I had my 46re rebuilt back in November. About 3 weeks ago, check engine light came on, P0783 3-4 shift malfunction, but it still shifts into 4th. Took it back to the guy who rebuilt it, he swapped out the solenoids, reset the light. I had it 2 days, light comes back on, same code but still shifts normal. Puzzled since it shouldn't shift beyond 3rd gear with that code.

 

I am not completely sure what the PCM uses to determine when to set that code. I *think* it only allows a certain amount of time between when it commands 4th gear, and when it sees the RPM drop it expects...... I get the same code every now and then, I just reset codes, and forget it, trans shifts fine..... but, mine doesn't come back quite so quickly. Wonder if you have sticky valve in the valve body?

 

Take it back until he gets it right. If it was "rebuilt" i would assume that means all new solenoids/sensors. You may want to ask him about that. Could be an issue with the valve body.

 

 

"Some vehicles self-test the circuit even when the gear is not in use, the 3-4 shift solenoid may be an on / off solenoid, or duty cycle controlled. The PCM or TCM looks for an inductive kick to determine if the solenoid is functioning properly even when not in use. This brief activation is too fast for the solenoid to actually cause a shift in the transmission. When the solenoid is activated and turned off, the magnetic field collapses sending a slightly higher voltage to the PCM which is used to determine if the solenoid is functioning properly. Note: This DTC is nearly identical to P0781, P0782, and P0784.

Read more at: http://www.obd-codes.com/p0783
Copyright © OBD-Codes.com"

http://www.obd-codes.com/p0783

 

OOooo, interesting. Thank You.

 

2 different people suggested, unplug everything, clean the connections, put dielectric grease on it and reconnect.