? I gotta get it done before cold weather sets in.

I would go with the alt on this one. The BCM is probably cheaper to replace (less than $100 at Autozone).

My light came on and it turned out to be the connector to the alternator. The lock down clip was broke off and the connector itself was broke, causing a poor connection.

Regarding the cruise control, I would bet on the modulator. If it was electrical it would both throw a code and tell you that there is an electrical issue with your cruise.

If it throws a code only, I would start with the modulator.

It could be the ground(s) usually when you test the altenator, you put the meter probe on the output and find a good ground.... in your case, you are getting good voltage.....

I have found several cars with the ground nuts were not tight. The ground nuts are located on the radiater bulkhead next to the battery. There are slight differences with years, but you will notice several black wires going to a stud and a nut holds them in place. Next to the stud there is a sheet metal screw with more black wires. Tighten both.

Today the car has a definite whine coming from the alternator, so I'll probably swap it out. I forgot to look at the code for my cruise last night. It does indicate and electrical problem and then throws a code, b673. My tab to hold the clip of wires on the alternator is broken as well. It seems to sit on there and stay in place fine, but I might as well see if I can get a good one and solder it in.

Don't solder it in. Go to a junk yard and get a good connector and replace/solder that in.

That is what I meant, Dave, to solder in a replacement clip. FYI when I put the new one in the volts show a nice steady 13.6 -13.7 unlike before where it was wildly fluctuating from 12.7 to 15.7 volts. Anyone know if that's just the regulator? I don't they're too expensive and fairly easy to replace and have a spare for the next time...if the 88 makes it that far. Thanks for advice, members.

On a GM the regulater is in the alternator. If you are satisfied with your current voltage, I would leave well enough alone. My voltage was jumping all over the place as well as throwing a code. I think replacing the clip addressed your regulator issue as well.

I don't explain things that well. I haven't replaced the clip yet. I replaced the alternator because it was whining so loud (reminded me of ex too much) and I don't want it to quit in a bad place or a rainstorm or some inopportune time. The voltage changes I am guessing are due to a regulator about to go? Or could it be diodes or even armature that is out of round and varying the output too much for the regulator to handle? I am just wondering if it's worth trying to repair it for a spare.