What did you do to your GMT today? [Part II]

BrianF

Member
Jul 24, 2013
1,294
West central Sask.
Got the Trailblazer back from the shop. AC system held pressure but they added dye anyways in case of a slow leak. They recharged it and she blows cold..... very cold, uncomfortable in fact. I had jumped the low pressure switch previous and compressor did not kick on, so I figured worse. Oh well.

They found the same things as myself on the ABS module issue. Power to the unit, good ground, battery tested good. Either the ignition switch (unlikely as it was swapped when the problem first popped up) or the module itself is bad.
 

flyboy2610

Member
Aug 24, 2021
596
Lincoln, Ne.
Gave the wife's '06 TB the same treatment I gave my '04 TB EXT: new brake pads front and rear, oil change, cleaned the throttle body, did the re-learn.
While I was doing the left front discovered that the CV axle boot was ripped up. Have 2 new axles coming now. While I'm in there changing the axle I'm going to go ahead and replace the left outer differential seal and bearing. I replaced those on my '04 last December, so I know what to expect. The parts aren't too expensive and I don't want to have to get back in there to do it later.
She's going to be going up to her mom's in northern Nebraska in 2 weeks for Memorial Day and I don't think I'll get to it before then. I may just cut the axle in half and pull the halves out, leaving the stubs in the diff and hub. That way I know it won't fail while she's out on the highway.
 

Zaab

Member
Apr 30, 2025
32
Ohio
Gave the wife's '06 TB the same treatment I gave my '04 TB EXT: new brake pads front and rear, oil change, cleaned the throttle body, did the re-learn.
While I was doing the left front discovered that the CV axle boot was ripped up. Have 2 new axles coming now. While I'm in there changing the axle I'm going to go ahead and replace the left outer differential seal and bearing. I replaced those on my '04 last December, so I know what to expect. The parts aren't too expensive and I don't want to have to get back in there to do it later.
She's going to be going up to her mom's in northern Nebraska in 2 weeks for Memorial Day and I don't think I'll get to it before then. I may just cut the axle in half and pull the halves out, leaving the stubs in the diff and hub. That way I know it won't fail while she's out on the highway.
May I ask if you do ecu relearn by scan tool or by disconnecting battery? Do I have to do the relearn after cleaning throttle body?
 

flyboy2610

Member
Aug 24, 2021
596
Lincoln, Ne.
May I ask if you do ecu relearn by scan tool or by disconnecting battery? Do I have to do the relearn after cleaning throttle body?
The relearn is done to get rid of the small adjustments that the computer makes to compensate for a dirty throttle body.
Before cleaning the throttle body, remove the PCM1 and PCMB fuses from the underhood fuse box. On our '06 and '04 TB's they are fuses 10 and 28. Leave them out for 30-45 minutes and the computer will forget the adjustments it's been accumulating.
After the throttle body has been cleaned and the fuses reinstalled turn the key to the run position but do not start the engine. Leave the key on for 2 minutes, then turn the key off for 1 minute. After 1 minute start the engine but do not depress the gas pedal. Let the engine do nothing but idle for 10 minutes, don't depress the gas pedal during this time. After 10 minutes I always turn the key off for 1 minute, then start the engine and go for a test drive.
Easy-peasy mac-n-cheesy! :2thumbsup:
 
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BrianF

Member
Jul 24, 2013
1,294
West central Sask.
Figured out the fan problem on the Trailblazer. Back in the winter it had some intermittent problems where it worked and didn't work. Then after getting the ac working, it failed completely. You could hear the relay or whatever it is clicking with movement of the fan switch.

I dug in and had no burnt connectors at the resister pack. I had power at the resister and at the fan connector. Then I found it. The damn connector at the fan jiggled around more than me trying to run. I used some thin plastic to shim the connector and now it works again.
 

dhanger

Member
Apr 8, 2025
9
Arizona
Compression test and leakdown test.
2004 TB LS I6 engine.
Compression 180-190
Leak test 76-86%, mostly heard from oil filler cap with a little from intake and exhaust so mostly rings I guess.
I don't know but that seems pretty decent for 191k miles. Would a top end soak help to improve the rings with this many miles?
 

flyboy2610

Member
Aug 24, 2021
596
Lincoln, Ne.
Time and weather finally cooperated long enough for me to change out the CV axle, differential seal, and bearing on the drivers side of the wife's '06 TB. The upper ball joint wasn't looking too great so I replaced that also. I didn't charge her any extra for that! :smile:
I'm glad I started on it early this morning because we're having a rain/hail shower right now.
 

