1994 Other GMC Models Battery Light and gages

1994 GMC
81,000 MILES • V8 • 2WD • AUTOMATIC
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FIRDOG7
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  • 1 POST
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.
Aug 16, 2009 at 12:00 PM
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MICKEY-D
  • ✓ASE Certified Mechanic
  • 304 POSTS
  • ASE Certified Mechanic
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.
Jan 11, 2010 at 10:21 PM
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