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2003 chevy trailblazer_ls_ext
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58 Posts
I found out on the way home at the local dealership that it will cost $116.06+TAX to flash the PCM, and that there is NO way they can tell if it was done previously.

Looks like I'll be saving up for the PCMforless after all!
 

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2005 gmc envoy_sle_xl
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1,029 Posts
I found out on the way home at the local dealership that it will cost $116.06+TAX to flash the PCM, and that there is NO way they can tell if it was done previously.

Looks like I'll be saving up for the PCMforless after all!
You can get yourself a ELM327 scan tool and the ScanXL program from Palmer Engineering and it will tell you what CALID's have been applied to the PCM. A Bosch Tech2 or Snap-On Modis will tell the same. You can then go to the website below and see which CALID's you may need. Afterwards you could use these tools to check and see if they actually installed the calibration.

http://tis2web.service.gm.com/tis2web
 

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2003 chevy trailblazer_ls_ext
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58 Posts
ELM327P v1.3a (PDIP): $19.00 OR ELM327SM v1.3a (SOIC): $19.00

Im totally new to this so I dont know which I would need. What is the difference between the PDIP and the SOIC?

Also, that software is quite expensive. Seems I might as well just get one from PCMforless.
 

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2005 gmc envoy_sle_xl
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ELM327P v1.3a (PDIP): $19.00 OR ELM327SM v1.3a (SOIC): $19.00

Im totally new to this so I dont know which I would need. What is the difference between the PDIP and the SOIC?

Also, that software is quite expensive. Seems I might as well just get one from PCMforless.
SOIC is surface mount - it has flat contact pins and is tiny
PDIP is through hole mount- it has bent pins, designed for inserting into IC sockets and such

You want the latter.

As for the software, you can download ScanXL and use it even though it is not licensed. it will still give you the CALID's however other features will be disabled. There are other free software packages out there that you can use as well.

As for the hardware. I would get the bluetooth one. Quite convenient and useable on a smartphone with Torque or other APPs on iPhone or Android.

I have this one and it works amazingly well.
http://www.amazon.com/Bluetooth-Diagnostic-Scanner-Diagnostic--Check-Engine/dp/B0055AZ0A0/ref=sr_1_2?s=electronics&ie=UTF8&qid=1313104367&sr=1-2

I can't really help you decide weather or not to get a PCM4Less tune. Never really went that far in tuning my vehicle. I am just testing out different scan tools at the moment.
 

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2007 chevy trailblazer_ls
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130 Posts
Calling Roadie!

So I read most of this but started skipping to the end as I noticed the TSB was for pre-2007 vehicles and I only noticed one other 2007 owner complaining of this issue.

NOW, I know that in 2008 GM changed the type of fan clutches and it does not have a electrical connection.

I was thinking about getting the PCM4less ECM and fan mod, unless there is a similar solution for 2007 as it seems to be a neglected year in this situation regarding the reflash and the clutch. :D

Thanks!!!
 

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2004 chevy trailblazer_ls
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38 Posts
I have a 2004 Trailblazer with the same A/C issue at idle that many on this thread have. Hot days, when I stop, the compressor seems to kick off and warm air starts blowing out the vents. Once I start moving, all is well. One other thing that happens when I am stopped is the brake pedal will drop about an inch or so when the A/C cuts out. It happens almost every time the compressor seems to cut off. Anyone else notice this when their A/C cuts off when stopped?
I will look into the reprogramming of the PCM.
 

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2004 gmc
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26,181 Posts
And measure your vacuum for the power steering boost problem. Is your idle RPM staying constant when the compressor cycles?
 

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2004 chevy trailblazer_ls
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38 Posts
And measure your vacuum for the power steering boost problem. Is your idle RPM staying constant when the compressor cycles?
I have not notice the rpm's drop when it occurs.
I am not familiar with the power steering booster problem....
 

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2004 chevy trailblazer_ls
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7 Posts
I had the same trouble this past summer. I noticed a high pressure while checking the freon level in the system. This led me to replacing the fan clutch....Problem solved. I also did some research on fan clutches and went with the Hayden. When I opened the box it had a Behr mfg. sticker on it which is the same brand as the original I replaced.:tiphat
 

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2002 gmc envoy_slt
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10 Posts
My envoy had the same problem and I found out it was the fan clutch that was not spinning fast enough to cool the condensor at idle which raised the head pressure on the AC unit making the high pressure switch cycle off and on the AC compressor, thus not cooling properly. Installed new fan clutch and had the dealer flash update on the computer and problem was solved. Just a heads up I used a Dorman fan clutch and 2 years later the bearings started to make noise. Lucky my mechanic got me a new one under warranty. There is a thread on here about it.
 

