DrivingInCircles

I'm aware that this thread is a bit dead, but I've been fighting this for a few months and have made little headway elsewhere.

I have an 08 Suburban 1500, 4WD. 130K miles currently, issues started at ~128K. Supercharged, with a 5" lift that both predate my ownership. I have had it since 120K or so.

After dealing with hard starts all winter (lows of -20°F), I pulled the corroded battery wiring and replaced it with marine rated 0 awg wire, which I properly crimped into tinned copper lugs. I did (later, after the issues started) add an additional 0 awg line before the distribution block for an audio upgrade.

I retained the factory routing for the wires that I replaced, measured resistance and continuity at every step, and fully removed the battery while routing the thick 0 awg wire.

Immediately following this, canbus codes U0102 (TCCM) and U0109 (ABS) popped up simultaneously. ABS, Brake, Traction Control, and 4WD service lights all came on at the same time.
time.

4WD high works, both in auto mode and when manually selecting 2WD and 4 high - Engagement confirmed, not merely the light. ABS and traction control do not work at all, under any conditions.

The vehicle intermittently starts in limp mode, typically during the first or second short trip of the day. This started around the same time, but is intermittent and typically stops after cycling the ignition a few times once warmed up. It's drivable, due to the additional power, but it's a nuisance.

I've confirmed the codes with a Snap-On bidirectional scanner (at a local shop), as well as my own Tech2 clone. Failed handshakes for both the ABS module and the TCCM module. No other ucodes are present.

I've cleaned and reseated the grounds for both modules (and others, while at it), blown every connection clean with compressed air, inspected for damage, and slathered with dielectric grease before reassembling. I have also replaced every single J case and mini blade fuse in both fuse blocks with new (quality) fuses. The only one that was blown was the fuse for the trailer lighting.

I measured resistance at the DLC, 120 ohms consistently. The terminating resistor above the spare tire tested at 120, so I assume that's good. I'm aware that the DLC should read 60, so I'm lost as to the cause of that discrepancy.

I'm running out of ideas... I'm not the type to throw parts at a problem until it goes away, but I'm unfortunately up against that wall now. After stumbling across this thread, I figured that the knowledge of the members here may help to fill the gaps in my own.

Thank you very much in advance!

Pjl

I bought my 2013 in 2015 for a suspiciously low price. I now know why. What I have found is that the truck goes into limp mode or starts throwing erroneous errors when the smallest thing is wrong and it's not fixed. For example, if I forget to reset the oil change gauge after so much time below 50% it will have this reaction. A wiring harness for a tail light did it once. A bad gas gap might have done it once. It starts with the stabilitrack warning, then limp mode, then engine light with codes from O2 sensor to evap etc. At one point the HVAC went crazy the the mechanic said I needed a new actuator. All this solved by figuring out the main issue (usually the oil change gauge). Why it does this, I still don't know. But it's made driving this truck for 8 years manageable.

MeatEater23

@Pjl Huh?

rsears10000@gmail.com

I am having the exact same problem currently with my 09 Tahoe. I spent 2500 on a new engine junction wire harness and probably 600 in 3 different inspections fees. Can’t keep dumping money into it but I have told multiple mechanics that I’ve noticed it happens when it gets hotter outside. If anyone has a fix for me I’d greatly appreciate it.