electrical problem

[moose5569]

Does anyone know why a 96 suburban 4x4 with brand new alternator, that tested good, loose voltage when front and back ac on high and head lights on?

[tlperry68]

You are probably drawing as much curent as the alternator can handle.

[silveradotrailblazer]

I had a 96 Suburban and it did the same thing until I installed a POWERHAUS altenater. I also used to eat batteries, so I also installed a Optima Red battery. You really dont need the yellowtop Optima unless you have extra lights or a winch etc. The Red top also has a longer warranty. The POWERHAUS is a direct replacement.

[One Bad Chevy]

Yea you might be maxing out your alternators amp output. you might need a higher output alternator. I use a 200amp on my truck and powers anything i could hook to it. Also the voltage regulator might not be functioning properly. My duramax had that problem when put under big loads.

[Jimmiee]

You are probably drawing as much curent as the alternator can handle.

Zactly! If you want to see the real output of your alternator start up the engine and attach a volt meter to the B+ BATT terminal of the alternator. If you can't do that then just use the battery terminals. Now turn on EVERYTHING, Lights, A/C, Stereo, Rear Window Defogger, Fog Lights and anything else that has an on switch. Run the engine up to 2000 RPM and look at the voltage. It should be at least 14 Volts in round numbers. Rule of thumb is 2 Volts above base battery voltage.

Before you condem the alternator clean the battery terminals and ground cables. Make sure the alternator belt is not slipping.

[Chris Miller]

I ran into this problem a couple of times on a '94 suburban. Turned out to be a bad ground strap on the passenger side frame rail, about 6 inches behind the upper control arm. It was caked with oil from a bad pressure switch. Replaced the ground strap, and it never had a problem since.