Trouble service 4wd light 2004 Suburan- resets when restart most of the time, wont shift to 4wd when lights are out on dash or and service light is on, conections look good.

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GM 4WD Warning Light Issues - RepairPal

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Is your 4WD warning light on or a "Service 4WD System" message displayed? ...attempting to shift from 2WD high to 4WD low while the vehicle is moving), all the mode ... Resetting the TCCM may only be a temporary repair. ... The Bulb Check ...The mode switch on the dash will send a signal to the transfer case control ...

How To Override Stuck 4WD On A GMC Vehicle, Transfer ...

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https://www.youtube.com/watch?v=qNQOt_JP78U
Dec 29, 2014 - Uploaded by JamieJones TheCarMan
How To Override Stuck 4WD On A GMC Vehicle, Transfer CaseControl ... My 07 GMC Yukon is stuck in 4 wheel drive low, can I do this same process on it? .... has been changed, the module was reset, and the actuator were all replaced. ... is being slughish when i start off from red light or stop sign but after ...

Check the vacuum switch under the hood in the center of the firewall...follow vac diag

switch on dash can cause this but the transfer case control module is the culprit most times.try disconnecting battery this will should reset the TCM.see what happens.worst case senereo is bad transfer case

Well it could be the selector switch, but I doubt it.
Generally, the service light means something is not working that the computer controls. Solenoids and valves are a couple of possibilities.
The transfer case is shifted by solenoids commanded by the body computer based on the switch position on the dash.
You should be able to have a shop scan the body computer for trouble codes and proceed from there.
A basic code reader may not access the body computer.

Sounds like a defective electronic shift motor for the transfer case. The diff and t-case fluids should be replaced every 30K but will never turn on serv 4wd light.

I would advise you to check your fuses in the block under the hood and on the driver's side of your dash. If that doesn't fix your problem, you probably need a new transfer case selector motor. A quality aftermarket replacement can be purchased for around $250, and is fairly easy to change. Hope this helps!

What you have to do is go to a service shop and get the codes from the transfer case control module.This will help you find out what is causing the shifting problem.When the technician gets the codes there is a trouble chart that is followed to find the problem.Weather it be a sensor,wiring,switch,or wiring problem.This would be the best way to fix the vehicle other wise you are just throwing parts at it and this can be very costly.Unless you know someone with a scanner and a service manual this would help.Hope this helps.Let me know what you find out.Good luck.

Alot of times it's the electric shift motor on transfer case not working. With vehicle off key on press button and see if you hear it, next see if there is power down there when 4x4 is engaged. You haven't said exactly what your working on so if that's not the problem then you need to fill in some more info.

I questioned the dealer about my 2005 because mine was disengaging what I thought to be rough compared to what I was used to. They told me that I should shift the vehicle into Neutral before shifting the selector. I have also found that shifting between Reverse and Drive a couple of times while stopped has helped as well. By doing these couple of things, I have had no trouble since. I hope this helps as it might at least be something to try.

first the flashing light means that it is trying to go into 4wd. as far as i know there is no adjustment. The shift motor may be bad, If the transfer case is shifting it could be the silinod in the front differantal.