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My truck is stuck in low range (low range light is on). It drives like a bus and won't shift.

What does it mean drives like a bus? Is it first time you have transfer case in "LO" How did it get there?

 

You'll probably think I'm lying but was just on by itself. It turns on and off by itself (like mentioned before). It's off for 3 seconds at times (even if I didn't put it in neutral).

 

When you say that do you mean just the light goes off or it physically disengages for 3 seconds?

If it disengages low then your motor is working, and Witek thinking about the module is on track. Have you left the sunroof open during a downpour?

 

Any chance something got spilled in center console? N78 resides just behind shifter.

 

Never spilled anything or had sunroof open

 

I am on my phone so don’t have access to the wiring diagrams. But if there is a relay involved here I wonder is it sticking shut? If there is try replacing/ swapping see if problem persists. Very inexpensive check.

 

No relays involved. Fuse F1f8 battery power, fuse F1f22 ignition on.

 

I'm out for the week; I'll try this when I get back. And I'll keep you guys posted

 

You ever fix this problem? I have 1999 Mercedes ML320 with the same problem

 

I had the same issue! I've never used low range, but one day when I started it, it was in low range.. It would set itself back randomly after a few seconds to a few minutes, but would kick the car in and out of low range randomly while I was driving.

I had to replace the Transfer Case Shift Motor (1635400888). I got it from eBay for ~$50 and replaced it myself under the car with minimal effort (like 5 bolts). To my knowledge, all that motor's job is to flip a hardware switch to make the car go back and forth from low range. The motors can go bad, loose, or get stuck. Mine was just loose I guess. I didn't have any codes for it on OBD, but sounds like yours is related. It's low cost and low effort to swap it out, I'd give it a shot. I used this video

No issues since

 

I had the same issue! I've never used low range, but one day when I started it, it was in low range.. It would set itself back randomly after a few seconds to a few minutes, but would kick the car in and out of low range randomly while I was driving.

I had to replace the Transfer Case Shift Motor (1635400888). I got it from eBay for ~$50 and replaced it myself under the car with minimal effort (like 5 bolts). To my knowledge, all that motor's job is to flip a hardware switch to make the car go back and forth from low range. The motors can go bad, loose, or get stuck. Mine was just loose I guess. I didn't have any codes for it on OBD, but sounds like yours is related. It's low cost and low effort to swap it out, I'd give it a shot. I used this video

No issues since

Ok I’m going to give it a try. I did unplug the tc motor because I read somewhere that it could be it. I cleaned it too see if any changes but I’m better off just getting a new one that way I can rule it out. Thank you hoping that’s the fix.

 

just chiming incase it helps anyone.

in the original post, what caught my attention is the "transfer case position is implausible " bit
so in this case,
1) I would probably clean the connectors/wiring, I assume one of these would carry the signal to tell if the position is low range engaged or not (if you have a scanner, it might be possible to see if live data can read the position, I have to try this myself as well)
2) failing that (its not a wiring/connectivity issue), then I'd look into exchanging the motor itself (assuming the transfer case position sensor in there somewhere is faulty) - but my best bet is #1 above especially if low range is not switched at all (if you have the time you can probably open up the motor to see what else could be wrong with it)

my truck's low range occasionally gets stuck and in some cases a light tap using a rubber mallet on the motor does the trick, ive read someone drilling a little hole and spraying some lubricant to temp fix this (reseal back after)

anyway, good luck, looking forward to some confirming what fixed the issue (for future reference of all readers including me, thank you)
I note that from @joco1555 its the replacement of the motor itself that fixed it

 

The only thing I’m wondering is difference between low range vs limp mode? In low range the transmission still shifts or remains in one gear? Because after bad transfer case switch out is where the low range or mode started for me.

 

Same or were there new codes after the swap? Because there’s a possibility that he gave you a faulty part. I wouldn’t know what else to check based on the codes

 

There are new codes are after swap. I took apart the center middle console to look at the transfer case control module and it looks so clean and untouched by any elements. What did look a bit dusty and dirty was the shift assembly.

 

Ok well new codes are pointing to the part that was replaced. I think you got a faulty part. Also piece you got replaced wasn’t the motor we identified earlier?