So the last time I was on the forum, my mom's 2008 Tahoe's ICE had to be entirely replaced at 32K, due to a fail bearing in the engine.

This time around we are in the replacement for that, a 2009 Tahoe Hybrid. So here is the run down of the afternoon/weekend.

Friday Afternoon: Oil Change at dealership. Then 150 mile drive out of town for the weekend. Mostly biking around so the car was parked.

Sunday Midday: 150 mile trip back home, no problems whatsoever. It is a hot day, 90 degrees. Tahoe is parked for 45 minutes. Get back in to run into town and flip the key. ICE comes on, but sounds rough, and is kind of buzzzing up in the rev range.

100 feet to the end of the driveway and stop to check the mail, ICE sounds horrible from outside, and then shuts off(like normal).

Decide to reverse back to garage and call my dad out. Put the Tahoe into reverse and the ICE does NOT come back on like it should. Get back to in front of the garage, put it in park my get my dad. Key off/ Key on, nothing but electric. He jumps in and puts it in drive and attempts to drive it around our 50x80 foot barn and cant get the ICE to come on no matter if his foot to the floor. Tried putting it in manual mode, which should engage the ICE and nothing. So after 2-3 minutes around he parks it and we decide to take it in monday morning.

Two hours later try it again and is running like normal. Anyone have an issue like this. No check engine lights or anything.

 

There seem to be a slew of issues that can cause problems with the ICE and starting. It can be a simple as the 12v battery going bad, to issues with the auxiliary wiring harness, and possible others too.

I had similar symptoms to you. First they discovered that the auxiliary wiring harness (which is the cable underneath the vehicle that gets routed down the frame under the driver's seat) was chaffed and shorting against the frame. After they fixed this, they found that the pins that connect this cable to the electronic brake control module were loose. They replaced these pins and soldered the new ones in place. Then the discovered that the other end of this harness - which apparently is behind the glove box - was also loose, so they replaced those pins. After all this work (and the accompanying 5 episodes like you describe), the truck has been a solid performer.

The hybrid system has an eight year warranty, so I'd have the dealer to a full diagnostic. I'd recommend, whatever they find to be wrong, to have them check the wiring harness for chaffing, and to check the connections at both ends - just to be on the safe side.

 

I understand all of the issues with these trucks not strting up because of the 12v battery and wiring harnesses and all of the electronics not being able to talk to each other.

But this wasn't a failure to start the vehicle. It was a failure of the ICE to come on. I could have driven for a mile or so until the 300v battery would have been drained but didnt. All accessories were working like normal. It was working as if it was an all electric car with a low top speed.