2007 Engine PCM Harness Compatibility

cornchip

Original poster
Member
Jan 6, 2013
637
With these trucks in the pic'n'pull yards, I am wondering if I can pull a complete 2007 Engine PCM harness at my local yard. My reasoning for this is mostly for my own convenience as it's hard to trouble shoot the vehicle you drive on a daily basis when it comes to the lousy wiring they all have. My question is, how compatible pin for pin do you think a 2007 compared to another 2007 really is. If so, I could pull and inspect/repair off the truck much easier than on. I have had multiple codes and a no start all related to breaking wires.
 

Matt

Member
Dec 2, 2011
4,019
What do you mean by compatible? They should be identical regardless of whether it was a TB, Envoy, Old or whatever make they were building on the same line.
 

Matt

Member
Dec 2, 2011
4,019
2007 to 2007 should be identical.
 

Shaw520

Member
Sep 20, 2017
289
Northeast
When mice rendered my 05' disable,.... I purchased another 05' engine harness from ebay,... it was identical and surprising easy to install (basically plug and play),.. AND cured all codes and disabling issues.
You can find that thread in this forum.
 
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cornchip

Original poster
Member
Jan 6, 2013
637
This is something I need to do before March when I emission test (Ontario Drive Clean). The two codes I have are instantly on, one of those is a repeat code I had fixed at a garage....so I know it's broken again. Add to this a harness repair that caused a 'no' start....lost a day's pay along with a rental car. So that's at least three sketchy wires in the bundle that should be re-pinned. I'm going for it. I need a proven second harness that doesn't code....then maybe I can then fix the first one. I'll post my results when I have them.

Thanks.
 

mrrsm

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If eBay does not have the exact 2007 you seek, these are also available (... hopefully with some that have not been manhandled too much with a Junk Yard PayLoader). The first one on this list comes with a Warranty; but all three offers here are at a Premium Dollar Price that really won't seem so high as March and the Inspection Day 'looms' closer on the horizon:

https://www.partrequest.com/parts/2007/chevrolet/trailblazer/engine-wiring-harness
 
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cornchip

Original poster
Member
Jan 6, 2013
637
I called the dealer to verify my VIN to get a correct part number. There are variants close to year change 2006. My parts number for the harness is 25821217 (2007 4.2/auto 4x4 LT) and verified by the dealer. I asked what they wanted (892.00 Canadian...ouch!). A used one shipped from Nordstroms at 250 US with 60 shipping is going to roll in at just over 420 CAD plus other taxes. That used harness might have been shown little love during removal and has a real possibility of having similar issues. The good news, I have found a NEW GM harness over the phone local complete for 600 CAD (480 US). Looks like the way to go.

Here in Ontario I can get by just ONCE with a failed test under the new rules as of April 1st 2017. Under those rules, a repair cap done at an accredited garage of 460 dollars (you don't get much at a garage for this money) must be met to drive for two additional years. Consecutive conditional passes while failing are prohibited. Long story short, I need to pass this time around...maybe fail two years from now and pass conditionally then and drive two more. At that point I'll be into another truck with the mileage I'll have then.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
It's all a conspiracy to get us to buy new vehicles every 7 years.
 
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Sparky

Member
Dec 4, 2011
12,927
Most vehicles should be able to pass even at 10 years old. My old 02 Trailblazer was fine at 14 years old except for a failing clutch fan which could have been easily remedied if it had been worth doing.

I still miss that truck sometimes.
 

cornchip

Original poster
Member
Jan 6, 2013
637
It's all a conspiracy to get us to buy new vehicles every 7 years.

For sure. Thinking you can somehow buy a premium item to lower it's cost of ownership over the long haul isn't happening these days. Slapping a Honda or Toyota badge on it won't save you either. It's the times we live in.
 

cornchip

Original poster
Member
Jan 6, 2013
637
Well, it's done. Harness showed up today (GMPARTSDEPOT.CA aka Jim Tubman Chevrolet in Ottawa). Just need a warmer weekend in the next month or so to swap it out. Fingers crossed it doesn't open up a can of worms and that it fixes the butchered repair I had done to cure a 'no start' issue I had.

y4mFw5re8cQBEPQoc8GMljrvrHYm9eO5vetba5NSZSAodbOVlBAbZWWdf7a6Vuu1nxUn9BMZB2mW6G1-Sbwb2E_Bx5C9R6wmnXLCGo5TFmvc3rJbqM6ACFUuIPeWSmleu0ZcCfxYMLslHCy7ggZC8IfdvUGcw-L5Wlr_h0pFL0FVsyLkQeTfgsqk5vDF6rEr0eazT1OO2qTTAQEldCae26AVg
 
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Mooseman

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Dec 4, 2011
25,257
Ottawa, ON

Shaw520

Member
Sep 20, 2017
289
Northeast
That harness looks brand new,....do you mind saying how much you paid ?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Yeah, and probably $20 at Kenny U-Pull. But then, you know it's good.
 

cornchip

Original poster
Member
Jan 6, 2013
637
Yeah, and probably $20 at Kenny U-Pull. But then, you know it's good.

