4wd issues

[ramall]

Hey fellows,
I have the four position 4wd switch, when I move it out of 2wd nothing happens. No indicator lights come on, and the 4wd doesn't engage.
For awhile now the 4wd has randomly worked from time to time. When it works it's flawless. But now I've tried it a few days in a row and nothing.
Any ideas where to start?

 

[Jeepwalker]

Probably the first thing to do would be to hook up a scan tool and see if there are any codes. There are a few 'systems' and processes involved to get it into 4WD.

The way it works as I understand it: you turn the knob, it's hooked to the vehicle TCCM (Transfer Case Control Module) under the pass side dash. That handles the 'logic'. Then it sends a signal to the motor on the back of the transfer case. Not sure how much it is tied into the vehicle's computer (TIPM) other than the power for the motors and maybe monitoring the switch position. Possibly vehicle speed and other things are. Then there's a front axle 'connect/disconnect' and an electric motor slides a collar to engage the pass side of the front axle (connects it). There are switches to let the TCCM know when it has fully gone in various 'modes'. A flaky switch could also misreport.

The first and easy thing would be to check codes and look into any that you see. If you have a scan tool that gives real-time readings like AlphaOBD, you can see what's working or not working. But if you don't have that, check the fuse in the fusebox, and also check for voltage at the Transfer case motor. Disconnect the connector and make sure it's not corroded. Check for voltage. Might tap on the motor with a hammer handle (don't BEAT on the motor!!). The motor or the voltage going to it is probably the root issue as they don't get used a whole lot and are exposed to the NH winter elements. I'd probably start there after verifying the fuse good.

Might try working it back/fourth in/out of modes too. Maybe the seldom-used xfer case motor is just sticky and will start working with bit of use.

I bet there are a ton of Y/T videos which show how to de-bug this issue. Your problem has come up dozens of times over the yrs. Watch a few. Let us know the root issue when you get yours working.

 

[ramall]

Thanks Jeepwalker