View Full Version : Waking up the TCM - 4wd switch not working
MichEnvoyBoy
09-01-2006, 02:14 PM
My 02 Envoy SLT has had this problem before - no lights on the 4wd selector. If you move the dial, you can hear the encoder motor working so I know its working.
Last time I read a thread *somewhere* on the net about "rewaking the TCM". Basically you pull a fuse out of the box while the truck is on, and put it back in and it "wakes up" the TCM.
Can somebody confirm which fuse this is? Im at work and my owners manual is at home (was referencing it last night for my power seat problem).
Thanks!
Envoy Fan
09-01-2006, 02:18 PM
Hope someone jumps on here and answers your problem soon.
BTW all owners manuals are available on line here, look under the "resources" tab top right of screen.
MichEnvoyBoy
09-01-2006, 03:44 PM
Well I went out and started the envoy, pulled the #8 ATC fuse and..... nothing. The "N" for neutral light comes on when you first start the truck but none of the other lights flash once as they usually do, or when you turn the dial.
So what gives? Is my switch faulty? Whats the consensus?
ScarabEpic22
09-02-2006, 03:50 AM
Either need a new switch, transmission encoder motor update, or a new encoder motor. Switches are ~$35, sftw reflash is probably $50-75, and new motor is ~$400+.
MichEnvoyBoy
09-02-2006, 03:09 PM
Well the good news is it is switching between (can hear encoder motor and physically feel the 4wd binding). I just find it so ironic that my power seat/heated seat problem and the 4wd indicator would both stop working at the same time :confused: Theres gotta be a link here.
Either way, again I went out and pulled #8 fuse for about a minute and it still didnt make the lights go back on the 4wd switch.
Ive been wiggling/inspecting wire connections for the past 2 days trying to figure out the power seat issue. I bet its the seat module. :undecided
MichEnvoyBoy
09-03-2006, 09:51 PM
Today I was frustrated with the 'Voy so for one last time, I started it up and started pulling the ATC fuse to see if it would rewake. That didnt do it, but I did pull a bunch of other important fuses (ECM 2, TBC, etc etc) and finally the lights came back on the switch, woo- hoo!
Now if I can just get my drivers power seat/heated seat to work :mad: Has anybody replaced their power seat module before?