Serious 4x4 Problems

[ejbeach]

1999 explorer XLT 4.0 ohv automatic

Does anyone know if there are any relays that work the 4wd? I have a problem with flashing 4x4 lights when it is cold out. No problems in weather above 20 degrees F . When its cold I have no 4 wd and when I first start it I can hear something clicking over and over for a minute or so behind the dash in radio area. My 4 low won't work either. Changed motor and sensors with a used one, it engaged into low but wouldn't come back out. Got another used one, had same problem. Got mad, bought a new motor and both sensors changed it, only to have it lock into low and not come out again. I heard the relays click when I engaged 4 low, but get no clicks when switching back to high. Are the relays located somewhere or are they built into the GEM. I was gonna buy a new GEM but I think I will have to take it to ford to be reprogrammed if I remember correctly. Thanks for any help.

 

[Wrench]

It sounds like you have the 4405 T/C (4AWD) as you mention two speed sensors. You might be suffering from a broken shift fork. Can you manually shift the T/C into 2wd with shift motor removed?

 

[ejbeach]

yup, the transfer case itself is perfect, i am thinking about just changing the gem module. Today I have the opposite problem, now it's stuck in 4 high. When I turn sharp it feels like the front wheels are gonna rip off. If I disconnect the battery it works good for 2 days, then on the third day it starts to act up again. I think the module might be messed up and after resetting it, it last for a bit until it crashes again. I unplugged the module today and it defaulted to 2wd. I am having trouble finding a used module because it always seems that the ones I find have 1 digit or letter different than mine. Not sure how much it matters.

 

[gijoecam]

Well, the key to troubleshooting it is in diagnosing the problem, not throwing parts at it until it gets fixed.

You need to view the GEM PIDs to see what's triggering the 4wd in the first place. It's rare that the system can perform an uncommanded shift, but not impossible. A stuck relay could certainly do it, as could an intermittent connection telling the system that it's shifted to a place it's not. Without being able to view the inputs and outputs, it's tough to troubleshoot.

Unfortunately the only place I can guarantee they can accurately troubleshoot the system is the dealership. In a case like this, it's worth it to pay the hour diagnostic fee to let them pinpoint it, then do the work yourself. Otherwise, you could be just throwing good money after bad.

-Joe