1994 Other GMC Models Battery Light and gages

  • 1994 GMC

Electrical problem
1994 Other GMC Models V8 Two Wheel Drive Automatic 81000 miles

I have a 1994 GMC 3500HD with a boom mounted. (Old NYNEX truck). There is a an auxillary battery mounted in the engin copartment. Inside the cab is a botton to use the auxillary battery. When I start the engine it runs very rich and loud, and the volt meeter gauge is at the 10v area. If I press the auxillary battery botton it seams to switches over and the volt meeter gauge goes up to 13V+. If I step on the breaks it switches back. If I use the turn signal the gauges start going crazzy, up and down. The alternator is brand new and I just replaced the primary battery which seams to help with the volt meeter staying higher. When I use the the turn signal the gauges still jump back and forth.

Do you
have the same problem?
Sunday, August 16th, 2009 AT 12:00 PM

1 Reply


You need to make sure that_BOTH_batteries are in good shape, and check all your grounds, battery to engine, engine to frame, and engine to firewall. They are really important.

Was this
Monday, January 11th, 2010 AT 10:21 PM

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