Mooseman

Original poster
Moderator
Dec 4, 2011
26,550
Ottawa, ON
Yesterday I finished work early and decided to tackle the malfunctioning actuator for the defrost as it was stuck on defrost. I had tried to do a relearn in the past, which seemed to fix it, but it got stuck again. I got a new CCC actuator from scAmazon (yeah, yeah, I know :frown: ) and took apart the lower dash. Getting in there was a bitch as I'm not as flexible as I used to be (not that I was very flexible to be begin with :laugh: ). So get the actuator out, open it up and it looked fine, no broken gears or anything. Put in the chinesium actuator, do the relearn via the Tech2. Went through it but it was still on defrost. Huh? Thought maybe it's the other actuator, the one with the gear. Pull it out and confirm that it's for the floor and vents. Put it back in and now the vents don't work :mad: . Pull it out again (by now the screws practically come out by themselves) and the actuator is all the way to one end. Maybe I didn't put it in right and it jumped the gears. Open it up and the "timing" was off as per this post. Back together, relearn and the vents are now working. Back to the defrost, open up the old actuator and it's timing is also off. Set the gears right, slap it in, another relearn and it works.
Opened up the CCC actuator and I can't make heads or tails of which way the gear with the dots should be as it's different than the OEM one. I might return it but it was just $25 and not worth the trouble. Then again, I might win the Amazon lottery and be told to keep it even with the refund.
 

littleblazer

Member
Jul 6, 2014
9,270
Changing a lightbulb. Think I did something wrong.
20250531_214746.jpg20250531_214850.jpg
 

TJBaker57

Lifetime VIP Donor
Member
Aug 16, 2015
3,444
Colorado
Open it up and the "timing" was off as per this post. Back together, relearn and the vents are now working. Back to the defrost, open up the old actuator and it's timing is also off.


I have seen small cracks develop on the large 'final drive' gear right down where the plastic gear is splined to the drive hub. This loosens the 'grip' and the plastic gear can then rotate on the hub when under enough strain as happens during a relearn. Once it has slipped the plastic splines are compromised and lose their grip.

I have seen new actuator designs that eliminate the separate position potentiometer and I think they built that function into the final drive gear?

IMG_20190320_105943.jpg
 

Mooseman

Original poster
Moderator
Dec 4, 2011
26,550
Ottawa, ON
I have seen small cracks develop on the large 'final drive' gear right down where the plastic gear is splined to the drive hub. This loosens the 'grip' and the plastic gear can then rotate on the hub when under enough strain as happens during a relearn. Once it has slipped the plastic splines are compromised and lose their grip.
I checked for cracks on all the gears and they were fine so :confused: . I think maybe on a -30c morning, it was probably all stiff and jumped a tooth.

I have seen new actuator designs that eliminate the separate position potentiometer and I think they built that function into the final drive gear?
Mine has the pot gear. Its gear is just different with the numbers and the half moon missing, which helps me with the orientation of the dots. Maybe the one you got they were substituting the actuator for recirc which doesn't have it?
 
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TJBaker57

Lifetime VIP Donor
Member
Aug 16, 2015
3,444
Colorado
Mine has the pot gear. Its gear is just different with the numbers and the half moon missing, which helps me with the orientation of the dots. Maybe the one you got they were substituting the actuator for recirc which doesn't have it?


I pulled this new spare from my shelves....

Looks like they built the positional sensing right into the final drive?? Next to the bright copper arc is a black resistive strip.


20250602_094609.jpg20250602_094544.jpg20250602_094122.jpg20250602_094252.jpg
 

Mooseman

Original poster
Moderator
Dec 4, 2011
26,550
Ottawa, ON
Oh , maybe that's the 2002 only version. Would explain why it's 2002 specific.
 
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Zaab

Member
Apr 30, 2025
32
Ohio
Changing air filter for the first time on GMT360. To my surprise the dealer has put a pre-oiled STP paper filter in it. Swap with new Fram Ultra. Of course loss the bottom left screw despite me trying my best.
Another round of power steering fluid change. Empty the reservoir and put new clean fluid in. It's getting better.
 

Zaab

Member
Apr 30, 2025
32
Ohio
More interesting work!
So I notice my vehicle always in night mode. Low beam on all the time. Dim DIC with dash light on all the time. And the ambient light sensor is absent.
1749343625501.jpeg
It's very easy to get the trim pieces off. Use anything with a flat head to pry open both A pillar cover hatches, unscrew the philip screw inside, take off the pillar cover then popping out the clip for the front trim piece. To my surprise, when I'm searching for the ambient light sensor wire, I feel the sensor still attached on it. Not sure why the last guy work here hides it. Maybe he's in a hurry and just do minimum to get the car on the road?
1749343766127.jpeg
It's not very pleasant to get the sensor on, mainly because working in limited space, and I just trimmed my nail so couldn't disconnect the sensor first and put it in. But I managed to get it in place after some struggle. Vola! Now my auto headlight works, and I can finally read my DIC under the sun.
1749343951368.jpeg1749344381301.png
1749344489598.png
Wondering why the GM one has a blacked-out dome and mine is clear? Anyway, I saved ~$40 so not going to complaint.

PS: this poor guy get stuck on the A pillar for who knows how long... And when I took down the pillar cover, a LIVE dragon fly flew out (???
1749344580627.png
 

Mooseman

Original poster
Moderator
Dec 4, 2011
26,550
Ottawa, ON
It could have been pushed in accidentally while cleaning the dash or maybe rubbing it "real good" and oops. Or maybe just forgot to put it back in after some work. Anyway, you got it done right.
 
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