PLEASE HELP installed new ignition switch and key cylinder, now truck won't start

[XRipx]

2008 2500HD 6.0

 

Swapped out the switch and cylinder. Truck wouldn't start and had the "Theft Deterrent Service" message on. Went through the relearn process:

 

10 minutes ON (when message goes away)

5 seconds OFF

 

Repeat 2 more times

 

 

So I turn it to ACC and I can see the Theft Deterrent message and light are gone. Great. Go start it..... everything dies.

There's a tiny, brief turn from the starter, but the everything dies, no gauges or anything. Doesn't matter what position I put the key in. If I wiggle the battery wire, it turns back on, but then does the same thing if I try to start it.

It's basically acting like the battery is totally dead. Measured it with a multimeter, 11.5 volts. So now I have it sitting on a charger. If that doesn't do it, what else could it be??

Edited February 3, 2021 by XRipx

[Ian Mills]

11.5 is low but not usually low enough to prevent your gauges from coming on. Have you checked the condition of your positive battery cable? They have been known to corrode internally which can cause the truck to be totally dead and then it reconnects when you jiggle the battery cable. Just a thought.

[XRipx]

18 minutes ago, Ian Mills said:

11.5 is low but not usually low enough to prevent your gauges from coming on. Have you checked the condition of your positive battery cable? They have been known to corrode internally which can cause the truck to be totally dead and then it reconnects when you jiggle the battery cable. Just a thought.

Possible. I'll check it out. There was no sign of that before swapping out the switch and cylinder, though. So it would be a hell of a coincidence.

[BlancoSilverado]

25 minutes ago, XRipx said:

Possible. I'll check it out. There was no sign of that before swapping out the switch and cylinder, though. So it would be a hell of a coincidence.

Possibly, when you removed the battery you wiggled it and ruined the cable.

[XRipx]

OK, so I checked and rechecked pretty much every connection between the battery and fuse box. Nothing was adding up as everything seemed fine until I actually try to start the thing.

Talked to my mechanic, he said "I bet it's still the anti-theft system. Take it to Chevy"

Towed it to the Chevy dealership. Yup, just needed to reset the anti-theft system. 195 bucks. 

I asked them why the reset procedure I did at home didn't work. They basically said "Who knows? For some people it works, for some it doesn't."

Wonderful.