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Service 4WD light came on

21K views 46 replies 3 participants last post by  thehurtmac 
#1 ·
It's snowing like a mofo here in N.H., leaving the gym i decided to romp around in "auto 4wd" in the parking lot in my 2000 escalade, my service 4wd light came on after a few minutes, so i stopped messing around and went and got gas. Turned it back on and never came back on during the 10 mile drive home. Any clues? I've only had it for maybe 600-700 miles, haven't done any regular maintenance on it yet.
 
#4 ·
thehurtmac said:
it just blinks when i try to put it in 4low, blinks then goes solid when i press the other 3 buttons, sometimes the light will disappear and come on randomly, confusing as hell and no clue how to fix it
Replace the switch I know as I had a friend who works at the collage I go to and his trucks transfer case went into neutral when his four wheel drive control switches failed he replaced the switch and didn't have a problem
 
#6 ·
After 8 long months I finally got the new LM7 heart transplant. Its running rough because it hasnt been tuned yet and everything works except my 4wd...

I replaced the front solenoid and switch. All the lights on the switch blink once when I turn the key and that's it. I press and hold a button, nothing. I've yet to replace the rear diff solenoid but I have no clue why none if the lights come on.

Any clues?
 
#10 ·
I checked all the fuses. Pulled all 3 plugs to the T-case, they all have power or ground. It's getting tuned this week then I'll get a type 2 reader and figure it out. Sure is pissing me off though. The lights come on and go out when you turn on the ignition and that's it, and sometimes the lights don't even blink when you turn the key.
 
#11 ·
thehurtmac said:
I checked all the fuses. Pulled all 3 plugs to the T-case, they all have power or ground. It's getting tuned this week then I'll get a type 2 reader and figure it out. Sure is pissing me off though. The lights come on and go out when you turn on the ignition and that's it, and sometimes the lights don't even blink when you turn the key.
Check for voltage at the module
Its behind the headlight switch
 
#17 ·
thehurtmac said:
My buddy has a code reader that can read 4WD codes and he just told me the codes coming up are: C0308 - motor AB circuit low C0323 - t-case lock circuit low C0327 - encoder circuit low Time to do more research and call some dealerships.
I would check for loose ground wires before replacing any parts as those codes means a loose connection somewhere

I will look at my wiring diagrams and see where the ground wire is for the transfer case and its module and get back to you
 
#24 ·
I paid $115 for a new TCCM and now my 4WD works. Sort of. The 2HI light comes on and stay on, it shifts into AUTO 4WD, i can hear the actuator. I put it in 4HI but hear nothing, but says it's in 4HI (solid light on the switch) but will not go into 4LO, the light just blinks. Any thoughts?

Code that is coming up is C0323 - transfer case lock circuit low. I think it might be a bad encoder motor. Not quite sure, but at least the damn thing works now.
 
#25 ·
thehurtmac said:
I paid $115 for a new TCCM and now my 4WD works. Sort of. The 2HI light comes on and stay on, it shifts into AUTO 4WD, i can hear the actuator. I put it in 4HI but hear nothing, but says it's in 4HI (solid light on the switch) but will not go into 4LO, the light just blinks. Any thoughts? Code that is coming up is C0323 - transfer case lock circuit low. I think it might be a bad encoder motor. Not quite sure, but at least the damn thing works now.
Did you check the ground wire??
 
#26 ·
You never said exactly where the ground is, i need to know what both ends are attached to and the location of them. I got underneath it and looked for a ground coming off the rear t-case and saw nothing. Did the same thing to the front. There's no external ground from the t-cases to the frame.
 
#27 ·
thehurtmac said:
You never said exactly where the ground is, i need to know what both ends are attached to and the location of them. I got underneath it and looked for a ground coming off the rear t-case and saw nothing. Did the same thing to the front. There's no external ground from the t-cases to the frame.
Ok I will check in a bit and get back to you on the location of the ground
 
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