First post so forgive me if I leave out any information.
I have a 1999 Jimmy 4wd, with the 4 button electronic selector switch on the dash(auto 4wd). The switch is illuminated, but none of the indicator lights on the switch are lit up. I've disconnected the battery, left that way for up to 2 hours, no change. Pulled the tccm out cleaned all the connectors, nothing. Replaced the dash switch, the vacuum switch on the firewall, and all vacuum lines. I have not changed the actuator under the battery tray. Fuses and relays are all good. Also, the parking brake light is on on the dash, no other lights, no service lights, nothing. I've searched for weeks online and haven't found any one with the same problem. Any help or direction would be greatly appreciated.

 

Do you get 4x4 when requested? Even if the indicator isn't lit?

 

I get nothing. No sound from transfer case nothing, it's in 2wd. I'm stumped.

 

I'd check the actuator next then. First thing I'd try is manually moving it to see if its stuck. If it isn't check for cracks or hissing when engaged.

Though not getting any lights is strange... When you replaced the switch, was it new or do you know if it was functioning with the lights and all

 

Actuator moves freely, however the spring looking piece on it looks... awful. Like it's stretched out maybe.

And the switch was brand new in the box. Returned it tried a second new one, right maybe the first was bad, same thing.
It's the brake system and 4wd systems related at all? Due to the auto 4wd?

 

I forgot about your brake light. Have you tried cycling your parking break to get the light to go out?
Or try lifting the pedal if it isn't returning all the way. If that doesn't do it, pull the kick panel off and ensure the sensor is plugged in to the pedal assembly.

As far as them being related, I actually have no idea on that. I'll defer to someone else on that one.

 

Also I would tend to think there is a communication issue between the switch and the tccm because of the lack of indicators, so I would keep looking there.

 

Pedal is coming all the way up. Sensor is plugged in. e brake is functioning.
How would I check the communication between the 4wd switch and tccm?

 

Have you checked all 4 fuses with a test light or volt meter?


Do not remove the fuses to test them.
Check both terminals on each fuse like this:





In the underhood fuse panel:
Test the CRANK 10 amp fuse & the ATC 20 amp fuse.
Both fuses must show battery voltage on both terminals at all times.


In the instrument panel fuse panel:
Test the 4WD (fuse #15) 10 amp fuse, & the GAUGES (fuse #4) 10 amp fuse.
Both fuses must show battery voltage on both terminals with the ignition in the RUN position.


Post your results.

 

Will do when I get home. Thanks!