P1707-72 Code and Not Able to Move Vehicle Out of Park

cannondale900

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2015 LR4 SCV6 105k miles.

Two months ago my wife was unable to move car out of P to D. Had to use the EPR red lever behind the cupholder and eventually was able to operate vehicle normally. Assumed this was a glitch. Problem reoccurred yesterday.

Curious if any others have had similar issues and what the final diagnostic and fix was. New TCM seems the extreme end. Transfer case neutral switch could also be faulty? Not sure if there are mechanical bits involved as well.

Figured I'd check with the group here before putting on lift and digging in.
 

jlglr4

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f1racer328

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Two things come to mind: (1) brake pedal/light switch (under dash - tells car the brake pedal is depressed), and (2) the shift lock solenoid - this mechanism is supposed to unlock the shift knob when the brake is depressed, but there have been reports of it failing. This is a link to a fix for that problem: https://www.aulro.com/afvb/l319-discovery-3-and-4-a/275343-8-speed-shift-lock-solenoid-problems.html
If you turn on your ignition (don't start your engine, turn off the HVAC and radio) you can hear and feel the shift lock solenoid cycling when you press and release the brake pedal. Might be a super easy way to diagnose it for OP.
 

cannondale900

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Two things come to mind: (1) brake pedal/light switch (under dash - tells car the brake pedal is depressed), and (2) the shift lock solenoid - this mechanism is supposed to unlock the shift knob when the brake is depressed, but there have been reports of it failing. This is a link to a fix for that problem: https://www.aulro.com/afvb/l319-discovery-3-and-4-a/275343-8-speed-shift-lock-solenoid-problems.html

If you turn on your ignition (don't start your engine, turn off the HVAC and radio) you can hear and feel the shift lock solenoid cycling when you press and release the brake pedal. Might be a super easy way to diagnose it for OP.

Thanks all. I should have added to original e-mail.....brake lights work so it's not the brake pedal switch.

The shift lock solenoid has been particularly loud over the last few months. When the car was new you could not hear or feel the solenoid/actuation very much at all. Now the sound and feel is very pronounced. I assumed the code I would get due to a shift module fault would be different than P1707-72.

I imagine P1707-72 error is indicative of something faulty in the transmission status and because of that fault, it prevents the shift module from allowing the car to be shifted out of park.
 

jlglr4

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Just looked up the code in the manual. Seems to say it could be the parking brake release or the transmission control module. Pic of code description attached.
 

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cannondale900

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Finally had some time to spend on this....got tired of looking at the car sitting in the driveway for the last three weeks. The aulro post was very informative, thank you! I replaced the brake switch because they are cheap. No change. I performed the manual shift lock hack per aulro site. Car starts and operates just fine with the manual shift lock release hack. Car is now solely kicking out the P176C-11 code so I suspect something is wrong with the circuit board for the shifter module as the aulro post alludes to. I tested the shift lock solenoid and it worked when directly connected to a 9v battery. I tried re-soldering some of the circuits based on the aulro post but no luck. I ordered a refurb from ebay which will arrive next week. Will come back here with the results of having swapped out the shift control module.
 

Rover Range

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DTC P1707-72 is an internal short in the TCM. Work Shop Manual says to replace the TCM.
 

cannondale900

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DTC P1707-72 is an internal short in the TCM. Work Shop Manual says to replace the TCM.

Vehicle is no longer registering P1707-72.

I'm not sure how the failsafe logic between the TCM and the shift control module is designed. Is it possible that the shift control module has shorted out and its condition is being read by the TCM, therefore the TCM is preventing a signal to release the shift lock solenoid?

After the failure on 9/27 I used the manual release cable to put the vehicle in neutral and was towed home (half a mile) by a buddy. The shifter dial was stuck in the up position, in Drive, at the time of failure. Due to the shifter being in D, I could not start vehicle. Reading codes with ignition on I pulled many errors associated with driveline and related sensors (e.g. center locking diff, transfer case, and trans).
 

Rover Range

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The shifter being stuck in "D" is a good indication the TCM is bad.
Towing the vehicle 4 down, probably set all the driveline DTCs.
 

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