Jump to content
  • Sign up for FREE! Become a GM-Trucks.com Member Today!

    In 20 seconds you can become part of the worlds largest and oldest community discussing General Motors, Chevrolet and GMC branded pickups, crossovers, and SUVs. From buying research to owner support, join 1.5 MILLION GM Truck Enthusiasts every month who use GM-Trucks.com as a daily part of their ownership experience. 

Sign in to follow this  
dzrick

Idle Relearn 2003 Trailblazer

Recommended Posts

It was suggested that I post this here due to the lack of veiws in the ask a tech section.

 

My main question is what controls the idle speed when the AC or defroster is on in a 2003 Trailblazer straight 6 cylinder. This is my sisters truck and not having a working defroster in upstate NY in the winter isn't fun.

 

 

The rest below is just what we've done to the truck in the last couple of months in case it might have caused the problem.

 

 

This might be a little long but I want to give you all the facts as I know them.

 

Awhile back, maybe 2 months ago we had to replace my sister's battery due to a bad cell after changing it we found that the altenator wasn't charging so we changed that as well.

 

Now the facts get a bit fuzzy, she can't remember if the defroster and AC bogged the motor down before all this or not or if she doesn't know because she wasn't using either of these until recently.

I do know that until we changed the heater resistor today that she was only able to use the highest fan speed (5 I believe) but when in the the AC setting and the defroster setting would stall the truck or come very close to stalling it.

 

Now she has all the fan speeds but when we put it in defrost or AC it still boggs the motor down sometimes right down to a stall, it'll start right back up but I'm thinking there must be something that idles the motor up when either the defroster or AC is used that isn't doing it's job.

 

Can you tell me what it's called and where it's located or if my thinking is wrong, straighten me out.

 

Thank you for any help you can offer,

Rick

Share this post


Link to post
Share on other sites

IAC "idle air control" may be carboned over, assuming your vehichle has one. It would be located on the throttle body. IDK, just a thought.

Share this post


Link to post
Share on other sites

pennzoil29, if what I saw was the IAC it isn't the same as my 98 GMC and the guy that is helping me isn't up to date on the newer vehicles. He said that if what we were looking at was the IAC it didn't look like it was something that could be taken apart for cleaning.

 

He admits he might be wrong but he hasn't steered me wrong yet.

 

Somebody here has to know for sure. I really don't like the idea of her driving around with fogged up windows so if we have to I guess we'll have to take it in to get it fixed.

Anyone else got any ideas?

Share this post


Link to post
Share on other sites

Rick,

 

I found this by doing a search on the net for idle relearn....hope it helps.

 

 

When you're having problems, the first thing worth trying is the idle lean procedure. The ECM uses non-volatile memory to keep track of the IAC position when the engine and ECM are turned off.

Each car has a unique IAC value that takes into account the condition of the sensors, air and vacuum passages, etc.

Whenever the ECM loses battery power (which clears the stored IAC position) or significant changes to the system (e.g. sensors are replaced) it is a good idea to perform the idle learn procedure.

 

The procedure in the service manual was superseded by a more recent service bulletin.

 

It says to turn the car complete off (remove the key), remove power from the ECM for 20 seconds and then start the car.

Let it idle for 10 minutes.

Shut it off for 20 seconds and then start it and let it run for 5 minutes.

Shut it off again and you're done.

  • Like 1

Share this post


Link to post
Share on other sites
Rick,

 

I found this by doing a search on the net for idle relearn....hope it helps.

 

 

When you're having problems, the first thing worth trying is the idle lean procedure. The ECM uses non-volatile memory to keep track of the IAC position when the engine and ECM are turned off.

Each car has a unique IAC value that takes into account the condition of the sensors, air and vacuum passages, etc.

Whenever the ECM loses battery power (which clears the stored IAC position) or significant changes to the system (e.g. sensors are replaced) it is a good idea to perform the idle learn procedure.

 

The procedure in the service manual was superseded by a more recent service bulletin.

 

It says to turn the car complete off (remove the key), remove power from the ECM for 20 seconds and then start the car.

Let it idle for 10 minutes.

Shut it off for 20 seconds and then start it and let it run for 5 minutes.

Shut it off again and you're done.

 

 

Thanks Jim,

 

I should've thought to do a search myself. I appreciate your effort whether it fixes it or not.

I'll give this a try tomorrow night and let you know how it goes.

