I own a 2002 Oldsmobile Silhouette GLS AWD. It quit charging, so I took the alternator and had it rebuilt (they had to do it twice, didn't get it done right the first time). It also has a new battery in it. After I put the alternator bac in, I drove it up and down the road, and everything seemed fine, no lights, nothing wrong...charging at about 13.5 volts or so...today my wife brought it to town, and a bunch of things started going screwy on it...the ABS, AWD disable, airbag, brake, and battery lights all kept coming on randomly, and then going back off...she also said the heater fan would turn off on its own, but then come back on (she had the switch on the whole time)...when she got to where I work, I put a voltmeter on it, and it read 13.9 volts at idle...we drove it around town, ran a few errands, etc...when I got to Walmart I tested the voltage again, and it read about the same, both at idle and when I had her rev it up and hold it there...on the way there, I noticed that the tach and speedometer are both off, and the fuel gauge was twitching around which all was new...the tach at idle shows about 1300 RPMS, but the motor is at idle, and the speedo reads around 5 mph when stopped...when I got back to work, I checked it one more time, and it was reading 14.5 volts both at idle and increased RPMS as well (can't give you an exact number, because the tach is off)...the headlights also shut themselves on and off randomly as well, whether the switch is in the on position or the automatic position...sometimes it will be fine for awhile, then all the lights start turning on and off randomly on their own...is there a computer that controls all of the these functions somewhere or something? It'* the only vehicle we have that we all fit in now with the new baby, so I really need to get this figured out soon...thanks in advance for the help.

Jeremy

I would recomend take it to autozone or other parts store and have them test your charging system. There tester will test the amperage output and not just the voltage. It free that why i recommend that and not a repair shop. If that all good then its something else. But since they had to rebuild it twice makes me wonder if they got it completly right the second time.

the voltage can be right without having the current carrying capability. you should clean the battery connections, alt connection and grounds. and reassemble with dielectric grease

Another thing I noticed now is that none of the interior lights work, either with the door switches or the switch by the headlights...I was told to measure AC voltage at the alternator, and if it was over 1 volt that the diodes are shot...I measured it this morning and got 31.5 VAC...I wonder if they still didn't get the rebuild right the 2nd time...are diodes something that normally would be covered in an alternator rebuild? I'm still leaning towards something wrong with the alternator, because the only symptom that the van had before I installed it after the 2nd time it was rebuilt was the battery light on due to it not charging...Thanks for all the help.

Jeremy

Take your alternator to autozone for a free check.

Disregard the interior light statement, someone had pushed the override button up on the roof...

Also, I have noticed a pattern as well. I have to have the vehicle in gear and be accelerating for the warning lights to come on and off...it won't do it at idle in neutral or at idle in gear...when you come to a stop with it in gear, everything goes off...I also coasted down a hill at about 25 mph in neutral and nothing came on, so it appears it has to be in gear...This just keeps getting more and more confusing as it goes...also, I am noticing it is doing it everytime I accelerate though, so it is getting less random...

Jeremy

Also, I had the heater fans on high when I was driving it, and when the warning lights start coming on and off, the heater fans start surging really bad as well...

After reading up more on the internet, I found out that for the diode test you measure from the positive nut on the alternator to the positive battery cable, not the negative...after re-doing the test like that, it read 0 VAC...I found a nick in the insulation of the wire that goes from the fusebox to the alternator, and a bare part on the splice, so I re-spliced the wire and electrical taped it up...thought I had it fixed too, it went about 10 miles, but then it started doing it again... >:(...however, there are some differences now...the warning lights don't come on near as often, and I'm not getting the battery light at all anymore, just the AWD disable/ABS/brake, and once in a blue moon the Airbag light...the AWD disable/ABS/brake could be a bad wheel bearing or something else that MAY just have happened at the same time, but when you figure in the airbag light, it doesn't make sense...I'm getting very fed up with this turd...any other ideas would be great. Thanks all.

Jeremy