Not sure why you did not report P0771 in OP, or when I asked.
****P0771 came up 1 time. Once cleared, it never came on again.
I do recall a few reports of what "mud guys believed a defect", in the early 343 (98-02) IIRC pre May 2000 MFD. The biggest issue with the 750 (03-07). Was under filled from the factory. It was also believed a vent tube was allowing water in. But that may have been low fluid also.
I'll assume this is the donner transmission. A server wreck can cause damage to moving parts, dislodge connecting, etc. even those not directly impact. Was transmission pan pulled and inspection done?
**** Pan was not pulled or inspected in order not to void warranty.
Since you also said Dealership topped the transmission. BTW: This is no guarantee done correctly. Can we also assume you did not do the install yourself?
****Dealer topped off at proper temperature.
Are you doing the diagnostic or taking to someone?
****Dealer doing diagnostics.
Any other issues codes with your vehicle, any?
**** No other codes
Never thought about that. Makes sense!Since we both seem to be having a similar issue. Use this link for the FSM for our MY trucks. http://www.dustbird.com/ih8mud/FSM/Diagnostics.pdf CTRL + F for P0771. We have the a750F trans.
Also you should try the manual shift test. disconnect the wireharness on the outside of the transmission. You can shift using the shifter. This will tell you if the problem is mechanical or electrical