Rear Differential Locking Up

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PT-4

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Backing out of garage and rear end locks up, literally feels like I backed into another vehicle. Put the vehicle in drive and then back into reverse, issue goes away. Only happens on cold starts. Rear differential or 4x4 issue?
2014 Ram with 5.7 Hemi and 4x4.
 
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PT-4

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No dash messages. 8-speed with rotary shifter. I honestly don't think it is the autopark feature. Truck remains in reverse and the R on the rotary shifter is not blinking.
 
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fireflymedic

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My 2014 won't back up if door is ajar and you don't have your seat belt on. Maybe the cold weather is causing door button not to signal door is closed. Of course if you have seat belt on this should not be activated anyway.
 

Travelin Ram

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My first thought was sticking door or seatbelt sensor due to cold. But in that case I would expect a dash indicator to light up.

Although it may be just a transient error signal; just there for a fraction of a second to trigger autopark and then gone again.

I think if there were any mechanical problem in the TC or rear diff sufficient to stop the truck it’s not going to just disappear when you change direction. There would be crunching and gnashing of teeth going on inside.
 

crazykid1994

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Mine has actually done that once or twice. Do you have limited slip rear? I pulled a few bushes and stumps out and I guess it locked the limited slip in and when I back up I could feel it binding like I had a solid axle. Once I pulled forward again and backed up it didn’t do it again. Does your truck have park sense?
 

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My 2014 won't back up if door is ajar and you don't have your seat belt on. Maybe the cold weather is causing door button not to signal door is closed. Of course if you have seat belt on this should not be activated anyway.
WHAT???? If that ain't ridiculous I dunno what is.
This coming from someone who isn't crazy about seat belts and can't stand any "controls" that force me to put it on before my vehicle is allowed to do what I am trying to make it do.
I work as a fleet mechanic, who unfortunately has to deal with Ford. So far I haven't had to do much more than oil changes on the '21s that are starting to trickle into the fleet but they do something equally ********.
When I pull anything on the lift I have to open the door and "sight it in" as I pull between the columns. Every damn time I open the door on a 21 f150 it puts itself in "park" right then and there. I can't hold the shifter in drive, the trucks in park before the shifter gets all the way to park position.

Anyway something to check out for your problem, something I see fairly often, (my mom's 98 intrepid did this too) is the park brake shoes within the rotor "hat" like to come unglued from the metal backing. Usually the friction falls off as I remove the rotor, and no harm done. But sometimes those linings wedge themselves in there and yeah it'll lock up the wheel. Switch directions and it dislodges, and you can roll.
 

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Mine has actually done that once or twice. Do you have limited slip rear? I pulled a few bushes and stumps out and I guess it locked the limited slip in and when I back up I could feel it binding like I had a solid axle. Once I pulled forward again and backed up it didn’t do it again. Does your truck have park sense?
That’s an excellent point. OP, are you going straight back in reverse, or turning as you reverse when this happens?
 
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PT-4

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Mine has actually done that once or twice. Do you have limited slip rear? I pulled a few bushes and stumps out and I guess it locked the limited slip in and when I back up I could feel it binding like I had a solid axle. Once I pulled forward again and backed up it didn’t do it again. Does your truck have park sense?
Yes, I do have parking sensors.
 

GTyankee

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If the gears were not meshing, you would hear a clanging noise 1 time, when it breaks the binding, but that usually happens with a Manual transmission.

I too think something Brake related is causing your binding
 

Trail Ryder

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I believe Ram recommends servicing the differentials every 50,000 miles or so. Hopefully, you have been doing that.
 

marks146

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Search for this stuff on Amazon. Not saying this will cure the problem, but it's worth a shot. I had some issues when turning sharply after I changed the rear diff fluid in my 2015. This cured my problems.

Genuine Mopar Fluid 4318060AC Limited Slip Additive - 4 oz. Bottle​

Manufacturer Part Number‎4318060AC
OEM Part Number‎04318060AB
 

62Blazer

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So the issue basically feels like somebody throws the trans in park and the truck jerks to a stop? Or maybe like you slam on the brakes?
If this was coming from the rear axle gears it would have to be a serious failure, like metal chunks floating around inside the fluid. There are no electronic devices, actuators, etc... inside the rear axle that would somehow activate and cause a severe lock up. The only time I have seen a rear diff do this is a chunk of metal floating around in the gear oil gets jammed in the gears, and going forward for a second allows the chunk to release. However it would probably happen at other times and cause other very noticeable issues. The limited slip possibly binding would not cause a sudden lock up, especially when back straight up. If you were turning in the reverse and the limited slip was bound up the tires would still roll/spin and you would feel it, but the truck could still move with the inside tire just spinning/slipping/chirping on the pavement. Same basic comments about the transfer case. There is nothing in a transfer case that you shift to that locks it up...like a transmission has a park, but the transfer case does not.
It's kinda' hard to tell without actually being at the truck, but sounds like maybe an autopark engaging? Does this have an autobrake engagement if it senses something in reverse?
 
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PT-4

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I was wondering the same thing. I thought the rear sensors were just a warning device, not something that would actually stop the truck.
 

Harley Harrold

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If the parking brake shoes brake friction material comes loose from the shoes they can jamb the rear rotor/s which is more likely to happen while backing up in reverse. I have heard of this happening to others.
 

Dean2

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I was wondering the same thing. I thought the rear sensors were just a warning device, not something that would actually stop the truck.
If you have Park Sense Active Braking as an option, the sensors will stop the truck hard. Being a 2014 1500 Laramie I am betting this is the issue. The fact it backs up after shifting to drive is one of the ways to overcome the Active Braking. If the OP has this happen again easy way to tell if it is active braking, put car in park, turn off sensors, put back in R, if it backs up now, it was the sensors. Turn off your park sensors as you back out of garage as it is reading the edge of the door opening as too close. Mine alerts red on the rear sensors every time I back out, but since I have active braking turned off on my 2500 it doesn't slam on the brakes. It does if it is on. Other option, as I said above, is to turn off your rear sensors when backing out. Then it won't activate the brakes either.

Found this video that explains it real well. It is also well explained in your owners manual but no one reads those. ;)

 
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