Just had a 'limp event' with my CT6 on either the 1-2 or 2-3 shift (wasn't paying attention at the time), so I limped into the nearest parking lot and power cycled the car, after which it returned to shifting ok. Got it home and pulled info with GDS2, and found the P0777, so Monday, I'm going to talk to my dealer about getting it in, but my question for the experts here, which valve or valves are involved in the lovely recall on the 10L's? I haven't had any highway wheel lockup, this was right after pulling out of my daughters school, but could this be a sign of the wear that causes the 'wheel lockup'?
10L80 P0777
- Thread starter Cougar281
- Start date
From what I've seen, they're replacing the valve bodies. There is about 4 renditions in part numbers noted in the last 90 days. Kind of like the CP 4 I guess.
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From what I've gathered, the recall issue isn't actually a lockup, but the transmission shifting to second, which at highway speed, would feel like it locked up. From looking at a clutch application chart, it does appear it COULD be related. From what I've read, it seems the 'lockup' can occur on the 8-7 shift. In 8th, clutches B, D, E & F are applied, in 7th, C, D, E & F are applied, and in 2nd, A, B, C & D are applied... Of course if the clutches for 7th are applied and clutch B stuck, you'd have clutches B-F applied at the same time 
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That sure sounds reasonable. I've been working with someone who trades around in these used 10L's every day. Have a 2019 Gen1 valve body he sent me, and just received the new style range switch, speed sensors, and valve body harness from the Gen2 version. The Gen2 valve body has an extra solenoid, and is controlled by the T93 TCM.
To run a Gen2 valve body version with a T87A, ya have to ground that extra solenoid wire, which would be PWM controlled by the TCM. If not, it acts weirder that just randomly snagging 2nd gear. On jackstands, R was spinning Forward, N was freewheel, but D range was a Trans Brake. Locked up tight... Is on a fully custom 10L90 with two piece converter and bunch of new internals. So my first thought was some mismatch in hardware. Nope, just a single solenoid not opening when it should causes all types of weird responses in these units...
Word on street is the valves are loose in the bores, allowing them to cock sideways enough to hang the slider. Learning what I have so far about these bodies, and how the Ford and GM are basically identical internals, why isn't Fords seeing this same issue??
To run a Gen2 valve body version with a T87A, ya have to ground that extra solenoid wire, which would be PWM controlled by the TCM. If not, it acts weirder that just randomly snagging 2nd gear. On jackstands, R was spinning Forward, N was freewheel, but D range was a Trans Brake. Locked up tight... Is on a fully custom 10L90 with two piece converter and bunch of new internals. So my first thought was some mismatch in hardware. Nope, just a single solenoid not opening when it should causes all types of weird responses in these units...
Word on street is the valves are loose in the bores, allowing them to cock sideways enough to hang the slider. Learning what I have so far about these bodies, and how the Ford and GM are basically identical internals, why isn't Fords seeing this same issue??
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There was a video on YouTube comparing the two. They are very similar in design but not identical as I dont think the parts are interchangeable. It looked like GM just went cheap with everything, and Ford did not. I'll see if I can dig it up.