GEN 1 Transmission shifting problem

[FordTechOne]

Yes, the truck has only been serviced by a Ford Dealership.

For the valve:. Transmission diagnosis P0771 - replaced valve body / lead frame, bulk head connector - programmed shift strategy. This incident that caused this happened March 19th. Ford was closed the next day until May. I was able to have it towed to them May 11th, which is when the swapped the valve body.

June 10th I took it in for the check engine light. Tech found code P0636 Internal PCM failure. Replacement cost is $1415.00. The reprogram lasted less than 24 hours as the check engine light was on the next time I started the truck after leaving the dealership.

With the components already replaced, the issue clearly was not the valve body, lead frame, or PCM (which rarely ever fails). DTC P0771 sets when shift solenoid E (SSE) is commanded on, but the expected gear ratio change does not occur. The DTC charts calls out that this is a non-electrical DTC, meaning the fault is mechanically related, such as a failed SSE (which can be replaced without valve body/lead frame replacement at a part cost of $50-$60) or an internal transmission concern. A sticking valve in the main control (valve body) can also cause this DTC, but those valves can be manually inspected for concerns without unit replacement. SSE is only commanded on in 4th, 5th, and 6th gear. A failure of SSE or a corresponding component would explain why the truck downshifted out of 6th when the concern occurred.

I’d be very curious to know if there was any metal debris on the pan magnet, which would indicate an internal failure and rule out a valve body, solenoid, lead frame, or PCM failure. At this point, based on DTC alone and without knowing exactly which gears function or don’t, it sounds like an issue related to the Overdrive Clutch.

I wasn’t able to find DTC P0636; maybe they provided you the wrong DTC number?

 

[John Harshaw]

With the components already replaced, the issue clearly was not the valve body, lead frame, or PCM (which rarely ever fails). DTC P0771 sets when shift solenoid E (SSE) is commanded on, but the expected gear ratio change does not occur. The DTC charts calls out that this is a non-electrical DTC, meaning the fault is mechanically related, such as a failed SSE (which can be replaced without valve body/lead frame replacement at a part cost of $50-$60) or an internal transmission concern. A sticking valve in the main control (valve body) can also cause this DTC, but those valves can be manually inspected for concerns without unit replacement. SSE is only commanded on in 4th, 5th, and 6th gear. A failure of SSE or a corresponding component would explain why the truck downshifted out of 6th when the concern occurred.

I’d be very curious to know if there was any metal debris on the pan magnet, which would indicate an internal failure and rule out a valve body, solenoid, lead frame, or PCM failure. At this point, based on DTC alone and without knowing exactly which gears function or don’t, it sounds like an issue related to the Overdrive Clutch.

I wasn’t able to find DTC P0636; maybe they provided you the wrong DTC number?

They flushed the the transmission and replaced fluids. No debris or metal in the old fluids. Prior to getting the truck towed, it acted like I didn't have low gears (1-3). The truck would not move and the dash only showed 4-6 gear. With truck started, foot on brake, the truck would indicate that it was in 4th gear, but would not move. I tried to force it into a lower gear with the button on the shift knob, but that only made my gears disappear. I have the paperwork at home. I can double check the codes later tonight.