2008 Chevy Trailblazer High Idle

Asked by Cody Sep 22, 2024 at 12:36 PM about the 2008 Chevrolet Trailblazer 1LT 4WD

Question type: Maintenance & Repair

Replaced the throttle body with a new, OEM throttle
body due to a malfunctioning TPS sensor. TPS code
has gone away, but now the Trailblazer has high idle.

I have tried two different PCM reset methods, but so
far the high idle issue has not been resolved. What is
the correct reset procedure and is there anything else I
can try to identify what is causing this?

2 Answers
311,535

Gene answered 7 months ago

Make sure there are no unmetered air or vacuum leaks, once you have fixed that and if the idle is still high then the ECM needs to be reprogrammed to recognize the new component, as it is still operating on the old presets.

Mark helpful
190

FJ4072327 answered 7 months ago

4.2L I take it? Forced relearn, you can remove fuses #10 and #28 under the hood for about an hour. I usually do this while removing it to clean. Do make sure you hooked the curly hose under the plastic resonator back up, been there. Don't discount a bad TB out of the box either. I replaced mine due to the same issue, did not have a high idle. BUT, I had the 2 fuses out while I swapped it out.

Mark helpful

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