1996 Chevy Tahoe idle problem

1996 CHEVROLET TAHOE
247,000 MILES • 4WD • AUTOMATIC
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MIRANDA A. HIPP
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When I start my truck in park it idles 3000 RPMS, when I put it in reverse the idle lowers a lot, neutral stays about the same , but when in drive the idle goes up again, and in 1st and 2nd it lowers again. can anybody tell me why this is happening? I cleaned the intake and throttle body out, did not seem to make a difference. Also its something is making the battery drain, I am constantly needing a jump and other times it will start all day fine! What's going on? please help!
Mar 21, 2017 at 9:24 AM
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CARADIODOC
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Before we go looking for other stuff, have the charging system professionally load tested by a mechanic, not at an auto parts store. Specifically, we want to know "full-load output current", and "ripple voltage". Let me know what is found.

As a preliminary test, unplug the small plug at the rear / side of the generator. If the running problems clear up, suspect the generator. If that needs to be replaced, be sure to replace the battery at the same time, unless it is less than about two years old. That will reduce the high number of repeat generator failures.
Mar 21, 2017 at 5:22 PM