Need some ECM help 2006 TB 4.2 AT

Vaughn M. Elliott II

Original poster
Member
Aug 27, 2016
16
Murphy NC 28906
I made the mistake of taking my Trailblazer to the the local GM dealership to get the driver side door harness fixed.

Got home ok, went to start it next day, no love.

Checked battery, checked everything I knew of, then thought- hey, had a Jeep once where the shifter cable was beeped up.

So I got under it, forced the shifter lever into park, and it cranked, but check engine and every other light was on.

I hooked up my OBD-II and over 100 codes pulled.

I took it to the one decent GM mechanic(I had thought he still worked at the dealership) and he said that the shifter cable was bad, the ECM/PCM is basically just a ground but it is bad, and on the J2 middle pig tail there is a grey "lever" that flips down and locks the pigtail onto the J2, he says j1 j2 and j3 all have ends that lock on using that flip down mechanism. They had forced J2 into the locked position using a screwdriver or something similar.

He said that the under of the Trailblazer had grass stuck every where, that the shifter cable had grass stuck in it, etc. He also said he found a printed VIN tag on the ECM itself and it was from a Colorado. He said it is not correctly programmed to my Trailblazer, that's why there is a blue million codes, and he no longer had access to a tech 2 to fix it. He said if I could get the ECM/PCM software for a 2006 Trailblazer and a Tech 2, and trick the Tech2 into thinking it was plugged into GM's network- I could fix it. He would not attempt it, and no one else I can find will attempt it. I live in BFE's BFE.

The GM dealership called me and their former mechanic a liar, said TY,FY,GB.

So I need the pigtail that locks onto J2 with the flip down lock, or I need the lock.

I have a Ching-chong special complete GM Tech 2 with software that is supposed to be here Friday.

But he said I needed to fix the lock on the J2 pigtail before I tried to fix anything else, as the ECM/PCM is just a ground. What it is the name of that flip down lock ? Can I buy it off Ebay or is it a salvage yard only item where I will need to buy the pigtail and the flip down lock ?

Thank you all.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
So how would it have a different PCM if you brought it in for door harness work? Or is there other info you ate omitting? Swap or something?

Anyway, the Tech 2 you are getting will be able to program the PCM with the included Tis2000 which us good up to 2009. You'll need a laptop with XP to install it, preferably with a serial port. Check my thread in the Tech 2 section.
 
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Vaughn M. Elliott II

Original poster
Member
Aug 27, 2016
16
Murphy NC 28906
So how would it have a different PCM if you brought it in for door harness work? Or is there other info you ate omitting? Swap or something?

Anyway, the Tech 2 you are getting will be able to program the PCM with the included Tis2000 which us good up to 2009. You'll need a laptop with XP to install it, preferably with a serial port. Check my thread in the Tech 2 section.

Nothing left out. I got my Trailblazer back eff'd up.

Tracking says tomorrow for Tech 2. I got out a Touchpad with a serial port emulator and installed Win XP.

Still have to find that flip down lock to ensure to everything works.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
That is still an effed up deal if they messed with the PCM, especially if it was fine going in and screwed up coming out. Those connectors don't tend to just break like that. Somebody screwed up somewhere. Or just one weird coincidence that it rolled out of the dealer fine and the PCM dies later, which then the connector breaks taking it off. The Colorado VIN could have been from a replacement in the past?

So much strange crap going on, it's worth it to go into it yourself with the Tech 2. It will pay for itself in no time.

BTW, check this thread for instruction on installing Tis2000 and avoiding having to use a dongle.
Computer and Tis2000 setup for Tech2
 
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Vaughn M. Elliott II

Original poster
Member
Aug 27, 2016
16
Murphy NC 28906
Dear Mr. Mooseman: Thanks for all your help.
I lied I left something out.
The night I went to pick it up, the dealership had closed but they had put the TB where I could get it. When I started it it the check engine came on it, but I went on home. That is where I seriously effed up.

This dealership- JJ- is the only GM dealer in an 80 mile radius in Western NC. I found out from talking to one of their competitor dealership's parts manager who once worked for JJ- that they get in a vehicle for a warranty repair(mine was in for a warranty repair) and they use that warranty repair vehicle to beat on sell one on the lot. It is not uncommon for them to take off the state issue vehicle tag and put a dealer tag on it and drive them home.

It was not a coincidence. And it sure looks like I am screwed because I can't find a parts manual online, and I went to the local Pick-&-Pull and they had a 2005 4.2 LT in the same color as mine even and the ECM connector uses a 5/16 or 1/2 bolt to hold the ECM connector on. They were going to give me the ECM connector because one of their boys has an '08 Duramax and they messed with his ECM, and they felt bad.

The transmission cable on mine worked fine in park and pulled back into gear but would not return to park unless you got under it and forced it forward.

This afternoon I found a pretty bad dent on the passenger side fender when I washed and clay barred it. They had tried to knock it out.

I went by this morning and the service manager would not look me in the eye and just asked me to leave after I told him my story(I did not mention the year, color, or specs- just said Trailblazers) and showed him some pictures of the engine compartment. One kid working there on a Buick Ranier noticeably quit what he was doing and just disappeared- no one else did. When I asked one final time about the connector, the service manager got red faced, raised his voice, and said "That 2006 is a 12 year old vehicle, sh*t goes bad on 12 year beaters all the time". He knew me, the vehicle, the year, and the specs the moment I walked in the door and this has been over a week ago now- kinda odd there. My 2006 was my favorite vehicle and had 54k original documented miles on it, including matching Carfax miles, DMV miles, and I was the only owner.

I'm pretty upset right now and I figure I am screwed. If I hadn't listened to my wife's bitching about GM's Recall Notices none of this would have happened.

If the car gods are looking out for qI am going to fix it right, get the fender replaced and continue sporadic driving. Including the weekly 15mi Sunday drive.

I will read up on the Tech2 and Dongle. No doubt I will need help there.ggb
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
It's incredible that this sort of thing still happens. You almost have to take pictures and document your vehicle before and after the service, especially the odometer.

I'm getting my Caprice serviced on recalls soon. Given the rarity and performance of this vehicle, I will take pictures. Almost feel like staying there with it to watch them like a hawk.

I hate dealers.
 
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