no 4x4

[whatever]

02 xls 4x4 changed dead battery, rainy day noticed 4x4 doesn't work.
checked fuses, connections to xfer case.any help would be appreciated.

 

[gijoecam]

the 4x4 system on the '02 is all controlled through the GEM. Without having it connected to an NGS tester and viewing the 4wd diagnostics, it's tough to tell where the problem lies....

Sorry I can't be more help.

-Joe

 

[Blee1099]

Welcome to the site. The Explorer 911 Forum is meant for situations where your truck is currently out of commission. Please read the rules of each forum and the FAQ so you understand what is and isn't allowed in each forum. You can read the rules of the 911 section by clicking on the following link http://www.explorerforum.com/forums/showthread.php?t=90274

Thank you.

In regards to the 4x4 system can you be more specific. When you push the button does the 4WD lights come on? If they do and it still doesn't go into 4WD, it may be the shift motor. I suggest being more descriptive.

 

[gijoecam]

In regards to the 4x4 system can you be more specific. When you push the button does the 4WD lights come on? If they do and it still doesn't go into 4WD, it may be the shift motor. I suggest being more descriptive.

Not likely... the second and third-gens don't use a shift motor to engage the 4wd, only to engage and disengage the planetary gearset for low range. Engagement of the transfer case (i.e. locking the front and rear driveshafts together) is accomplished by an electro-magnetic ball-ramp assembly. In the second-gens, it's engaged by either the TCS relay (low range/high range) or the TOD relay (control trac auto). On the third-gens, the transfer case has the same function internally, but is controlled by the GEM, eliminating the TCS relay and the TOD relay. (I guess technically they were just consolidated into the GEM, not really eliminated)

Basically, there are only three parts in his system: The switches, the GEM, and the transfer case. (I know, it also uses the wheel speed sensors and brake on-off switch, but either of those would present other problems too)

-Joe

 

[whatever]

when i push the button no hi or low light comes on

 

[kingrdh]

I have the exact same problem with my 02 xlt. I had to replace the battery, and now it won't go into 4x4 period. No lights, noise, or anything when the buttons are pressed. I have read that there have been some problems with the 4x4 control modules for the 2002 modules. I have also read that when the modules go bad the system may not throw a code. I would like to know if there is a way to verify if the module is bad before spending money on a new one.

 

[IZwack]

some1 correct me if im wrong but i dont remember seeing a sensor inside the transfer case to sense whether or not the electromagnetic coil is being powered up or not.. i guess the computer could check for an "open circuit"..

 

[gijoecam]

In the 2nd gens, the TOD relay or TCS relay energizes the coil and the power goes to ground through the chassis ground. In the 3rd gens, they re-routed the ground back through the GEM, so it knows whether or not the transfer case clutch coil is energizing or not. This is why the brown wire mod in the 3rd gens throws a code when you break the brown wire.

-Joe