Help!! Tranny in limp mode, speedo inop and brake service requested

[rick88blaze]

I picked up an '03 GMC SLE Duramax last year for my tow rig. I haven't had any issues at all until this morning.

I fired it up to go get some breakfast this morning. On my way to the store I notice my gear indicator isn't working. I move the truck into neutral and back to drive at a stop light and then my brake and ABS lite come on and the dash reads "SERVICE BRAKE SYSTEM". BTW, the brakes work fine.

Then I notice that my truck won't shift out of first and the speedo quit working.

The truck runs and stops fine otherwise. All the fuses in under the hood look fine. I haven't check them for continuity yet.

Any help or advice would be greatly appreciated.

thanks,
Rick

 

[rick88blaze]

Oh yeah, there are no trouble codes on the OBDII computer.

 

[rick88blaze]

I pulled the fuses and they are all good. Some web sights are saying my NSBU switch is bad. That explains the range shift inhibited warning and gear indicator not lighting up, but doesn't explain the brake system warning.

Any ideas?

 

[kennyw]

I pulled the fuses and they are all good. Some web sights are saying my NSBU switch is bad. That explains the range shift inhibited warning and gear indicator not lighting up, but doesn't explain the brake system warning.

Any ideas?

Start with what you know if the part isn't too expensive and see if it fixes it.

 

[rick88blaze]

I got my truck back today. It ended up being just about the only fuse I didn't check. It was one of the ignition fuses in the cab. If I remember right he said it was the fuse that feeds ignition power to the tranny computer. I installed a backup camera a few months ago and it said to tie the monitor power into an ignition feed. Whoops.

I'm just glad it only cost me $80 instead of the $1200 they said a new computer would be.

Now I'll be wiring the screen straight to the battery feed under the hood with an inline fuse.

Thanks for the advice!!