08 Yukon Denali XL having electrical issues. Vehicle will not start.

[Sevs]

Mega fuse looks ok, I cleaned the cables in which were not in bad shape to begin with but got nothing. Fuse box does not seem to have any corrosion but have not checked underneath it. Ground cable from battery to engine unit does looks pretty clean and tight as well.

 

[2ndTahoe]

The other day our Denali starting freaking out, dash lights came door locks opening and closing. We parked the vehicle and the next day it won’t start. Check lights are all on, most gadgets, radio, etc work but hatch won’t open and vehicle will not start. Is this a TCM or ECM or BCM problem or can it be the neutral safety switch under the transmission? I did my research and all fingers are pointing to this, any feedback please.

Check my posts from March 2021 Strange goings on with my 2007 hoe. Would not start + a ghost in the works ( 2.5k rpm when shut down, 45mph at all times 65 0n the highway or backing into garage, various other weirdness ). Dealer replaced BCM and problem cleared

 

[Sevs]

Update my mechanic hooked up his charger directly to my cables and the car started. When my new battery was hooked up to the cables the truck would not start. He advised I replace the battery start the car and to drive it to his shop. He claims their is a short but to get it to him before something shorts again.

The new battery was drained from being parked for a couple weeks, some of you were very helpful if you can recall this thread, any advise would be appreciated!

 

[Doubeleive]

1st thing I said was Battery, replace it and do a drain test

 

[Just08yukxl]

The other day our Denali starting freaking out, dash lights came door locks opening and closing. We parked the vehicle and the next day it won’t start. Check lights are all on, most gadgets, radio, etc work but hatch won’t open and vehicle will not start. Is this a TCM or ECM or BCM problem or can it be the neutral safety switch under the transmission? I did my research and all fingers are pointing to this, any feedback please.

Mine was a few bad grounds by the tcm and stabilitrack computer under vehicle drivers side.

 

[Sevs]

What was the cost of the repair ?

 

[George Owens]

I’m having a similar issue but it says ecm lost connection even tho I’ve replace that already. Only time it would start is if I replugged in my range device but it will randomly act weird (the dash) and hard shift 1-2 gear and not let me drive any faster

 

[B-train]

No. Negative disconnect first always. Negative reconnect second always.