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Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1685
Experience:  GM Grand Master Technician 2007. 14 year experience.
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Gmc G2500 Vandura: 1988 gmc g2500. Lopes at idle. Lights

Customer Question

1988 gmc g2500. Lopes at idle. Lights dim and brighten during lopes. Battery charge gauge on dash moves up and down to. Put on new plugs, wires, dist cap and change.... Any clue? No codes...but service engine soon light displayed.
Submitted: 2 years ago.
Category: GMC
Customer: replied 2 years ago.
Also....when the accelerator is pushed at idle and the engine revs up....the light dimming and the battery charge gauge still lopes at the same speed as the accelerator not being pushed.
Customer: replied 2 years ago.
It is a camper van.
Expert:  JFN1 replied 2 years ago.
I would probably start by removing the serpentine belt, and seeing if the problem is still there without the alternator spinning. It's possible that the alternator has failed and is introducing AC voltage into the wiring harness, which makes the computer pretty unhappy. A simple test is to just remove the belt, start the engine, adn see if it still does it.