2002 Explr.. 4wd switch dead?

[phil a]

I tried to use the 4wd sunday. and no engagement , no dash light or console warning lights, hasnt been used in 2 years or so.. fuse is good.!
Could this be just a switch or relay stuck due to non use.?
Where do you start at this point. (under car)? or not?

[shorod]

It appears that most of the controls for the four wheel drive switch is controlled via the four wheel drive control module. The switch has three resistors internally that determine which mode the four wheel drive control module should operate in, either Auto, 4WD high, or 4WD low.

The four wheel drive control module then commands the transfer case magnetic clutch assembly to engage the various selections.

The four wheel drive control module is located behind the glove box and is part of the data link network.

The most reliable step would be to find someone with a high end scan tool that can read codes from the transfer case controls and monitor inputs and outputs in real time.

-Rod