1999 Ford F250 No 4 wheel Drive

Thanks for your response. Turned on ignition to run, turned switch, no sound from relays. Got helper, turned on ignition, put my fingers on top of relays by fire wall, had him turn the switch, nothing. Replaced both relays, no difference. Removed relays and checked for power where they plug in. 12V under both relays.

I have a wiring diagram. All roads lead to GEM. Any other options?

Thanks again. To summarize, when you put the 4x4 switch in 4Hi, it goes through the GEM, activates the relays to energize the TC motor to move TC lever. When you move the switch back to 2Hi, the relays are activated to reverse the motor to move the TC lever back to neutral. Position switches on the motor assembly stop the drive motor. Am I missing anything?

I ordered the GEM. Should be in next weeks sometime. I'll le you know how things go.

OK, installed new GEM. I've got more bells and dingers I didn't know I had. Turned on the ignition, turned switch to 4wd, it went to 4wd and 4wd light came on and I was feeling pretty happy. Until I tried to switch it back to 2wd. No luck. Now it's stuck in 2wd. Unplugged power wire to TC motor, checked wires. Both go to ground. Turned on ignition, turned 4wd switch, no power. Power to switch, all fuses good. Took to shop. They spent 3 days on it and gave up.

If anyone is interested, it's fixed. Took it to the Ford dealer and they tore into it. They came to the conclusion that a wire was bad. They unplugged the looms and stripped off the coverings. They found 4 broken wires and fixed them and put everything back together. About a 7 hour job. No explanation as to why the wires broke.

I have an 02 that blows the fuse immediatly. Checked the power the power at the relay and pin 30 has zero power. 87 has 12volts and so does 85. That doesn't seam ro be right

Thats what i thought. Not shore why its wired up like that. Ad soon as i put the relays in it blows the 30 amp fuse. Think i am going to send it into the auto mechanics to sort that out.