1983 Buick Skyhawk 2.0l engine. Alternator will not turn on. Have bench checked both the battery and the alternator and both are good. Disconnected wiring and checked for continuity, all good. Checked wires for chaffing, all good. Cleaned all contacts and grounds. Ensured fan belt is tight. The fusible links (A, B, & G) associated with the starting/charging system are all good. With engine running and an external voltage meter connected, I have yanked and wiggled all wires from the dash to the alternator with no voltage change. Tried running a wire directly from the battery + post to alternator terminal 1 with no effect.
About 10% of the time the alternator will turn on, but only when the car is first started. When that happens it will usually charge for the entire drive. Usually, once charging, if I turn on the lights the charging will stop. Once, the charging stopped as soon as I opened the driver's door.
When I first start the car, if the alternator turns on, the volt meter does not immediately go to 14 volts. Instead it climbs from 12 to 14 in about a second or two.
GM service manual says to check for voltage at terminals 1 and 2 of the alternator when the key is turned to run with all connections attached. Manual only says they should read more than zero. Terminal 2 reads 12 volts, terminal 1 reads 3 volt. If I disconnect this plug, both terminals read 12 volts.
I understand the voltage on terminal 1 is what turns on the alternator. I suspect that the voltage or amperage going to terminal 1 on the alternator is being blocked or drained off somewhere, but can't confirm that. The Gages fuse supplies the voltage to terminal 1 and several other systems. Could a fault in one of those systems affect draw enough current to not allow the alternator to turn on, but not blow the fuse?
After driving home I noticed the volt meter in the dash reads low. With engine running I check battery voltage at the terminals with external meter and get 10 volts. Turn off engine and voltage goes to 11.5.
Comments:
Oct 21, 2009
- Battery is new. When problem first started I had it checked and it was questionable so I replaced it. Did not affect charging problem.
Measured voltage at alternator is 12 VDC.Oct 21, 2009
- Internal regulatorOct 22, 2009
- Correct on funny answers. I've had a local "experts" tell me the problem is the blocking diode is open or the starter solenoid is shorted. One told me the fuse is blown and I would still read voltage with it blown.
I'm in a smaller town with mostly questionable mechanics. Most have you drop your car off and they'll get to it eventually, sometimes weeks later. There is a GM dealer, but their service department told me the recalls GM notified me of do not apply, even though my VIN fell in the recalled range. Next town with mechanics is 75 miles away. You can see why I do my own maintenance. There is 1 mechanic I use when the problem is beyond my capabilities. I still have to correct or have him correct his work.
The part store guy is a friend. Checked both battery and alternator. Regulator is inside alternator and was checked as well. All checked good. Due to ongoing problem, he "warrenty" replaced my alternator and battery. Problem continues.
Have wiggled and twisted every wire and connection I can reach both under the dash and hood. I know most wiring problems are at the connections, where the wires flex and get broken strands inside the installation. With that in mind, I trimmed back all the alternator wires and put new ends on them. No effect.
I disconnected the wire going to terminal 1 on the alternator and ran a wire straight from the battery + post to terminal 1, basically by passing all the wiring from the fuse through the gauge and blocking diode. Again, no effect.
I do suspect something might be siphoning off enough current to keep the altenator from turning on.
What problems external to the alternator can keep the alternator from turning on?Oct 26, 2009
- Just an update. I ran a wire straight from the battery to the terminal 1 on the alternator with no effect. Disconnect terminal 1 completely and the alternator turns on and charges. Isn't supposed to! Can't leave it that way as it can lead to an overcharge condition. Have also realized that the GM service manual I've been using is grossly incorrect on the wiring diagrams. So I am visually tracing all the wiring. Problem is no matter what I do, I have to be able to drive the car the next day. Good thing I own a battery charger.Nov 15, 2009
- SUCCESS!!
Not sure why?
Had alternator bench checked again and it checked good. Put it back into the car and took car to a mechanic. Checked good though all checks to include static loads and cranking. All wiring checked good as well. Car has been working good ever since.
Found a lot of little things, none of which should have caused my problems. Perhaps the total of them all did.
Appreciate all the advice and tips everyone gave me.
Thanks to all of you.
Expert