 

Rick :D

Edited by DZRick

Share this post


Link to post
Share on other sites
Rick,

 

I found this by doing a search on the net for idle relearn....hope it helps.

 

 

When you're having problems, the first thing worth trying is the idle lean procedure. The ECM uses non-volatile memory to keep track of the IAC position when the engine and ECM are turned off.

Each car has a unique IAC value that takes into account the condition of the sensors, air and vacuum passages, etc.

Whenever the ECM loses battery power (which clears the stored IAC position) or significant changes to the system (e.g. sensors are replaced) it is a good idea to perform the idle learn procedure.

 

The procedure in the service manual was superseded by a more recent service bulletin.

 

It says to turn the car complete off (remove the key), remove power from the ECM for 20 seconds and then start the car.

Let it idle for 10 minutes.

Shut it off for 20 seconds and then start it and let it run for 5 minutes.

Shut it off again and you're done.

 

I just wanted to thank you Jim and let anybody else that might have this problem that the info above worked.

 

Rick

Share this post


Link to post
Share on other sites
Rick,

 

I found this by doing a search on the net for idle relearn....hope it helps.

 

 

When you're having problems, the first thing worth trying is the idle lean procedure. The ECM uses non-volatile memory to keep track of the IAC position when the engine and ECM are turned off.

Each car has a unique IAC value that takes into account the condition of the sensors, air and vacuum passages, etc.

Whenever the ECM loses battery power (which clears the stored IAC position) or significant changes to the system (e.g. sensors are replaced) it is a good idea to perform the idle learn procedure.

 

The procedure in the service manual was superseded by a more recent service bulletin.

 

It says to turn the car complete off (remove the key), remove power from the ECM for 20 seconds and then start the car.

Let it idle for 10 minutes.

Shut it off for 20 seconds and then start it and let it run for 5 minutes.

Shut it off again and you're done.

 

I just wanted to thank you Jim and let anybody else that might have this problem that the info above worked.

 

Rick

 

Thanks for posting back. I'm glad you got the vehicle fixed.

Share this post


Link to post
Share on other sites
Rick,

 

I found this by doing a search on the net for idle relearn....hope it helps.

 

 

When you're having problems, the first thing worth trying is the idle lean procedure. The ECM uses non-volatile memory to keep track of the IAC position when the engine and ECM are turned off.

Each car has a unique IAC value that takes into account the condition of the sensors, air and vacuum passages, etc.

Whenever the ECM loses battery power (which clears the stored IAC position) or significant changes to the system (e.g. sensors are replaced) it is a good idea to perform the idle learn procedure.

 

The procedure in the service manual was superseded by a more recent service bulletin.

 

It says to turn the car complete off (remove the key), remove power from the ECM for 20 seconds and then start the car.

Let it idle for 10 minutes.

Shut it off for 20 seconds and then start it and let it run for 5 minutes.

Shut it off again and you're done.

 

I just wanted to thank you Jim and let anybody else that might have this problem that the info above worked.

 

Rick

 

 

 

No problem. Glad to help.

Share this post


Link to post
Share on other sites

I'm having the same rough idle my rpm is going up and down but when it's driving it is ok. And yes my battery cable was disconnected for over 24 hrs.

Share this post


Link to post
Share on other sites

Check for stored codes. Try cleaning your MAF and throttle body

 

What vehicle and engine?

Share this post


Link to post
Share on other sites

I just wanted to thank you Jim and let anybody else that might have this problem that the info above worked.

 

Rick

Hey how many time did you try that and how exactly did you do it because I am having a hard time getting mine to idle right

Share this post


Link to post
Share on other sites

Check for stored codes. Try cleaning your MAF and throttle body

 

What vehicle and engine?

I clean the throttle body it is a 2003 Chevy Trailblazer with a 4.2 engine

Share this post


Link to post
Share on other sites

Hey how many time did you try that and how exactly did you do it because I am having a hard time getting mine to idle right

 

 

Wow, this was 6 years ago. :)

 

I followed Jim's instructions as closely as possible and thankfully it worked on my first try.

As far as how exact you need to be time wise, I'd think as long as you use the times as minimums you should be ok.

 

I wish I could be more helpful.

 

Her '03 is long gone, she's got a 2012 now.

 

Good luck to you Yves, hope you get yours figured out soon

Edited by DZRick

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  



×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.