Here's a weird one...

[DJ BigDog]

So today while driving on an ugly PA road I hit a bone jarring pothole and the ** shut down for a split second, door's unlocked, CEL flashed on, it didn't seem to lose power completely but seemed like it reverted to just ignition on for a split second then everything returned to normal. It did this 2 more times on the drive, once at highway speed on interstate and once at about 45 on local road. All after big pothole hits. I already got under the dash and hood and check for loose connections at harnesses and lightly banged on the PCM to see if she'd shut off but couldn't duplicate issue. Any ideas from the brain trust on here? There's knowledge in numbers. Let's figure this out!

 

[ISU-152]

I'd pull the codes first. But maybe related to impact sensors if the truck shut down and unlocked the doors

 

[Rocket Man]

Ignition switch? Try jiggling it.

 

[iamdub]

Ignition switch? Try jiggling it.

My thoughts as well. I'm betting the OP has his locks programmed to unlock when the key is turned off.

Dan, grab your keys and/or fob as they hang out of the switch with the engine running and give 'em a few sharp tugs downward to see if it happens again. Speaking of, do you have a lot hanging (keys, fancy keyrings, etc.) out of the ignition switch? The weight of such items swinging and bouncing can take a toll on the lock cylinder/key switch.

 

[rockola1971]

Battery wires at the battery, starter and chassis ground connection. Check'em.

 

[RED TAHOE LS]

Battery wires at the battery, starter and chassis ground connection. Check'em.

Times two, GM battery cables are the worst, JMHO.
David g.

 

[iamdub]

Times two, GM battery cables are the worst, JMHO.
David g.

I agree that these are common problems and should be checked. But the locks unlocking when it happened is what leads me to suspect an intermittent connection in the ignition switch.

 

[rockola1971]

You mean the same symptom when a battery cable is loose (AKA Intermittent connection) spiking the BCM which can cause the locks to go Crazzeee.

 

[Rocket Man]

..

 

[ISU-152]

..

I feel the same

 

[Rocket Man]

I feel the same

Yeah sometimes it's not worth it, ya know.

 

[ISU-152]

Yeah sometimes it's not worth it, ya know.

Wut? I thought we were waiting on the conclusion together

 

[Rocket Man]

That too!

 

[DJ BigDog]

So update to the issue. I checked the potential issues mentioned in the thread already and found no obvious problems. Last night on the way home I hit a bump and it did its momentary power loss then shortly there after without any bump it did it again twice in a row. Later on after a stop the Tahoe went into limp mode, reduced power and disabled trac control alert on the display. tsc and engine light on... Managed to get another mile doing the shut down restart trick before it stayed in REP mode. I know that issue is typically either a harness or sensor issue at the TPS or a dirty throttle body so I guess could that have been the primary issue all along??? I plan on playing with TPS and TB this weekend to see what issue I have. Ideas?

 

[iamdub]

Shit just got real.

 

[DJ BigDog]

And the story is complete.... after taking it to a local garage that was stumped on the usual suspects that would be causing that issue I ended up with it at the dealership. They called a little bit ago and verdict is.... TAC Module!!!! $694 with diag, part and install. Thank god for a good autoclub membership that got me 3 free tow jobs or Id be out over a grand for this.... ugh oh well gotta do what you gotta do... thanks for all the input as always guys!

 

[iamdub]

Never would've guessed that.

 

[rockola1971]

WTH is a TAC module?

 

[Rocket Man]

Drive By Wire module.

 

[Tonyrodz]

Where's that located? Surprised that didn't throw a code.