4x4 Problem

[nismotunedgtr]

Hello.

My 1993 XLT has 223,850 miles on her and runs like a top. Everything except 4x4 works.

The 4x4L light comes one at random times and goes off after a while.

If I press the 4x4hi button nothing happens, I even look under while my buddy was moving it slowly and the front driveshaft was not spinning.

Now, I pressed the test button on the 4x4 computer (rear by washer fluid) with the key in the on position and the red light came on and went off after 30 seconds. That is supposed to mean the computer has failed.

I have a 1992 XLT parts truck with 176k miles. I'm going to swap the 4x4 computer and see what happens.


What else could it be? Shift motor? Why does the 4x4L light come on?


Thanks!

 

[11lariat]

i'd guess the computer if it failed the self test..go ahead and swap it and see if it makes a difference..the 4x4 system is fairly simple on these, so if that doesnt do it i'd suspect a shift motor..and it may be a good idea to remove yours and clean it up/rebuild it BEFORE it fails on you..theres an excellent thread on how to do this if you search around the forum a bit

good luck..

 

[nismotunedgtr]

I replaced the computer and it passed the self test.

But the 4L light is still on and off on it's own. No 4x4 either.

I don't have the tools here (my mothers for the weekend) to remove the motor from the Tcase.


In two weeks when I'm back I'm putting in a passenger radius bracket and bushings. So I will do the shift moter then hopefully.


Why would the 4L light be on?

 

[Maniak]

I can't remember which light it was (4x4 or 4lo) but at one time I would see the light on when I knew the 4x4 wasn't engaged (the light was on, but not as bright as it would be when I had it engaged). In my case it was the connector on the back on the 4x4 switch on the dash. Some of the wires were loose in the connector. Since I fixed the connector I have never had the issue again.

~Mark

 

[DeRocha]

... I pressed the test button on the 4x4 computer (rear by washer fluid) with the key in the on position and the red light came on and went off after 30 seconds. That is supposed to mean the computer has failed.

What else could it be? Shift motor? Why does the 4x4L light come on?

The above is not accurate..
To accurately test test the 4x4 control module you need to:
1) Unplug the two connectors that plug directly into the module.
2) Turn the Key on
3) Push the button on the 4x4 control module.

The LED should flash four or five times and stop. If the LED flashed the four or five times, the module believes it is okay internally, and you’ll need to check the external parts like the 4X4 switch, shift motor, magnetic clutch and wiring harness. If the LED did not flash at all or kept flashing continually, the module is telling you that it is damaged internally.

Like Maniak the 4x4 indicator lights on my '93 (both 4H and 4L) have come on intermittently in the past, but with only partial intensity. It seams to occur more often in the cold, but it is nothing to worry about. After rebuilding my shift motor this partial illumination stopped for a year or so, but has recently started to occur again (a few times per month).