2002 XLT No Power to Transfer Case Shift Motor

[snoopy2u]

I could use some insight! I'm in 4x4 low, hear a big "clunk" and the truck comes to a halt. Engine running fine - but, the truck will not move forward or in reverse. I tried to place it in park - had to kill the engine to avoid grinding gears. Came back later with a friends suggestion - started the engine, played with the 4x4 selector switch and was tapping the shift motor with my hammer. Got in the cab - put it in drive and she started to move. Noticed the 4x4 light flashing, got about 6 blocks and my baby died again. Same thing - no forward, no reverse, grinding trying to place it in park.

Got some ideas online - and had my local garage change out the transfer case shift motor. He tells me that he feels the new/replacement shift motor is not getting power. Did not tell me how he knew this or where he tried to measure voltage. Found a bad fuse somewhere, and know he was looking for a fuse or relay inside the dash. Bottom line is that - I can drive it now in "all wheel drive" - it appears to run fine. No problems putting her in park. However, I am told that I have lost my 4x4 capability. He simply exhausted his knowledge.

Does anyone have an idea as to what to look for? Can a shop hook this puppy up to a machine and read any "fault" codes to the relays, transfer case, shift motor etc??? I live somewhat rural and no Ford authorized dealers close by.

Is the wiring harness, plug and wires for a replacement shift motor's electrical connection the same as the factory shift motor? Is there any changing of wires, or should a replacement shift motor wire harness plug into the main harness without re-configuration to the plug or wires??? I read somewhere that you had to modify either the main harness plug or the shift motor harness plug wires for some unknow reason.

Where when I used to turn the key on and see " 4x4 and LOW RANGE" luminated on the dash - now I only see "LOW RANGE" lite up. Like as though the system does not see or sense the 4x4 capability any more.
The mechanic did not feel the transfer case was bad. But - could not figure out why the shift motor would not / does not energize.

 

[EngineerMike]

How many miles on the rig?
Mine was stuck in 4Lo @ 170k, had sloppy shifting for maybe 20k before it got absolutely stuck. Official Ford Xfer case motor was ~$250, bought a guaranteed fit replacement off rockauto or Ebay for $70. With Ford Pat iirc you have to remove 1 wire or maybe 3 from the OEM plugs & swap it over to the new because Ford criss-crossed the wiring between loom ends. Same basic motor part is used for multiple car brands & multiple models but with a variety of wiring configurations. So the generic part I bought needed to swap about 9 or so OEM wires. But sap 1 or swap 9, same thing, just repeat 8x & keep them in order. I did have to drill out the small wire holes on the bak of the generic plug that I needed (still more blank spots that I didn't need to drill out). Plenty of DIY vids online how to do this for Expy, etc.
FYI the 12V is 2 wires that go into the motor case, but depending on which way the motor is called to turn is plus/minus or minus/plus & the switch & electronics of the rig controls the swap. IIRC the were instances of the rotary switch being trouble. There are also vids online for bypass using a dual throw reversing toggle switch to bypass the OEM control but sill using OEM motor. The motor is almost never bad, the position sensor plates inside the reduction gear housing wear out the contact material waaaaay before the motor dies.

 

[snoopy2u]

Thanks for the reply. I've got some 137k miles on my truck. Since my post - I have had the shift motor replaced. Mechanic said the new shift motor was not getting power or 12v to the motor. He checked fuse 104 and it was good. He pulled the dash to find the relays - he did not see anything wrong. Was able to reset or do something that allows me to drive it in all wheel mode -but essentially - I have no 4x4 anymore. It least I've not tried to switch it in 4x4 for fear of needing a tow again. Mechanic went so far and his knowledge expired.

In going thru the web - I can hear the dash relays clicking when I turn the key on. I've read that this means the dash relays are working and sending a signal to the GEM module. From there I lose my understanding. I've checked the wiring on the new motor - still trying to confirm the location of two green and one grey with red stripe - as their location is difficult see in the video I've seen. Figured re-checking these wire locations was a proper thing to do. The motor came from Advance Auto - and interesting that you mention having to drill a hole in the plugs top plate for a wire location . As I was checking the wires I could see where two wires were so close together it looked like two wires in one top plate hole. But - it very well could have been a drilled hole that the mechanic needed to made, just drilled it slightly off center. This makes sense. Also, the new motor's top plate did not have numbered holes.

So, as I'm under the truck I see a three wire harness coming from the top of the Transfer case and another three wire harness on the lower part of the transfer case. What do those wires go to????? What device is those wires going to ??? They look like senors of some kind. Then there is a single brown I believe is a coil in the transfer case.

Do you know anything about these three wire sensors??? Is the single brown wire (hole 16) something that requires metering or testing of sorts. How would you test a coil wire??? Do you know where the GEM is located?? Can faults from the GEM be read??? Is the GEM something I can mess with???

Your comments lead me to understand these 3 wire sensors are positioning sensor plates. Is there a more precise term for them. If I attempt to order these, are they easy to replace. For the cost and time it may be reasonable to eliminate them as a fault by replacing them.

Your thoughts are important to me. Please share what knowledge you may have.