Strange Electrical problem.

[bigcat488]

I have a 91 Explorer, 500,000 miles on it. Since I bought the truck the volt meter swings rapidly form 11 to 15 volts. I bought the truck at 180,000. The alternator, battery, and starter have been replaced several times. The problem may go away for a little while but them comes back. I replaced the computer at 250,000 and have put both computers in to not avail. I have run an alternate ground to the altanator, did not help. I have cleaned all the connections on everything and used dielectric grease, did not help. Battery cables have been replaced, did not help. I am open for any suggestions. I have verified that the meter is working and have also added a digital after market volt meter. I have also verified with a Fluke 77 multimeter. We love the truck and the wife still drives it to work. Trucks eats a battery a year.

 

[BrooklynBay]

I've moved your thread to the stock 91-94 section. What brand are all of these alternators? The latest one might be defective.

 

[DsrtExplorer]

I have the same problem and have replaced the same things while troubleshooting: alternators, regulators, battery cables, etc. It only happens at an idle and the lights pulse at the same rate as the meter swings. I even went with a 130 amp alternator hoping that would help, but still the same thing. I have even went with different ignition wires thinking there may be an induced voltage problem, and moved wire bundles around under the hood, but still the same thing. Once off idle, everything evens out. I would sure like to figure out the problem....

 

[YBCold]

maybe key off drain? just use ur VOM to measure current drain.