Pcm ?

[MIJimmy]

I have a 95 Jimmy some times when I start it the idle will go up to 2500 or 3000 rpm. I was told idle air valve. Iwas also told the next time it idles correctly unplug idle air valve it worked great. I wanted to fix the problem so I got the valve worked for 2 days an started doing it again so I unpluged it again. Could it be bad pcm? Any help would be great.

 

[Molson02536]

I have a 95 Jimmy some times when I start it the idle will go up to 2500 or 3000 rpm. I was told idle air valve. Iwas also told the next time it idles correctly unplug idle air valve it worked great. I wanted to fix the problem so I got the valve worked for 2 days an started doing it again so I unpluged it again. Could it be bad pcm? Any help would be great.

Common problem when the IAC (idle air control) valve is dirty with carbon build up. What happens when you turn the ignition key on to start the engine, the IAC will open up and should close when the engine starts to moderate the RPM to idle the engine. Start with trying to clean the IAC with throttle body cleaner through the throttle body and the IAC passageways. 80% of the time, this will fix the problem, but if the IAC is to badly gummed up with carbon. You may have to replace the IAC. Good luck and keep me posted.

 

[MIJimmy]

Common problem when the IAC (idle air control) valve is dirty with carbon build up. What happens when you turn the ignition key on to start the engine, the IAC will open up and should close when the engine starts to moderate the RPM to idle the engine. Start with trying to clean the IAC with throttle body cleaner through the throttle body and the IAC passageways. 80% of the time, this will fix the problem, but if the IAC is to badly gummed up with carbon. You may have to replace the IAC. Good luck and keep me posted.

Molson I had already replaced the IAC so I sprayed the passage it helped so I will do it again. Now it idles high after driving stoped at drive through an idle went up to 1500 wouldn't come back down until restart.I also get intake air temp high input with check engine light. One more ? my defrost stays on weather it on floor blend or defrost. I check the vac lines on the control knob thier good I was wondering how to get to the defrost door. I'm changeing radio so i would like to do it then any help would be apreciated

 

[Molson02536]

Molson I had already replaced the IAC so I sprayed the passage it helped so I will do it again. Now it idles high after driving stoped at drive through an idle went up to 1500 wouldn't come back down until restart.I also get intake air temp high input with check engine light. One more ? my defrost stays on weather it on floor blend or defrost. I check the vac lines on the control knob thier good I was wondering how to get to the defrost door. I'm changeing radio so i would like to do it then any help would be apreciated

Recheck your wire leads and harness to your IAC and IAT since they seam to both be giving you problems. Look for any damages and corrosion and repair or replace.

Here are pictures for your Vacuum lines to your 95 jimmy, the pic's say 94 but your 95 is an odd ball year and uses the 94 vacuum line system.

http://i11.photobucket.com/albums/a187/swartlkk/general automotive/94_vac_overall.gif

http://i11.photobucket.com/albums/a187/swartlkk/general automotive/94_cruise1.gif

http://i11.photobucket.com/albums/a187/swartlkk/general automotive/94_4wd1.gif

http://i11.photobucket.com/albums/a187/swartlkk/general automotive/94_hvac1.gif

Also here there is a Technical Service Bulletin that addresses it, here's a copy paste of the TSB:

#03-01-38-009: HVAC Mode Switch Inoperative or Stuck in Vent Mode, Oil in HVAC Control Head and/or Vacuum Lines (Replace Transfer Case Vacuum Switch and Contaminated HVAC Components) - (Jun 25, 2003)

Subject:
HVAC Mode Switch Inoperative or Stuck in Vent Mode, Oil in HVAC Control Head and/or Vacuum Lines (Replace Transfer Case Vacuum Switch and Contaminated HVAC Components)

Condition
Some customers may comment that the HVAC mode switch may be inoperative or stuck in the vent mode. After some diagnosis, oil in the HVAC control head and/or vacuum lines may be found.
Cause
When the transmission or transfer case heat up, the oil may expand and find its way into the transfer case vacuum switch. This oil expulsion may cause the vacuum switch seal to fail and allow transfer case oil to be drawn into the HVAC vacuum lines.
Correction
Replace the transfer case vacuum switch. Refer to the Transfer Case Vacuum Switch Replacement procedure in the Transfer Case sub-section of the Service Manual. Also, replace all contaminated parts in the HVAC system.

Parts Information

Part Number 15664811
Description Switch -Transfer Case Vacuum
Parts are currently available from GMSPO.

Good luck and keep me posted eh.