SOLVED - Big 3 upgrade, EVERY warning light on immediately after.

[George B]

Before I loaded the parts cannon full of modules I would look for somone with a tech2 and dig into troubleshooting the CANbus.

 

[iamdub]

Are these systems extremely sensitive to voltage changes? The only other impact I can think of is that the voltage seems to be more consistent on long drives. Prior to the wire job, it was ~14 on the gauge and it sits at a steady 14.5 while driving now. Actually measures out to 14.2-14.7 with a voltmeter.

With these rigs having RVC, the components should be perfectly fine experiencing 12-14.xx volts.

 

[iamdub]

Some of my exterior lights (previous owner ran overheard lights on the roof) do stay illuminated for long after I pull the key and close the doors. I do also keep a dash cam hardwired in the vehicle, I may have left that plugged into 12v power when I pulled the battery...

Modules go into "sleep" and "awake" modes. I'm wondering if the camera, presenting a slight draw, was keeping a module (BCM?) active/awake.

I'm wondering if a module just had a rude awakening when the power was restored with extra equipment, such as your camera, was connected to it. Maybe disconnect anything aftermarket like that (lights can stay as long as their switch is off), let it sit for a while in hopes to put the modules to sleep then disconnect the negative battery cable. Let it sit for awhile then reconnect the battery cable. Test from there.

 

[Tyrant]

Thank you guys for sticking this out with me; I commute 170 miles from home, so I've been gone this past week. I'll be home tomorrow, so I'll find a local shop with a Tech 2 or bite the bullet and order one.

After blowing the dust out of the various connectors and slathering them with dielectric grease yesterday, the CEL disappeared on me. It's still throwing a U0109 code, despite clearing it twice, but it revs hard to redline now in both 2 high and 4 high, and shifts through all of the gears again.

That cut one issue, thankfully. I still don't understand why I would have 4 high and not 4 low, but the U0102 is really stumping me. I didn't have 4wd issues before, but I have used both of these scantools with the vehicle in the past and they never popped that code previously.

 

[BG1988]

Wait a moment - do you mean there are two of the smaller wire that runs forward from the ground? I had one 4 awg wire and one approx. 10 awg wire, I connected both to the negative side of the battery. Is there supposed to be a third? That would explain a great deal, if so!

yeah a ground wire from the battery to the chassis (under the radiator) this wire is connected still ?

 

[George B]

Wait a moment - do you mean there are two of the smaller wire that runs forward from the ground? I had one 4 awg wire and one approx. 10 awg wire, I connected both to the negative side of the battery. Is there supposed to be a third? That would explain a great deal, if so!

There are two grounds landed on the frame under the core support. one comes from the negative battery terminal and the other comes from elsewhere. I believe the fans are included in the second one.

 

[HACK BLOCK]

my brother had the U0102 code after getting some work done and in his case it was a grounding issue. he had returned his tahoe to the shop that did the original work and they were able to fix it

 

[Tyrant]

I snapped up a Tech2 and I'll be trying to diagnose the canbus issue directly; I pulled the secondary ground behind the bumper just to be safe, wire brushed it and re-attached it. I also replaced every J case fuse and every mini blade fuse in the UBEC with new Littelfuse replacements just to be safe. I have a pile of extras now, too, and I cleaned the dust off with compressed air.

The engine seems to go into limp mode every other drive, refusing to rev beyond 2K in drive or accelerate hard... The next time, it'll pull to redline without issue. I'm now catching a cylinder 8 misfire on full throttle pulls as well, so plug wires are on the list now as well.

I suspect that I shorted something and fried one or more of the modules during the 1/0 install... I'm extremely careful and can't imagine doing it, but it's the only logical conclusion I can draw so far. Hopefully the Tech2 helps me to narrow that down...

 

[Tyrant]

Alright, the Tech2 emulator is extraordinarily helpful.

It hasn't given me any magical solutions, however it has identified and communicated properly with every system except for the TCCM (T-Case CM) and FPCM (Fuel Pump CM).

It's showing the expected failure to communicate for the Bose Amp (removed) and other features that the vehicle never came equipped with (ie electronic suspension/electronic lift gate).

 

[Tyrant]

It IS showing no communication for "Body control module (aux)", which I'm unsure of... Is there an auxiliary BCM? If so, is it tied to the ABS, TCCM, Traction Control, etc?