Transfer case starts beeping then switches itself back to 2wd

Need help on my 4x4. I have replaced all 3 acuators. Front and back and 4 wheel still doesn't work. When I engage 4 hi the transfer case starts beeping and then switches it self back to 2 wheel. 4 low does nothing. Been trying to figure it out for months. Any help is appreciated. Thanks

 

What indication do you get on the indicator lights?

 

4 hi blinks when engaged.

 

Have you tried switching it to 4 wheel drive with just the key on, but the truck not running?

 

Has the problem remained the same the whole time? In other words, it’s doing the same thing now that it did before you replaced the actuators?

And, did it just stop working or was there something that may have caused it?

 

Yes. I've tried everything I can think of. It will go in to 4 hi and something in the transfer case starts beeping then automatically disengages.

 

Yes it has remained the same and Yes it just stop working one day.

 

The system has to go through a certain sequence. If it detects that something isn’t right, it will just go back to 2WD. But you already know that I’m sure.

If you have a factory service manual there is a troubleshooting procedure for the 4wd system. It’s pretty decent. You could go through those steps.

My 08 stopped working too and it turned out to be a mouse chewed thru a wire to the front ADD. I started by checking the voltages at the 4WD ECU on the passenger side behind the glove box. I wasn’t getting the correct readings. So then I just disconnected the ADD and 4WD ECU and checked continuity. Then it was just a matter of a visual check to find the broken wire.

Based on my experience I would check continuity of the harness between the ADD and ECU and the TC actuator and 4WD ECU. It is pretty easy to do with a helper and doesn’t take very long. That would at least eliminate the wiring and it’s doesn’t cost anything but time.

 

I'll try that. Thanks for your help

 

So did some investigating and my front acuator is not getting power. Guess I'll have to trace the wires down and hopefully find the problem.

 

I have an 08 too and the harness for the front ADD runs from the differential to the passengers side frame rail. You can see it on top of the frame in front of the spring mount. Then it runs up and back towards the firewall. My broken wire was visible from the passengers fender well.

 

Would you happen to have a wiring diagram for the front acuator to the main controller? I'm not finding any breaks or mice activity. I manually put a 12 volt power on the harness and it engaged in 4 wheel. I can't find any info on this. Thanks

 

Go to the “Electrical” forum. There is a sticky at the top. You will find a complete wire diagram for multiple years.

 

Thanks much!

 

So I couldn't visually see any breaks in the wires so bought a wire tracer and that thing is a game changer. Everything checks out good. So I'm thinking it's the 4x4 module. Does anyone know if or how it can be checked out to see if it's bad? Going to be testing the abs sensors as well.