1996 Isuzu warning lights on, A/C Off

My battery , 4X4, Brake, and rear ABS lights were blinking on and off, got it checked out and parts folks said it was my voltage regulator in my alternator. As we drove it and the RPM increased the lights went out and the A/C started working, if RPMs got low again lights on dash came on and A/C quit working. Changed the alternator out and now lights are on all the time and A/c won’t work, no matter what RPMs are doing. Can any one give me a glue what’s happening, what to check, etc.

Isuzu what?

I’d double and triple check the wires to the alternator-- one of the quirks of Isuzus is that a lot of the circuits run through the alternator and so the problem with all the warning lights coming on is a pretty common sign of an alternator problem.

Thanks Jack, I called myself checking them but what do you think I might have over looked? It seems like maybe a ground wire is off, how do I check these?

The best way to do it is with a Volt-Ohm-Amps meter. Set it to ohms and you should have very close to zero ohms measuring from the body of the alternator (or ground terminal if it has one) to the body of the truck. If you have more than that, I’d undo the ground strap from the engine to the body, clean if off, and retighten it.