Explorer repeatedly goes back an forth between 4wd and 2wd all by itself

[JimWithAFord]

Hi,

First I want to say this site is great! I just spent a couple of hours reading posts (I really liked the couple on ball joint replacement--witch Pics!).

My problem: while driving in 4wd/hi, my 2001 Explorer Sport will sometimes go into 2wd momentarily and then back to 4wd/hi. It may do this a few times. It never stays in 2wd long (usually about 1 to 5 seconds). I can hear the relays switching and have noticed the lights/indicators also confirm the switching. I don't think it flashes any error codes, but can't be sure because every time this has happened, I was in bad weather and had to pay attention to the road. This is quite intermittent, so I'm reluctant to take it to a garage. Also, when I drive in 2wd, it has NEVER switched back and forth on its own (thank goodness).

I'm thinking the problem is the switch itself because I hear the relays clicking. Now, I can't be sure, but over the years I think it mostly happens in the beginning of the winter season. Could the contacts of the switch be oxidized? I'm gonna try switching it back and forth a dozen times (engine off) to see if that helps. Anyways, I'm looking for any insight on this. I assume I have to pull the dash to replace the switch, so I'd like to make sure that's the problem...


Thanks much,


Jim

 

[gijoecam]

Ooooh, this is a tough one to troubleshoot... It could be the switch... If the resistance is on the edge and fluxuates between the proper resistance for the 2wd and 4high positions, it can cause what you're describing. That would show up as a flicker in the 4wd mode input PID in the GEM, but the only way to see what the GEM is seeing is with an NGS or WDS scanner. Any dealership would have it, but it's gonna cost (and may not reproduce while it's at the dealer).

The other possibility is that it's losing the position signal from the transfer case shift motor. A loose, dirty, or water-filled connector near the transfer case could cause that. It's pretty well-protected, but it can't hurt to crawl under there, pull it apart, clean it real good with contact cleaner, coat it with dielectric grease, and snap it back together. That alone might solve the problem.

Without knowing what the system is seeing for inputs and outputs, it's a guessing game at best...

Good luck!