i just got a 1999 f150 4x4 and i am having problems with the 4x4.

i have been reading all over the net the past few days researching the problem before i posted something some were. but i haven't found anything exactly pertinent to my problems.

so here is whats up.

i turn the 4x4 **** and NOTHING, no lights, no klunks to jerks no noise at all. i have checked the fuses, the the power going to the dash switch and the power going the relays? or what ever it is behind the battery that has the wires and the vacume lines attached to it, and i have power to both when the switch is placed in the 4hi position. i have checked the connections, the wires the airlines ect ect. i even went to the wrecking yard and got a GEM module that i have been reading about ( i haven't put it in yet).

is there something that i am missing any suggestions?

 

Make sure the vacuum is actually getting to the vacuum diaphragm at the front diff. It is located in the front-center of the differential under a black plastic cover. It you jack the front of the vehicle up so the tires are off the ground you should be able to manually shift it in and out of 4wd (might have to spin a tire for the splines to mesh). If you are getting vacuum to the diaphram and it is still not shifting then the diaphragm itself may be bad. If the lines aren't supplying vacuum (or weak vacuum) work your way backward from there.

 

good idea thanks, so when it shifts via vacume the lights come on? or the other way around? i think i have been going at this the wrong way, i have been looking for the lights to come on and just assuming its an electrical issue when i don't get a 4hi or 4lo indicator on the dash.

 

Orrrrrr, you could try this thing...........

 

is that going to work on my truck?

what about the hubs being automatic?????