I have a 1998 5.4 supercab ESOF 4x4. When you turn the 4x4 switch no light, no click, nothing. Sometimes the 4x4 indicator light will come on if the switch is in 4x4 at the time you turn the key on. If the light does come on it doesn't go off when you switch it back to 2wd.I have searched and read through a lot of different threads on the 4x4.

I checked the Fuses first lol.

I have put a new switch on it that didn't help.

I checked the switch for power I am getting 12V on the wire for the park light, 3.9ish Volts in 4Hi and 2. ish in 4Lo, I went to my local dealer to ask how many volts should be on the switch and I got the "for $100 we can check it and probably tell you what is wrong."

The vacuum solenoids on the fire wall are clicking when you turn the key. Vacuum Lines look good no cracks or rubbed places that I can see.

I took the GEM out, it doesn't look like there is any moisture or corrosion in it. It looks good. I read to check the GEM "Orange/light blue is the wire for high and brown/white is the wire for low, they should be pin 16 and 17. Check those two wires for voltage when the switch is in those positions. You should check them both at both high and low just in case i'm wrong about which is high and low. If neither of them have voltage that doesn't mean it's bad. The wires should be nothing or power at rest and ground in high or low" that was from this forum I think.

So I did that and I am showing 12V all the time it doesn't show ground in 4HI or 4Lo. Does that mean that the GEM is bad? All of the other electronics seem to work. The only thing that is not working on the truck is the 4x4 and the Speedo is showing like 70MPH almost anytime the truck is moving.

Is there anything else I should check? I'm sorry to drag this out, but I wanted to show that I did search and put in some effort.

Any help is appreciated!!

Travis

 

Have you checked at the shift motor on the transfer case to see if you are getting power down to the motor? If you have power, then check the motor for intermittent short. If no power, then follow the line back up to the firewall and go from them backwards towards the switch until you find the problem. If the motor does engage, and you still have no 4x4, then you have to check the front shift solenoid down to the axle to find which part there isn't engaging the fork.

 

Thanks, first of all for the response!! I checked the motor no power, I am going to check it again just to make sure. Then I will track the wires back. So do you think its most likely not the GEM? I dunno if I checked it correctly.