Stuck in 4wd

[99164]

My son has a '98 explorer. It has the knob on the ads with three settings, Auto, 4 high and 4 low. I pulled the transfer case motor and it shows high, neutral and low. It seems to work fine. I can shift from 4 high to 4 low and back. But when I shift from 4 high to auto, it remains in 4 high. There are to hubs to unlock, I see nothing on the front of the transfer case except a medium size hose. The Haynes manual sucks, what can I test or check? The switch from the dealer is 59 and Advance and Napa can't get it. I tried disconnecting the battery, reverse, shifting in neutral, etc. Now what?

 

[drdoom]

Shift encoder only changes the range. Check the brown wire on the rear of case for voltage...IIRC it should be less than 1 volt at zero duty cycle and about 5.6 volts at full duty. Check that first....

 

[drdoom]

You can also use your LED test light...dim glow @ zero duty, bright when it kicks in or you switch to 4hi.

 

[99164]

The thick brown wire controls the 2wd to 4wd? What engages 4wd? If the voltage is low, should the t case be in 2wd? What raises and lowers the voltage? What is the root cause for the problem?

Thanks

 

[drdoom]

I would not call it a thick wire, probably 16ga or so...the brown wire energizes a powerful electromagnetic clutch, commanded by either your dash control, or automatically by the computer, when it detects a disparity between rear & front shaft rotational speed, by hall effect sensors on the case. The GEM plays a role in between there, but they rarely fail so I don't study on those much, personally.

 

[drdoom]

Sorry I don't know what is causing your issues....do you have any MILs on or flashing? Are all four of your tires an EXACT match, I mean exact in every respect: brand, model, size, inflation, & treadwear. Have you pulled the fuse for the 4wd system? Have you checked fluid, or hooked up to a good scanner?

 

[99164]

Tires are all the same and relatively new. I have no flashing lights and no codes. If I pull the fuse, it should remain in 2wd?

 

[drdoom]

Correct. Unless your clutch pack is blown.