I have a 1987 Chevy Bonaventure G30 5.7 TBI. Started with classic bad alternator signs. Dead batteries. Jump starts. After a jump start, the van will die eventually after removing the jumper cables. While the engine is running, disconnecting the battery positive terminal will immediately stop the engine. No difference in voltage on the battery with the engine running or not. Went out and bought a new alternator. Exact same problem with new alternator installed. Brought the old alternator to be tested. It tested good. Reinstalled the old alternator. Returned the new one. Research on the interwebs says the next thing to check is the fusable links. There were 3 14ish gauge ones and a much larger gauge one all near the driver’s side firewall. All four checked out 0.00 on the ohm meter. I’m stuck. I dint kbow what else to check. Any help?
Cables can go bad, check the black cable for swelling, and the connection to the engine block for corrosion.
Does the alternator/charging system warning light come on when the ignition switch is turned on?
Does this '87 have a regulator separate from the alternator?
Please excuse the ignorance of the question. I’m unfamiliar with that vehicle, however I do know that years ago many vehicles had separate regulators.
There is a small short ground wire and a longer thicker wire going under the engine. All ends of these wires look great. I found one of the wires that hooked to the starter was loose while I was under there. Tight end that. No difference. The voltage drops while idling .01 to .03 volts per second until the engine dies right before 11.00 volts.
No, I don’t believe it has ever come on before or after the alternator started acting up
I kind of thought that too but the person who tested the alternator at AutoZone seems to think that the alternator has the regulator built in.
If the alternator/charging system warning light doesn’t come on, it either means there’s no excitation voltage getting to the alternator, or the bulb is burnt out.
Here is the alternator we bought that match the one that is inside the van now https://m.autozone.com/batteries-starting-and-charging/alternator/duralast-gold-alternator/chevrolet/g30/115395_223843_0?location=
You need to have 12 volts on all three wires when the engine is running, test to see if one of the wires has no power. The brown wire should have 12 volts when running to switch on the voltage regulator to cause the alternator to charge.
Sorry I did not update sooner. My son gave up on us trying to fix it ourselves and called a mobile mechanic buddy. The problem was a 20 amp fuse under the dash with all the rest of the fuses. I felt dumb for missing it hehe.