I have a 2000 f150 extended cab 4x4 with ESOF. To start, I just changed the pass side exhaust manifold gaskets, due to an exhaust leak. While reinstalling the inner fender I pushed the vacuum lines for the 4x4 accuator against the hot manifold and melted them in two. I trimmed and spliced them back together and tried it out. No 4wd. To make it more confusing, I have had an intermittant problem with the truck not shifting into 4wd for several months, but had sort of forgotten about it, cause I haven't needed it this summer. So here's the facts:
-All the vacuum lines hold vacuum (testing with a hand vacuum pump)
-The vacuum from the intake is 22. Vacuum at the resovoir behind the battery box is 19. And at the line that goes from the resovoir to the solenoids its about 12.
-Both solenoids bench tested ok. The 2wd solenoid doesn't hold vacuum great (maybe a small crack in the body) but both of them open and close when actuated with 12volts from a battery charger.
-The pink (2wd) line always has vacuum, regardless of dash selector switch position, and the blue line(4wd) never does. So the solenoids (that seem to work on the bench) are not switching when 4h is selected.
-The actuator at the front axle works fine when vacuum is applied manually, and the front drive shaft does engage and disengage accordingly.
-When I switch from 2wd to 4h I hear a click up in the dash (which is normal), then a pause and about 6 more clicks (which is not normal) and then nothing. The 4x4 light on dash does not come on, but does work. I see it flash when I turn the ignition on.
-When switching from 2wd to 4h I feel no clicking at the solenoids.
-Fuse 23 was fine, but I switched it out just in case.


So alot of the individual parts seem to work. I have not done anything with the actual dash switch. Is there a procedure for testing it??

Also, I read about a poster that had similar problems and it turned out to be what he called a transmission range sensor switch. He said it was located on the front left side of transfer case. He had a msof system, and either the esof doesnt have this or I can't find it. Anybody know anything about this???

I don't know how to tell if the motor on the back of the transfer case is working. Thinking that maybe if it doesnt engage, then maybe the solenoids dont get the signal to provide vacuum to the 4wd side of the acuator. I did tap on it with a hammer while changing from 2wd to 4h to see if that would help break free. If its not working. Anyone know how to check this part for correct operation??

This thing is really kickin my butt, and any info, ideas or advice would be greatly appreciated. Thanks, Diggler

 

If you have not, read the first sticky on the page for 4x4.
Have you checked the #104 fuse that powers the transfer case motor?
The vacuum solenoids won't operate until the transfer motor goes to the first position 4H.
What tells the case motor to run is the GEM module.
What tells the GEM to function these parts is the dash switch.
All the same operation for 4L except how you get there from a stopped truck and the case motor rotates one more step changing the gear ratio and PCM shift sked..
Good luck.

 

I have read the sticky post on 4x4, I have not checked that fuse (but now I will) and thank you very much for the response and good information. Diggler

 

Turned out to be the transfer case shift motor. Thank you for the advice. Diggler

 

Your welcome.
Glad to be of help.
Good luck.