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2003 chevy trailblazer_ls
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1 Posts
Lindenoil

All the vehicles I have encountered with R134 freon dont cool near as well at idle as when under way. It seems to be a characteristic of R134
 

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2004 isuzu ascender
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5 Posts
Poor/NO AC at idle

I wonder if adding an electric fan wouldn't solve this problem cheaper than replacing the OEM fan. The OEM seems to be another GM engineering marvel. The kind that has put them out of business twice now and will continue to plague them until they disappear all together.
 

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2002 olds bravada
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32 Posts
WOW: That was EZ

OK, I just completed the job in 45 minutes and I stopped many times to show my wife how to do it.

Notes:
1.) DO NOT waste your time (and fluid) removing the transmission lines. They simply pop out of the plastic clips on the shroud that hold them there (slide under the front to easily do this).
2.) The AC Delco fan clutch is $227 at Rock auto which is what the st(d)ealership would install (and charges $597). The AC Delco part is a Behr part which is made for AC Delco.
3.) The stealership charges 3 hours of labor to do the job where I, a novice did it in 45 minutes. All quotes from 3 different stealerships were over $800 ($300 labor + $600 part). Shame on them charging for 3 hours verses the 1 it really takes.
 

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2005 gmc envoy_denali_xl
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21 Posts
warm air

Mine has always done that, especially through the rear vents. If I am stopped for a long enough period of time, switching the font panel to "recirculate" and turning off the rear fan dial control seems to help. I always assumed it was hot outside air building up (we can smell the oil/exhaust coming through) and the hot roof warming up the ducts.
 

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2006 chevy trailblazer_ls_ext
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19 Posts
same ass damn problem. has anyone had a fix to it yet? if i get someone to run inside to get something for me, while i try to stay in the nice cool ac i get aggrivated until i start driving and it finally gets to its normal temperature!!!!! :hissy:
 

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2003 gmc envoy_slt
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9 Posts
I had the same problem and found out it was the blower motor relay witch also caused the fan to stay on after the engine was off and key removed for about 3-5 minutes.
 

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2002 chevy trailblazer_lt
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6 Posts
I have an 02 TrailBlazer LT. I've owned it for about 5 yrs. now. About 2 yrs. after I bought it I'd notice while driving down the road I could smell a musty smell from vents with A/C ON (smells like the old freezers you use to have to defrost when the ice caked up the inside...). Then one day I smelled the smell & my A/C stopped blowing cold air. I pulled ontot he shoulder to see if it would change back. I turned off my TB & sat there about a min. When I started it back up I had A/C working again with no smell. This went on all summer. The next summer when it started doing this hubby hooked up his freon gauges & level was fine. That summer I'd have to let it sit about 5 min. before it would come back on. Hubby had had enough of this by now so he jump-wired (unsure what it's really called) using a red & black wire to the battery (neg. & pos.) and ran it wherever & hooked me up a toggle switch to my hood release inside the cab. This switch turns the compressor on when flipped on & I have A/C....BUT it will freeze up & blow snow out of the vent LOL. I flip the toggle off and it thaws and will blow ice cld while thawing. When the ice cold stops I flip it back on and round & round we go with this process. Now this summer there have now been times when I turn on the toggle that the A/C never starts....hubby can reach in & turn the compressor thing by hand just a tad & when I turn the toggle back on it runs fine. Again, freon levels are fine according to gauges or both my hubby & a friends. he recently read somewhere there's a screen thing in the system that may be blocked & upon replacing it this issue could stop all together & run regularly. ((Sorry this is so long but don't wanna leave anything out)). HAS ANYONE MESSED WITH THE SCREEN THING??? Also, hubby has had that filter thing out that is under glovebox (a door held with one screw where an optional filter can go) & there's no filter in it. At this point we don't even put the lower panel back on under glovebox as we look under there often *LOL* We have also sprayed coil/evap cleaner up in there in the past to clean/flush it all out. OMG will this EVER end?!?!?!?!?!?! :confused:
 
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