89 Camaro I-ROC V-8 5.7
New and properly installed: battery, terminals, battery cables, alternator, starter, and drive belt. All check out fine with a multimeter. Now the problem. I start it, let it idle in neutral, everythings fine. But if I shift to reverse (foot still holding the clutch) my volt gauge drops to 9. I put it in first no change but when I start driving, volt gauge drops to 8. I turn on my head lights, light bar, windows, anything and my volt gauge drops to 9. I turn them off or stop doing anything and it goes back to a normal 13.

- My oil pressure gauge drops with my volt gauge. Not by as much but definitley noticable.

-All my fuses check out fine except for the one marked "INST LPS". Either a dead wire or bad terminal. I've tried looking up what it was used for but had no luck.

-Most importantly, all the above started when I replaced my corroded ground cable with a fresh one. After which I replaced my alternator for a good one.

 

Check ALL your ground connections, bat to engine, engine to frame and engine to firewall. INST LPS is for instrument lamps (gauge lights). HTH!

 

Didn't even think to check those. I'll take care of that first thing in the morning. Thanks

 

Don't trust the dash gauge. Hook up a real volt meter and see if voltage is really dropping or if the gauge is just flaky.