1997 Ford F150 4.6L with ESOF. 4 wheel drive works fine, engages and disengages with the switch as designed. However, while driving the relay randomly clicks on and off and the 4HI and 4LO lights on the dash turn on and off as the relay clicks. It does not engage the 4x4 when this happens.

I might not be using the correct word when I say "relay". Does not sound like it is coming from the fuse panel area, it is closer to the underside or just to the right of the steering column, (the clicking noise). Any thoughts?
Thanks

 

I take that back. The clicking noise when it randomly turns on and off sounds like it is coming from the fuse panel area. The clicking when I turn it on manually with the switch is closer to the area behind the switch. Sounds like a faulty GEM, maybe?

 

Does this sit outside often, or has recently been out in the rain or heavy snow? if yes...is the floor board on the drivers side damp or wet? If yes...then you probably have a windshield leak. You'll need to address that before addressing your electrical . Have you noticed any other ODD electrical happenings?

 

The relay you hear is under the center part of the dash.
The 4H, 4L lights will go out if the transfer case motor goes back to 2H.
This is because the case motor is part of the lamp circuits and firewall solenoids.
What is happening is your GEM is causing the relays to operate falsely hence the case motor.
Look for a leaking windshield dropping water into the GEM module.
It's located on the back side of the dash fuse panel.
Good luck.

 

Definitely possible, it does sit outside. The only other odd electrical problem is the wiper/wiper delay switch on the steering column is finicky but that is probably unrelated.
Thanks for the reply

 

Great, I just watched a video of a guy trying to remove the GEM. Not fun!!!

Like I said I'm pretty sure the 4x4 does not engage when the random clicking is happening, so I assume it is just the GEM making the noise, the closer I listen it is coming from the fuse panel area.
Thanks for the reply.

 

There are two different relays involved in the 4x4 system in addition to the GEM module. The transfer case motor relay is under the center of the dash, back up behind the radio, and there is the relay for the transfer case clutch under the right side of the dash. Both relays are controlled by the GEM module.

It would be to your advantage to pin down the source of the clicking as accurately as you can.

 

Would love to know too, my 97 2WD does the same thing. Everything works great it just clicks.