Electrical gremlins- BIG ones!

[MotoEric]

So….today I’m on the interstate after dropping off a bike for warranty service. As I’m pulling on to the ramp the door locks start cycling, the dash lights up and the OBDII port goes dead.
warning lights on:
CEL
Stability
ABS
gauges: d-dead j- jumpy o- on
speedo- d
tach-j
Fuel - j
volt -o
temp-d
blind spot- always on

windows/ roof OK
A/c fan OK- no compressor
horn-ok
tailgate - locked
starting is very intermittent . Usuall not even a click, then it starts and drives, no tranny kick- Down, stuck in a high gear.
made it home….barely….

I’m thinking bad ground, but you folks are the brain trust… Thanks in advance!!!

2012 Denali

 

[Joseph Garcia]

First, inspect your battery terminal connecting wires for corrosion (sometimes, they corrode from the inside out).

Then start with checking your grounds:
Engine to body ground
Interior passenger space ground on the outside frame under the driver's seat.

 

[petethepug]

If you have AWD verify that the wire harness behind the d/s front tire is not starting to wrap around the front driveshaft.

Inspect under the fuse panel in the engine compartment for corrosion and also that’s it’s torqued down to spec.

Lastly, and the easiest, charge the battery, out of the vehicle, on a slow charger and have a shop load test it for a bad cell.

 

[kbuskill]

These trucks are notorious for the battery cables corroding from the inside out. Even if they don't look bad.

I would take the opportunity to go ahead and do a Big 3 upgrade.

Next time it won't start, pop the hood and grab the battery cables and just move them around a little bit and see if it doesn't start afterwards.