My son-in-law and I are trying to troubleshoot his 2000 F150. When he puts the gearbox into 4hi or 4 low,It will not go into 4 wheel drive. I can bypass the GEM and ground the solenoid valve and the front locks and unlocks. On start, the bulb check for 4x4 and low range light and go out. Nothing lights up after that.
I checked all fuses, thevacuum system works right....
We replaced the GEM and still nothing. Any ideas?