Hard down shift/front wheels locking up?

Tiny
MIKEMIKE AMADOR
  • MEMBER
  • 2016 RAM 1500
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 200,342 MILES
When accelerating and letting off the gas pedal at between 40-45 mph the transmission feels like it gives sudden unexpected hard down shift and front wheels lock up feels as if I slammed on the breaks. Always happens at that certain speed of 40-45 mph
Wednesday, January 7th, 2026 AT 10:24 PM

6 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,475 POSTS
The first thing I would do so we are not chasing the wrong problem is to do a CAN scan, here is a video to watch.

CAN SCAN - https://youtu.be/u-4syLc-ifQ

Next, they have had problems with the transfer actuator motor not engaging or disengaging fully. You might want to disconnect the wiring to the actuator motor to see if the problem goes away or changes. Here is the location of the unit. Also, do you have all the same size tires on the truck? if not the traction control system will try to compensate and it makes the truck do strange things while driving. Also, do you have any warning lights on? There is a TSB telling of a software update for "Soften coast-down downshifts" so this can be the problem as well. Please check this out and get back to me so I can help you fix the problem. Check out the images (below).
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Thursday, January 8th, 2026 AT 9:32 AM
Tiny
MIKEMIKE AMADOR
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Thank you very much for the advice and response. So yes I've tried disconnecting the 4 wheel drive actuator motor but the problem didn't go away. And so I do have all same size and brand tires all the way around only thing I will say is that they are not stock, they are aftermarket and are 35 12.50R20 LT. No warning lights but if I do let it coast and let it do the jerk then it will throw a check engine light but doesn't stay on. It usually goes away when I turn the truck off for a bit. I have a scan tool, well I used alpha obd and even with no check engine light on codes do pop up using the scanner usually a p215c and p0721, also P1D92 and couple others but not always usually these are the ones that always come up after I clear them but they all say intermittent.
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Thursday, January 8th, 2026 AT 10:37 AM
Tiny
KEN L
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So these codes are pointing to the output shaft sensor for the transmission is not reading correctly, I would remove the sensor and check for metal shavings, clean the sensor and then re-install, clear the codes and test drive the truck. If that doesn't help replace the sensor.

P215C Vehicle Speed Sensor “B” - Output Shaft Speed Mismatch
P0721 Output Speed Sensor Range / Performance
P1D92 (RAM-specific) Drivetrain / TCM plausibility fault - The PCM & TCM don’t agree on vehicle speed data.

Here is the location of the sensor. Check out the images (below). Let us know how it goes
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Friday, January 9th, 2026 AT 9:11 AM
Tiny
MIKEMIKE AMADOR
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Thanks for the response, and yes that's what I've came up with as well that and I know the wheel hubs need to be replaced and those have the integrated wheel speed sensors so that can be effecting it as well. Only issue now is that the vehicle /transmission speed sensors input and output are located inside the transmission as part of the Valve body as I do have the ZF 8HP70 transmission in my 2016 Ram
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Friday, January 9th, 2026 AT 9:23 AM
Tiny
MIKEMIKE AMADOR
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I was thinking probably just replace the valve body/tcm as they are all part of one built in unit as part of the valve body as well as the speed sensors
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Friday, January 9th, 2026 AT 9:25 AM
Tiny
KEN L
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If the bearing hubs are out this can cause the traction control to act up so I would look at those as well. Is this a 3/4 o 1 ton truck?
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Friday, January 9th, 2026 AT 9:30 AM

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