Hey fellas, I have been trying to hunt down the issue with my 4wd. I have thus far done the following:

- Check and clean all fuses under dash
- Checked the underhood relays
- Check for proper operation at switch
- Opened relays under how and manually switch them, transfer case motor and lights on dash work as they should.

So my though is that I have power going everywhere. Something is not sending the signal to the relays. I would narrow this down to the 4wd control module behind the glove box. Is there any way to test this for sure? I'm about ready to just buy on and slap it in. Spending way too much time on this issue.

Thank you!

 

Tell us more about your truck. Engine?

Also, what leads you to the conclusion that your 4 wheel drive system is not working?

 

The truck has 5.4. I can not hear the relays or the 4wd motor engage when I switch it to either 4H or 4L. I get no voltage change to the relays when I switch it either. I'm guessing there is an issue between the switch and module or the module and the relays.

 

I found a wiring diagram of the input/output wires for the module. I tested each pin/wire going to the relays (BRN/WHT and ORG/LTBL). Discovered a spot in the ORG/LTBL wire that had worn through from the big positive cable that runs down the fender. Repaired wire and all is well. How crazy these silly electrical problems are! 4 days for a 2-minute fix. Anyhow, for future readers. Check the wiring harness/connectors on the driver's fender well under the hood. The wire had a hole with corrosion the size of pin head. I would never have seen it!

 

This is why my truck has a lever and manual hubs.

 

sad my truck was sold as the crap turn a dash **** with auto break hubs.
costs to much to swap over.
but for me transfer-case got stuck in 4w low. o now not sure if i should ever try and use low again? get stuck someplace in low can not get home. get to pavement and have to stop. (auto hub crap - can not lock them out).

 

This may not apply but it really helped me
https://www.ford-trucks.com/forums/9...97-2003-a.html