97 gmc sierra won't go into 4x4. Electronic

This is the only fuse that I can find that deals with the brake lights, but if that fuse had gone, you would have no throttle. My thought is a bad earth. More ideas here. It is a known issue.

https://www.google.com/search?q=1995+gmc+sierra+1500+fuse+3rd+Brake+Light+Cargo+Light+not+working

VEH STOP Vehicle Stoplamps, Brake Module, Electronic Throttle Control Module

Step by Step Troubleshooting 4wd 4x4 88-98 Chevy GMC ...

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https://www.youtube.com/watch?v=Su9Dkrfd_Zg
Jan 20, 2014 - Uploaded by rwdelling
Step by Step Troubleshooting 4wd 4x4 88-98 Chevy GMC Truck ... flashing indicator lights and then would not shift from 2-4wd atall. .... 1997 2dr Tahoe in Nov and I've been having the same problems all winter. I was getting worried thinking I would have to pay a lot of money to get my 4WD working again.

That 4x4 switch is powered through the incoder motor, see if the small motor by the 4x4 has power or not.

check the vacuum lines for cracks bend them a little when doing so to expose any hidden cracks make sure the end is on good.

Yes it will bolt up, but the electronic control will be different.

hope this helps

check for a bad brake light fuse! if not the fuse, the brake light switch operates brake lights and if bad you will not be able to shift it out of park, as well as the brake lights not coming on.! because you have to put foot on brake to do so. if bad switch, it wont let it out of park. it could be just out of adjustment also!! good-day !

code p 0654 refers to engine rpm output--circuit malfunction ===causes wiring ---ECM
code p 0650 refers to malfunction indicator lamp(MIL)--circuit malfunction====causes wiring --MIL---ECm
also refers to crankshaft position/cam shaft position sensor bank 1 sensor A --correlation===causes wiring---CKP sensor ---CMP sensor--mechanical fault

I had the same problem with the shift on the fly push-button 4x4 on my 97 Suburban. GM Shop manual indicates that it could be due to an encoder error on the actuator motor. Try pulling the transfer case fuse to reset the transfer case control module. Wait at least one minute. Re-install fuse then re-try operation. Did it last week and that saved me a trip to the dealership and extensive troubleshooting.

I had the same issue with my 99 sierra push button 4x4..to check the controller motor you can take it out of the side of the transfer case and using a 12v source check it on your own to see if that is what it is. You can also use an ohm meter on the conrtoller. If that checks out..try the Transfercase shift control modual. It really shouldnt matter what speed you are going for 4x4 high....Try to keep it under 80 though