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The code points to an electrical fault with the rear locker's magnetic coil, or the harness going to it.

WTF is up with this thing all of a sudden? I tried to take it out for a quick errand, and had to turn around before I got out of the neighborhood. I had a stability control failure message come on, and it's got a noticeable jerk on the 1>2 shift.

I thought I was just starting to get back on good terms with this stupid truck.

Dude...

Abs sensor?


Coop

I put the scan tool back on it this afternoon. There's a ton of data bus errors. I'm going to need to take a good look under the truck and see if I messed up any wiring harnesses when I was doing the exhaust. The transfer case actuator is the only one that I know is nearby. If there's a short somewhere, that could explain everything.

That turned out pretty good. As long as it doesn't leak i would run with it.

Well I'm fucking stumped. I pulled it in the garage and everything is fine. All the codes are history codes now, and the transfer case and both lockers work fine. Everything under the truck looks fine too.

The only thing I've got is what seems to be a minor kink in the wiring for my UltraGauge. It's pretty thin gauge crap, and I know the Chevy dealer had to unplug it in order to hook up their scan tools. It would also explain how both the Class 2 bus AND the high speed CAN bus were showing errors, since it's the only thing besides the ECM that's hooked hooked up to both. Vibration irritating a shorted wire would also explain why it took a couple days to show up.

I'm going to leave it unplugged and take it for a drive tomorrow after work. It's a fucking long shot, but it's all I've got right now.

Jeff V. wrote: ↑Wed Nov 22, 2023 1:56 am Well I'm fucking stumped. I pulled it in the garage and everything is fine. All the codes are history codes now, and the transfer case and both lockers work fine. Everything under the truck looks fine too.

The only thing I've got is what seems to be a minor kink in the wiring for my UltraGauge. It's pretty thin gauge crap, and I know the Chevy dealer had to unplug it in order to hook up their scan tools. It would also explain how both the Class 2 bus AND the high speed CAN bus were showing errors, since it's the only thing besides the ECM that's hooked hooked up to both. Vibration irritating a shorted wire would also explain why it took a couple days to show up.

I'm going to leave it unplugged and take it for a drive tomorrow after work. It's a fucking long shot, but it's all I've got right now.

This seems plausible to me. Hopefully it works.

Took it for a short drive tonight. Service 4WD light came back on, but it was otherwise normal. I'll troubleshoot the locker circuit at some point. Might also pick up a spare transfer case (and diff) control module in the meantime. That was at least shared with other GM trucks.

Me wrote:Might also pick up a spare transfer case (and diff) control module in the meantime. That was at least shared with other GM trucks.

24250771. Fits: H3 (Discontinued)

Fuck you GM. Fuck you.

Jeff V. wrote: ↑Fri Nov 24, 2023 2:42 am

Me wrote:Might also pick up a spare transfer case (and diff) control module in the meantime. That was at least shared with other GM trucks.

24250771. Fits: H3 (Discontinued)

Fuck you GM. Fuck you.

Ugh so annoying!

Jeff V. wrote: ↑Mon Nov 13, 2023 7:57 pm Your truck isn't half rusty with faded trim and sporting an exhaust you just built out of scraps.

Coming from someone who has worked in the best exhaust shop in my area for 8 years.... That is easily the best home job exhaust repair I've ever seen. I would like to see a little more penetration on the welds (looks like you're using .030 wire and have the voltage down a bit) but the fitup is really good. For future reference a 3" muffler with a piece of 13ga wall 3" exhaust tubing in the ends fits perfectly over gm 2.75" OEM tubing.

Wow. I really appreciate that. Thanks!

I just set the voltage and wire speed to what the sticker on the welder suggested. More than anything else, I need practice.

Yesterday I finally stopped putting this off, and pulled the cover off the rear diff. The locker failure is obvious, but I'm totally dumbfounded at how it happened.

Something pulled the locker cable grommet down inside the housing, and cut one of the wires.





That "something" was the wreckage of the bracket that keeps the locker coil from rotating. WTF.



This is what it should look like.







If you go to this video at 18:30 and 55:30 you can see where it goes. https://www.youtube.com/watch?app=desktop&v=v4XyV2qIRew

When I pulled the cover off, the bracket was wedged between the diff and the cover. If this thing had gotten into the gears, it could have been very, very bad.

So how the hell did it happen? It's bolted to the bearing carrier on the left side. Nothing that moves should have ever gotten close enough to rip a 1/8" thick steel bracket off its mount. The carrier bolts are still right, and the loops that hold the bracket are still in place under the bolts. The only signs of a problem were some seepage on the top of the diff due to the plug being pulled in, and the error code for the locker. It was totally normal otherwise.

That's really an odd failure

Weird

It knew what was coming.


Coop

Could have been a slight defect in manufacturing that was unnoticed and caused one of the loops to fail. Then the other failed when it moved around

It's so weird. I'll probably never know exactly what happened. On the bright side, I think I can fix it. The bracket itself is a pretty simple shape. I'm hopeful I can flatten out what I have left and use that to make a new one. Of course the GM part is discontinued, and it was only ever used on locker equipped H3s, like every other special little snowflake part on this damn truck.

As far as the coil wire goes, I'm hoping I can install an inline crimp and some oil resistant shrink tubing.

Probably built on a Friday.

I think Coop must have been sending bad vibes your way.