Continuous C1405 Code Transfer Case Range Position Circuit High

Mike Owner Cromwell, Kentucky Posted   Latest  
Unsolved
Drivetrain
2007 Jeep Grand Cherokee SRT8 6.1L (3) 5-spd (W5A580) — 1J8HR78347C617502

this thing came in with a c1405 code. the signal wire for range position has 5.48 volts on it (as confirmed with voltmeter). so I checked all power and grounds and all are good. I load checked all wires from dtcm to transfer case motor, all was good. the 5 volt ref. has 5 volts (as confirmed with voltmeter). so I clipped signal wire at dtcm and it had 5.4 volts on the module side. (I thought at first this may be due to internal resistor, but thought it shouldn't be higher than the 5v ref?) so I installed new oe dtcm module. same thing. after rechecking everything, I then installed new oe shift motor. odd thing is, I had to turn transfer case shaft a little bit to bolt new motor on, and it registered seemingly correct voltage on scanner briefly, then it went back to 5.4 volts and sets codes continuously again. I though perhaps if the clutch pack inside is worn, it may let the motor overtravel, but there is a code for clutch pack worn, and it's never set it. and I wouldn't have thought the signal wire should ever be able to be more than the supply wire. any insight on this would be greatly appreciated. thanks in advance.

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Michael Owner/Technician
Grand Rapids, Michigan
Michael Default
 

These are noted for clutch failure causing code c1405. You can try to flush the t case with new fluid but if it works its just a bandaid. Many complaints and replaced t cases.

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Mike Owner
Cromwell, Kentucky
Mike Default
 

not doubting, but why would the signal voltage be higher than the 5 volt ref is supplying? in my mind, if the potentiometer is dropping voltage through the resistor and feeding back on the signal wire, why would it be higher than the original reference voltage? also, I've read many claimed that theirs would set code c1438 every time due to clutches worn because the motor overtraveling trying to…

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JJ Technician
Quincy, Massachusetts
JJ Default
   

My guess would be that it's a bias voltage to monitor the signal circuit, so it's seperate from the 5v supply. Open circuit voltage on the signal would be that 5.4v and short to ground would be 0v. Motor over travel could be causing the open by pushing the swipers off of the potentiometer. Did you happen to check the motor side of the clipped signal circuit? With that circuit clipped and an…

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Mike Owner
Cromwell, Kentucky
Mike Default
   

JJ, you are correct, there is 0 volts on the motor side, and first thing I done was jumper pin 2 and 3 and the voltage pulled to 0v. it does sound like what you're describing. I haven't had much experience with these, so I used the oe troubleshooting chart instead of using my head and figuring out through deductive reasoning, and it pointed me in the motor or module direction. some of these…

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Brandon Technician
Medina, Minnesota
Brandon Default
 

I can't speak to the potentiometer issue, but as far as the clutch goes - Chrysler does sell the clutch premounted on the shaft. The install job is fairly easy. We did a 2011 SRT8, fluid was black and burnt smelling. I don't remember what codes we got, but it was stuck in RWD.

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JJ Technician
Quincy, Massachusetts
JJ Default
 

I have the same problems diagnosing stuff sometimes. I end up thinking things over a little too much, and then end up with tunnel visioning on something. It's easier to think sitting here at a computer screen than it is when the boss is breathing down my neck to get something like this figured out in less than 20 minutes lol. I don't think any service information will talk about bias voltage…

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Mike Owner
Cromwell, Kentucky
Mike Default
 

I got the transfer case apart and it's exploded. the plates are not just burned but broken as well. I guess this is why it set the c1405 without ever setting the 1438 first. it probably broke and did't wear first. anyway, I was able to take the motor apart and rotate the encoder back into position. it appears everything is good there. now I've just gotta find a bunch of hard parts and lick my…

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