Let me start off by saying that I know there are countless threads on several forums about this. But I have yet to find an answer that works, or symptoms that are identical. So I'll explain what I've got, and what I've tried.


2006 F150 FX4 5.4L auto w/electric shift 4x4.
This winter I had a battery drain problem. It took a ton of diagnostics, and during that it got to the point where there was no crank no start, etc. Short version, it was the fuse box. I replaced it, and got almost everything working. It still would not supply power to the fuel injectors, so I ran a temporary new wire, and it runs. No problem. That's the background.
Then I went to engage 4x4. For a while, the 4x4 lights on the dash would flash 3 times every 5 mins or so, but would not engage. Then it got to where they would not come on at all. I have replaced the 3 fuses in the cab fuse box, even though they appeared fine. I replaced the two relays under the hood with ones from a truck that worked. I replaced the selector switch in the cab. I tried tapping the shift motor in the T-case, and ended up replacing it with a used one that I knew worked (I have a good parts truck). I disconnected the (brand new) battery overnight. I have unplugged the 3 connectors at the PCM and inspected for corrosion, bent pins, etc. I have power at the selector switch. I have 14 volts at the shift motor. I have power on BOTH wires to the IWE solenoid, in both 2HI and 4HI. The vacuum does not shift to the second port in 2HI. I know the truck does not have a GEM.
There are several posts about checking resistance here, or voltage fluctuations there. But I haven't found a reliable wiring diagram to properly identify what pins where. And, I'm working by myself so watching the meter under the truck and turning the selector switch in the cab isn't real handy. So does anybody have a tried and true test procedure that shows me exactly which pins on the PCM to check for what? As that is about the only electrical component I haven't replaced, it seems the place to go next.

 

Sorry about the problems. I'm not a wiring or circuit guru, but I do know basics. I know electrical Gremlins are the worse. A few quick questions. Has the truck ever been under water? or do you use it to launch a boat, etc.? It almost sounds like you've got a Chaffed wire, or pinched wire somewhere? or a grounded wire. I know those are hard to find and diagnose. This past summer installed a Blue sea fuse block, and made a custom wire harness for some lighting on my '12 Polaris Ranger 800HD. While I was running the wires for the new lights, I discovered a pinched wire between the roll bar and cab for the spot lights on top of the cab that the dealer installed. It was bare at the pinch point but hadn't yet wore thru the paint on the roll bar to make the ground. If I hadn't of discovered that, it would of been a headache when it did. Point is, maybe you have a chaffed or pinched wire somewhere in the frame? just trying to come up with some food for thought.......

 

Maybe similar but I did a quick search and some people have had problems out of the Solenoid- on the psgr side firewall behind battery (this is the part that is frequently damaged by water...newer design has rain shield on top). Also check the shift motor on the transfer case.

Pic for help locating.
http://s756.photobucket.com/user/60D...ml?sort=3&o=13

not mine - I borrowed from another f150 forum.

 

I have been looking for some advice on a similar issue so I am going to leave this here as well. 2011 f 150 IWE is holding vacuum and have replaced the shift motor on the transfer case but only get the Orange wrench when I shift into either to or 4h. No noise nothing. No change in electrical input at shift motor or IWE. Have been through the fuse boxes many times all is good there. Is there another switch/relay/fuse in the system?

 

The solenoid and the shift motor have both been replaced

 

I appreciate the ideas. I just got the truck last year so I don't have much history on it. I haven't had it in water, myself. When I replaced the fuse box there was no sign of water or corrosion. The wiring will be almost impossible to trace without a proper wiring diagram. I'm hoping someone has one that shows which pins to check on the PCM.

 

I also checked the codes with an OBD II scanner. One pending code of a stuck O2 sensor. I pulled the coded from the dash display and got DTC D900, D950, 9352, and 9318. Not real helpful that way. They could be from before I put the new battery in.