We have a Kenny U-Pull in Hamilton that had a 2007 in yard back in September. I just couldn't bring myself around to remove it. I snoozed on that one. :sleepy:

I've paid for 2 separate repairs at a local garage, the last time making it impossible to emission test when I got it back (CEL on). That last time it went in behind a CAA tow truck. I missed 1 day of work and rented a Chev Traverse to make it in to work the second day. It was an expensive two days, and I beat on the Traverse which made me feel lucky to have a Trailblazer. That 3.6 revs real hard.....it's all granny and pants on fire.

That last repair by the way was for a no start. The symptoms after key in were messed up shift indicator lights (all lit) and no crank. I automatically thought about the usual ignition switch mentioned constantly in the forums. I did try to jumper the starter relay just to hear it crank.....but after that, who knows. During the repair, I was told it was the PCM and a new one was being programmed at the closest Chev dealer (another tow from the small shop to that location). The dealer called them back to say it wasn't a PCM at all and another return tow. Further diagnosis revealed a power feed in the harness was close to being broken, but had a strand or two left. What was described to me was something like this, you can check it for continuity, and that's usually fine.....but when the PCM pulls more AMP's than the wire can support it can't supply enough voltage to the load. This garage used an old trick by wiring a 6054 Halogen and checking the voltage drop compared to a healthy strand of wire. They repaired the broken section and I got the truck back, happy to see it start again.

New problems after that, a CEL for the purge nent valve (I fixed that myself using a diagram from Trailvoy showing the PCM pin assignments....something like pin 25 on the center connector). The other new CEL is for a 1-2 shift solenoid from the generic P code I pulled. It's instantly on with the key....so it's failing a diagnosis check at start and is likely another broken PCM ground to the solenoid. Could be a solenoid after that as well. I'd need to have a Tech 2 in hand to cycle the solenoid to verify it. Add to it, I don't have a pin assignment for the 1-2 solenoid on that plug. I'd have to run a continuity check on every wire till I could isolate the wire. All that is just a metric ton of no fun it this weather. I went new and will roll the dice from there. It may need to go in again, at least this time it shouldn't be a wiring issue having spent the money the correct way. Fricken shame the government couldn't take my parts bill towards the conditional pass....but it has to be done at an accredited repair facility to count. Spend spend spend.....keeps happening and I'm getting a 4Runner. Not crazy about them., but I can't do CUV. Jeep has the 4 door Wrangler still which offers the drive train layout I like while being a Chrysler product which I hate. Besides that, I'm slowly restoring a 87' YJ Wrangler and putting a 2008 Vortec 4200 into that. Don't need two Jeeps.

It's getting late and I'm getting tired so nuff said. Later...
 

Shaw520

Member
Sep 20, 2017
289
Northeast
Bought my 05 used harness on eBay,... w money back guarantee for 100 US.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
As you're taking the harness apart, check the fuse box. Some have had burnt or corroded connectors. Some have melted down. Not a lot of that but has happened.

Whereabouts are you? I have a Tech 2 in Ottawa (today in Lindsay moving my son to college).
 

cornchip

Original poster
Member
Jan 6, 2013
637
As you're taking the harness apart, check the fuse box. Some have had burnt or corroded connectors. Some have melted down. Not a lot of that but has happened.

That would be a major disappointment. The garage didn't mention anything about it, but they only answered questions I asked. Best to keep the customers from getting to educated.

Whereabouts are you? I have a Tech 2 in Ottawa (today in Lindsay moving my son to college).

A good offer, but I can't see that happening today. I'd love to do a hands on with the Tech 2 to further my understanding. I still might buy one, not just for the Trailblazer....but for the Jeep with the 2008 4200 swap. I have the PCM and harness for it and could get some long term use from the Tech 2 if I owned one long after the Trailblazer is gone.

y4m_7_1BNDLaucwphWipXt4mSc5XRaCVUfKhjjXQwpyax6q5HV9Dv5BnzqLfODNEjbuKEc-FlkkUw1W6o8180qiU_wTIYQU_Nh5e6vTlBjNvnsLhMtpFTpxxYvilY_ES-RixZ3TFaqzPRwyN4_rV-dXFDzKPcIsDPXSq-40wrfSu3zynAnJhmfLAmb1uV8a7P8LergAjCrDSi2N2tcl5OH6Cw
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
He is swapping in a Vortec 4.2L into that Jeep. :biggrin:
 
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Shaw520

Member
Sep 20, 2017
289
Northeast
Looks like a fun project cornchip,..did you start with a 2wd tb, or swap the pan, curious as to what tranny/TC combo worked for ya.?..is that an NV1500 5 speed manual I see there?
 
