Car: 2005 SRT6 Coupe 70,400miles

No previous transmission issues, always been smooth and fast.



Current Issue:

Was driving normally, no hard pulls or anything just casual driving. After about 20mins of driving I went to bump shifter into manual mode and nothing happened. I tried shifting up and down gears to no success and dash indicator still said D instead of a number for the current gear. About 30secs later hit a stop light and tried shifting into park and back to drive then trying to get into manual mode still no luck. Light turned green and the car made it 60yds before I lost all power to the ground. No loud noises or anything it was like suddenly I was in neutral. Pulled over and tried shifting into and out of park multiple times turning the car on and off the dash indicator stayed on D and eventually turned to a black square and locked the shift lever in Park and threw a CEL. I tried checking wiring and connections at the RCM as well as disconnecting the battery and letting it sit overnight with no luck. Scanner showed codes P0600, P0715, and P0720 all at once. I can get the car out of park by sticking something in the little trap door by the shifter but it never sounds like anything tries to engage and both reverse and drive act like neutral. I can rev the engine and push the car but nothing starts to engage so I had to tow the car home. I tried wiping the codes and issue is still present with black square for gear indicator. Never spilled anything in the car. Not sure if its relevant but for a while I had an intermittent code P0410 that would trip the CEL sometimes but hasn’t been present for several months.

From the OBD Scanner that was borrowed.

P0600 “SLA (Shift Level Assembly Module) CAN Message Incorrect / CAN Message Missing”
P0715 “Input Sensor Mismatch”
P0720 “CAN BUS Circuit”

I have seen threads of people with similar issues and one of the codes, getting fixed by either replacing RCM, the SLA shift assembly, Brake interlock solenoid, or the transmission conductor plate. However, I have not seen anyone throw all these codes at once. Also everyone with similar issues always seems to be able to drive the car still with the worst case being stuck in limp mode before fixing, I haven’t seen anyone that has no engagement in gear like I do.

So Im not sure where I should start looking first? I was also wondering if there is a way to test the functions of each part individually, especially the SLA I cant find anything on how to check if its good or bad everyone seems to just replace them and hope their issues resolve.

Thanks in advance!! Any help is greatly appreciated.