Hey all, I have searched hi and low and can’t find anyone with quite the same issue. Hopefully y’all can shed some light on it.
I have a 1997 f150 regular cab 4.6l v8 with electric 4x4 (switch in dash). I just recently got this truck, 4x4 hasn’t been working and the previous owner never fixed it. I got the truck for a hunting truck and will most likely need 4x4.
What it does or doesn’t do, turn the switch to 4x4 High or Low with it running in park, drive or neutral and nothing happens. No sound from the dash to lights on the dash nothing.
What ive done so far, I checked all fuses and they checked out. However fuse 20 and 21 have no power to them. Fuse 20 GEM module/Ctm module and power train control module PCM. Fuse 21 starter relay. Checked the actuators under the hood both have power and vacuum. Changed 4x4 switch no power at the 4x4 switch. Changed shift motor also no power at shift motor. Before I go and replace the fuse box and GEM what do y’all think it could be? Thanks

https://www.youtube.com/watch?time_continue=4&v=AWXiArMiqBw

Thanks, I should also add that I’ve watched all the videos on the issue as well. So from what I can tell there’s power where there’s supposed to be and vacuum there as well. I’m leaning towards the problem being electrical and between what ever supply’s power to the shift motor and switch.

Thanks. I’ve done some more research and found that the only power I’m gonna see at the switch is the light blue and red stripped wire when the lights are on and that it works on ground resistance not a positive signal. I should have mentioned these extra quirks in case they are related. The previous owner said that the driver side power window switch went bad and when he replaced it up on the switch puts the window down and down puts the window up. Also the odometer and trip does not work. From what I can tell all other gauges and needles work. Also I have seen where messing with the radio has caused a problem with the 4x4, this truck does have a after market radio in it. Thanks for the help.

Quick question, when I got this truck the 4x4 switch, shift motor and GEM we’re behind the seat. After replacing the 4x4 switch and shift motor still no 4x4. I poked my head behind the fuse panel and looked at the side of the GEM it has a Letter E on the side and says manual 4x4, is this correct? The one behind the seat has a letter c on it and it says electronic pickup 4x4. And just a reminder this has the esof 4x4 ( switch in dash). What do y’all think?

That’s what I thought. I’m assuming the previous owner replaced it with the first GEM he found. The electronic gem that was in the truck doesn’t look bad. May try putting it back in and go from there.

Alright guys 4x4 is fixed and working properly. Never fun going back after someone else’s butch work. Took the mechanical GEM and put the electronic GEM back in. Tested and everything is working as it should. Thanks for the help.