4R70W Transmission Problem

[Ten2ndNova]

Only sometimes it does this but when the o/d off light is flashing the car seems like it is trying to leave in third gear but is you manually shift it it seems to work just fine. But as soon as the light goes solid it works fine in drive. It pulled up two codes the first one is
0755 -shift solenoid b malfunction
0758 -shift solenoid b electrical


Does anybody have any ideas that can help me figure this out..

The car is a 2000 mustang gt with a 04 cobra 32v engine and a 4r70w transmission.....

 

[chuck943]

That could be a bad shift solenoid B, Lead frame (plastic harness inside trans pan that hooks to the solenoids), wiring harness, or PCM driver circuit.
If you want to try parts first yourself replace shift solenoid B and the lead frame.

If you have a way to do active commands with a scan tool you can pull pan and activate the solenoid B and see if you get a voltage drop across it and see if you can feel it activate.