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Discussion Starter · #1 ·
Does anyone have a good wiring diagram Auto transmission for the transfer case mode sensor to the TCCM ? I would like to know were to check connections that may plug in and join it all together as I know about were it comes in to dash but want to make sure I am not missing something , I believe I have a break in the wiring but working alone its hard to use multi meter to ohm the mode sensor plug to were it plugs in the TCCM as one is under the truck an other in dash ,,I am sure there has to be at least one or more connecting plugs to get it into the cab were the TCCM is mounted,,looking for any plugs between the 2 areas if there are any,,I have traced a few feet of wiring underneath at mode sensor plug but nothing looks broken were I would have thought it would have caused issue ,,I have a transfer case mode sensor error , turn key on and 4wd selector switch lights up even neutral switch after that they all go out , if you look close they show real dim but nothing lights up when trying to select position and it has a new shift motor and cant get it to work
 

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Discussion Starter · #4 · (Edited)
Well got 4wd working but unsure how ..previous owner said had not worked in 2 years , and he had replaced shift motor once,,so I replaced the shift motor again found water in plug on motor side not mode side at that time few months back and then I replaced tccm an the fmc and still nothing , looked at wiring an found one wire on mode sensor plug that had been spliced poorly,,I repaired that still nothing,,that's when I posted this,,ok so before tracing wires down I unplugged mode sensor an turned key on an checked the #2 pin for the proper 5volts an all was good,,checked the #4 pin for ground and it ohmed out with a frame test just fine,,then checked other mode position pins by ohming out all pins to see if they might be touching together somewhere but all was good no shorts that could be found with that test,,so turned off key and climbed back under and plugged mode sensor back up,,was going to start looking at plug connections but first jumped back in truck and turned key on really just for the hell of it and low an behold the 2wd light came on at the selector switch ,,I was like what the hell ,,turned to 4wd an boom it went in could hear shift motor turn,,worked in low an high an 4wd light was on when engaged and the 4wd service light out,,so took it out for long drive and its been working ever since,,so go figure but I guess the ohm test on the ground to frame on #4 pin woke it up as I had always thought it was a grounding issue but never thought this would do it as it hadn't worked in 2 years but now no problems :icon_peace:
 

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Greg
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Well done.. sounds like a combination of bad connections.
 

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Discussion Starter · #6 ·
Well done.. sounds like a combination of bad connections.
Maybe, but its still weird , did most work a few months back then till today was doing nothing until testing ground an power wires to plug,,trying for the past few months ,,I had unplugged the mode sensor a dozen or more times also past few months checking everything an getting nothing,,
I could use my handheld and clear the error code an service 4wd light would go out for 30sec. an back on,tried this dozens of times ,didn't even have to start the engine an service light back on,,now just by ohming wires doing no repair it starts working
 

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Greg
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I can't difinitively give an answer but I have had a ground fault causing the pcm to stop responding fixed the problem and it still didn't work. Then the pcm would reset activating the circuit and it work. It was like it went into self protection mode and then reactivated. Magic...
 

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Discussion Starter · #8 · (Edited)
I can't difinitively give an answer but I have had a ground fault causing the pcm to stop responding fixed the problem and it still didn't work. Then the pcm would reset activating the circuit and it work. It was like it went into self protection mode and then reactivated. Magic...

Yes I agree ,All I could think of is when I ohmed mode sensor frame wire on wiring harness side to clean bare frame were I cleaned it that it made the circuit stronger perhaps as electric needs a ground to work properly ,through the ECM or TCCM as the key was in the on position and this perhaps helped reset or gave enough boost to start working again like a safety instead of frying a circuit it closed as the water in shift motor plug would have made a short in system causing a blown fuse or shutting it down like a ground fault as you say ,,back when previous owner had the truck
 

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Greg
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I agree..
 

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Greg
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Thats better mileage than most. The old girls are fun to drive..
 

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Discussion Starter · #12 ·
been away awhile on this forum to many projects , but I did away with the electric shift , found a floor shift and was able to take the piece out of the electric actuator an cut off the piece that goes onto side of transfer case , I welded it to the lever that came with shifter and was able to convert very easy , had to flip over so linkage clears so pattern is backwards but works flawlessly now for past 4 years
 
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