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Discussion Starter #1
Has anyone experienced this happen to them. When stepping on the brake (like at a stop light) with the truck in gear the RPM drops to about 500 to 600. Normal right! Every so often the RPM's jump up to about 800. Is this normal? And when I say every so often I mean every 20 seconds or so. Now I have been monitoring this for a couple of weeks and it does it when the truck is cold, warm or hot. Any thoughts? Trip to the dealership? I tried to search for a problem like this but came up empty.
 

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I was wondering that as well. Just havent posted about yet for everyone to coment about. I see this all the tim when coming to a red light, stop sign. I thought it was a symtom of the sticky gas pedal, but even with the gas pedal fixed, i guess that it can be ruled ou, maybe? Anyways I think that brake booster is assisted by the engine's power hydraulic's something like that. Causing the dips in the rpm's. That would be the most logical with the engine under a load and has to compensate when the brake is applied.
 

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A/C pump cycling will cause this when in A/C mode or defrost mode for the windshield. Check your knobs and see if these conditions exist.
 

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Discussion Starter #5
I'm going to see if it still happens when the defrost is off, we have a couple nice warm days coming up. thanks for the replies.

Shack
 

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Yea if i got the A/C or defrost on it does that or when its cold warming up in the morning the RPM will change every so often.
 
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