P0785 - Shift/Timing Solenoid Malfunction (3-2 shift solenoid is not working properly)
P1618 - Diagnostic Trouble Code (DTC) in another control module (in this case, in the Trans Module)
Flush the transmission, get any software upgrades available, reset the adaptors and try it, nothing to lose.
If it doesn't work you will need a transmission. Solenoids are internal, that's what controls the shifts.
They could be faulty or the valve body but one should always do what I
said once, if it doesn't fix it, you're looking at a transmission.
The resetting of adaptors is crucial if you update the software. It's basically wiping the memory of the TCU (transmission controller) and teaching it how to shift properly again.
Also could check this TSB...
The reason why I ask, is because anytime there are MULTIPLE
transmission solenoid codes, its usually the result of a failed ignition
switch. However, since only two codes appeared and were one at a time, I
think at this point, its unlikely the result of an ignition switch
P0785 is for the 3-2 downshift solenoid. Either
the solenoid is faulty, or something got damaged while the 1-2 solenoid
was being replaced. (connector knocked loose, wire rubbing on pan or
The 3-2 solenoid is #394 in the picture below, which is at the opposite end of the 1-2 solenoid.
P0785 is for the 3-2 solenoid and that is 394 in the picture. Is it
likely to fix it? yes, but of course I cannot guarantee that it will,
sitting behind my computer and never seeing the vehicle.
Hope this helps.