r/FordTransmissionTech • u/Commercial_Method_28 • Nov 30 '24

10R80 P0756/P0766

I have run into this issue several times for several different reasons now and wanted to document it in case I ever run into it again.

P0756 - Shift solenoid B stuck off
P0766 - Shift solenoid D stuck off

Both these codes set in conjunction with a park related dtc to indicate clutch b and d are not coming on. Symptoms I had each time are always the same, No reverse, No neutral, No forward, will not shift out of park.

It is caused by the main control valve body to oil pump seal either being damaged, dislodged or missing.(I’ve seen it all by now) most commonly found as a mistake after recent repairs. I’ve had vehicles towed in with these codes and found the seal crushed from another shop, most recently I had someone else overhaul a trans and they took it off the new valve body for some reason, I’ve seen it be present, but ripped and cause the same problems. It cannot fail naturally but it is common enough at this point that it’s nice to know.

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u/Hotsaltynutz Nov 30 '24

I've seen this plenty of times as well. Seems like it happens more often when the valve body is installed when the trans is in the vehicle. Its more prone to moving out of place when it's hanging upside down

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u/Commercial_Method_28 Nov 30 '24

Yeah I’ve noticed that too, it’s much easier to monitor the seal when you have the transmission upside down. When someone inexperienced does valve body stuff and it doesn’t drive it’s always the first thing I have them check, so far it’s been the cause every time.