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cornchip

Original poster
Member
Jan 6, 2013
637
Looks like a fun project cornchip,..did you start with a 2wd tb, or swap the pan, curious as to what tranny/TC combo worked for ya.?..is that an NV1500 5 speed manual I see there?

No advantage to a 2wd 4200 from what I gather....the pans are likely identical. Modifying or the fabrication of a new one is about the only way around that.The transmission is a Colorado/Canyon AR5 from a 2010 mixed with the rear half of A Jeep AX15. The output is retained and a spacer is added to the rear extension and the original Jeep NP321J is in the rear with a NP241C 27 spline input gear.
 

cornchip

Original poster
Member
Jan 6, 2013
637
Cornchip, do you have a physical failures pinpointed? I would be interested so I can check when I'm doing my conversion harnesses.

I'll update you when I get that far and take a picture.
 

Shaw520

Member
Sep 20, 2017
289
Northeast
No advantage to a 2wd 4200 from what I gather....the pans are likely identical. Modifying or the fabrication of a new one is about the only way around
My thoughts were toward the oil pan on the 4wd would have the t/c opening/pass-through, whereas the 2wd would be sealed,.. No?
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
They all have the same pan
 

Shaw520

Member
Sep 20, 2017
289
Northeast
I see,..so does the 2wd version have a plate where t/c disconnect would go ?
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Nope, just a hole thru the pan.
 
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cornchip

Original poster
Member
Jan 6, 2013
637
Been busy preparing for my emission test. Started to change out the harness, and have put it off till warmer weather. It's gonna be a bugger. Anyways, I've twice been under the hood chasing wires. As mentioned, I repaired one myself and it's holding together. The garage that fixed my no start made repairs to two wires on plug C2. Ones a heavy gauge wire (the original cause of the no start) and the other is a mystery wire. Only a proper 2007 shop manual diagram would tell me that. On C3 I wnet looking for the P0449 (Tech 2 error 'open') issue and found a broken power feed wire to the vent solenoid. Fixed that and still it failed (different message however on the Tech 2...'shorted'). I found it confusing and sprung for a new vent solenoid. Bingo!. All done except I may have a more serious issue with P0894 transmission component slipping. Happens after 15 minutes on the highway. The heat build up must be causing a leak and slipping the TCC. Usual suspects I'd imagine....the stator bushing or other?. So with a code up (internal) and the tests ran (no MIL lamp) I'd say I should be good to go at least for that part. Anybody here ever been in a similar situation. Rules here are foggy in Ontario.

y4mh8PqPBOlvgU2NfHYtAOgMTejUNSq7eI-1mp0CxWtHgpX_OUfQhDmrXfMdEevuoqhKkt_H9IS744mtU5HbBCovMEcGQjBixJo8stjGR1dQJabvxQ6bZAJqbiJwrZHSt2DHbqpccuTuA1C23aU3nHqaF_JS2bIIat8d7JvY-CaCOPZsjk9S4zDgxfKEtqK9nQor2ddOFmIV1UNEBg5DxygfA
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
The slipping TCC is usually caused by a worn valve in the valve body. A shift kit usually fixes that.
 

cornchip

Original poster
Member
Jan 6, 2013
637
Aside from from a repaired valve body, how about a good cooler?. Problem is heat related. My normal drive into work is 25 minutes of 80km speeds. I get no code during that time frame. Highway speeds bring on the code, yet I see and feel nothing to tip me off feel wise. The cooling must be just inadequate to begin with. Maybe a bit of work to the transmission and a proper plate style cooler will buy me some time....a little lipstick for the pig.
 

Sparky

Member
Dec 4, 2011
12,927
When the bore gets worn enough, a warmed up transmission will trigger problems. Been there done that. My old car would be fine in the winter mostly, but come summer it would start slipping out of lockup. Hotter it was outside, the faster it would act up and usually would end up failing to lock at all. When I finally tracked down what was going on and fixed the valve body it never acted up again. Never bothered with a trans cooler.

That said, it isn't a bad idea to get a cooler, at all.
 
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Shaw520

Member
Sep 20, 2017
289
Northeast
I realize its freezing and NO ONE want to get out there in this stuff,...but generally speaking the harness swap wasnt as bad as Id thought ( I did mine in warmer weather of course),... its basically plug and play with all the leads being self explanatory. The toughest one was the the big oval plug on the tranny, a mirror was helpful to get the proper orientation.
 

cornchip

Original poster
Member
Jan 6, 2013
637
Past emissions today and good to go. Other things I'll deal with in time when I'm better prepared. Weather and more day light is going to help.
 

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