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2004 chevy trailblazer_lt
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Discussion Starter · #1 ·
I just changed my alternator and disconnected the battery. Now my 04' TB idles rough with the AC or Defroster on. When selecting the AC on, the idle will increase then reduce, cycling back and forth then will eventually stall. It seems to run fine without the defrost or AC on. Anyone know what the problem is and how to correct it? Thanks
 

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2003 gmc envoy_slt
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7,190 Posts
:tiphat Welcome :tiphat :iagree: The computer learns to run with a dirty throttle body. When you disconnect the battery it resets the PCM to factory settings and "forgets" the tb is dirty. The tb needs a cleaning.
 

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2004 gmc
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And don't ignore the instruction when it says to remove the battery cable again. That forces another relearning process with the clean throttle body, and ensures nobody comes along and turns the ignition on if you have the TB connected. The butterfly valve motor would fight your pushing on it, and either cut you badly (the edge of the valve is SHARP!) of burn out thestepper motor.
 

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2003 chevy trailblazer_ls
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5,268 Posts
I concur with all the posters.
 

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2004 chevy trailblazer_lt
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Discussion Starter · #6 ·

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2004 chevy trailblazer_ls
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49 Posts
Rough idle

Hey, I had the same issue in my 04 TB I changed the fuel filter..cleaned injectors..changed plugs...cleaned throttle body..and ultimately came down to a bad coil pack!
 
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