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I have a 2008 F250 SD 5.4L 4WD auto truck. I have a 4 WD issue and I am looking for a bit of info. I want to bench test the module but I am not sure about the encoder pins. I have the Mitchel wiring diagram. There are 4 encoder pins, one power and one reference. All 4 encoder pins have 12 volts. Zero volts on the other two. I want to simulate different feeds back to the module as they would be from the shifter motor. I already have set up something to simulate the different resistance values of the MSS.
I have watched a video of an F150 shift motor disassembly and all there is inside is a series of rings that go part way around except for one which does go completely around. I cannot find a similar video for the F250. The shifter motors have different P/Ns. Does the F250 shift motor have the same setup as the F150? It would make a difference if the F250 is using resistors similar to the MSS for each encoder pin. It is way too cold to actually remove the shifter motor to bench test it. I have a second module that I am using for this bench test procedure.
Any help would be appreciated
Last edited by Rangerforever; Jan 4, 2025 at 10:15 AM.
Reason: spelling mistake
The NV273 transfer case uses a Hall effect encoder with a wheel with magnets glued into it. This wheel has 5 possible positions in it, position 1 and 4 aren’t used but could still be read by the module (1 could be an Auto 4x4 mode for a different transfer case, 4 could be a neutral mode). The 5 thin magnets on the wheel only go over the D encoder and would most likely be tracking the wheel movement, the large magnetic can cover one or two positions (A, AB, B, BC, C). Hopefully the pictures help make sense of this.
I would recommend just pulling the 3 bolts off the shift motor and use that for testing as you’re going to spend a lot of time trying to duplicate the encoder positions and the movement of the wheel. Also if the module detects an impossible combination it will automatically revert to driving the motor all the way back to the 2H mechanical stop and then not move till the encoder makes sense again. I’ve had to manually power the shift motor to move it into the 4H/4L range to get those modules to try moving the shift motor again.
Do note that position 1 that is above 2H will cause the module to lock out the shift motor if you don’t have the motor connected to a transfer case and it tries to “home” to the mechanical 2H stop.
Note:depending on what literature you look at the OPEN and CLOSED could be swapped around
Thank you very much Ifrythings. I had looked at a video of a 2011 F150 shift motor and then compared P/N to see if it was the same as the F250 and it was not. I had seen a comment about using a Hall Effect sensor and what was in the F150 was not that at all. Taking the shift motor off will have to wait. Weather is cold for the next few days. Supposed to be quite mild next week, a high of -5C (+23F) so might take the motor off then. Will take your advice on testing and drop what I have been trying to do.
I folllowed all the PP tests and it pointed at the module. I ordered a used one and installed it but it was the same. Now are both modules no good or is there another problem? That is what got me to bench testing the module. All I have proven so far is that most components have voltage, either 12 volts or 5 volts. The 5V tells me the VR is working. Beyond that I have no way of knowing what is working right. If I can come up with a solution I may post it here. Might be others with a similar problem.
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