oldtruckguy

1998 Silverado, 350. When electrical load is placed on system the dashboard charging indicator shows charging drop. The more load, the more it drops. It recovers but everything that is in use momentarily loses power, not completely but enough to notice. I had the electrical system tested at an auto parts store for what that is worth. Tested ok. I'm thinking alternator but want some other opinions. Thanks for the help.

jfmorris

I would look at the grounding straps, and other electrical connections under the hood. A bad path to ground or degraded electrical connection can reduce the current you can pull, and cause voltage drops under load. I'm not sure what the auto parts store is testing, but if it's alternator and battery, that won't tell you anything beyond those two components, unless it includes a load test of some sort.

If all the wiring looks good, and the voltage drops under load, it is certainly possible that the voltage regulator, which is built into modern alternators, is going bad. When I was a teenager, I had a car that blew the voltage regulator almost yearly, and I would start noticing that the headlights would brighten and dim based on engine RPM. The voltage regulator used to be a separate component under the hood, but some idiot back in the mid to late 70's decided to integrate it into the alternator, requiring you to replace the alternator in order to replace the voltage regulator...

My 1996 C1500 had a bad starter, which the auto parts store people tested as good recently. I insisted on going ahead and getting a new one anyway, and carried it back to the house, and my truck was cranking again 20-30 minutes later. So I don't have a lot of faith in the abilities of folks working behind those counters these days.