Good Day!

I've been goggling for a week now, been reading how to trouble my problems on a Ford F150 Automatic 1999 Model.

Here's the problem, the 4x4 won't engage, i got diagnostic tool and here are the listed trouble codes.

P1804 - 4WD high indicator circuit failure
P1824 - 4WD clutch relay circuit failure
P1832 - Trans. Transfer Case 4WD Solenoid Circuit Failure
B1428 - Safety belt lamp circuit failure
B1398 - Left front power window relay circuit failure
P1815 - 4WD Mode select circuit short to ground
P1838 - Trans. Transfer Case shift motor circuit failure

This are all on GEM. I tried to erase the codes and replace the 4WD solenoid.

As i rescan, the DTC that was left are, P1815 B1398 P1838, and this result happens when i scan during 4H or 4L on the switch. On 2H there's only B1398 which is the window relay. Just after replacing the solenoid I was able to engage the 4x4 but the indicator light isn't showing on the dashboard but then after i turned off the vehicle and try to re-engage again it won't work anymore. I also tried to jumper the switch directly to the solenoid, it's engaging, but there's was another problem existed, there's a humming noise like its overreving sound on the engine and the speedometer is going up like crazy, like I am running for like 20 kmp but the speedometer gauge is going up already at 100 kmp, i switch back to original connection but the speedometer aren't back to normal, only the humming was gone, but there's another problem existed, the ABS light shows up. I scanned it and erase but it won't go. I also tried engaging the 4x4 w/o the GEM module while the switch is on original lines, the 4x4 are also engaging, and sometimes it will engage with GEM connected. I already checked the fuses and relays under the dash and on under the hoods, seems everything is fine. I wanna try to checked the lines from the switch of 4x4 to the module and from the module going to the solenoid lines.

Question: Am i missing something? Am i doing the right thing? What could possibly be the fault on why is the 4x4 not engaging and the dashboard light isn't showing.

Favor: Can anyone give me a diagram of the GEM module as well as the color coding of the wires?

I really appreciate any help coming from you guys.

 

If you don't want to deal with that is look into a posi lock. It's basically a replacement of the actuator. My understanding of this, as I did a little research as I considered this is that with the electronic differential, you choose 4hi/4lo and pull the cable, which puts it in the selected choice. My local 4x4 shop said i should only choose this if my actuator goes out. Is take a look and ask a couple shops, especially 4x4 shops. They could give you a better answer, but this might be worth a shot!

 

I already replaced the actuator, and my old actuator is also working fine, which is a waste cause i thought it was the actuator at the first place.

 

after work I'll see what I can pull up from prodemand and let you know

 

bump