I get a car md code of p0785.

codes are OBDll and are available on line free you have seious transmission problems. Code scanner came with manual with codes in it.
https://obd2-codes.co/
https://www.obdadvisor.com/most-popular-obd2-codes/


https://www.obdadvisor.com/most-popular-obd2-codes/
https://www.yourmechanic.com/article/p0421-obd-ii-trouble-code-torque-converter-clutch-circuit-malfunction-by-andrew-quinn

https://www.yourmechanic.com/article/p0785-obd-ii-trouble-code-shift-timing-solenoid-malfunction-3-2-shift-solenoid-circuit-electrical-by-valerie-johnston

https://www.transmissionrepaircostguide.com/p1860/

https://www.yourmechanic.com/article/p0753-obd-ii-trouble-code-shift-solenoid-a-electrical-1-2-shift-solenoid-circuit-electrical-by-valerie-johnston

https://www.yourmechanic.com/article/p0758-obd-ii-trouble-code-shift-solenoid-b-electrical-2-3-shift-solenoid-circuit-electrical-by-yourmechanic

i dont think the inhibitor switch is bad (neutral park switch) seems like the cable is stuck in drive . so check cable first

P0700 is a generic transmission code

P0785 is a shift solenoid malfunction in the transmission probably 3-2 downshift. Someone will have to spend some time checking the decision tree for the P0785 code.

P0785 is a shift solenoid malfunction in the transmission probably 3-2 downshift. Someone will have to spend some time checking the decision tree for the P0785 code.

P0700 is a generic transmission fault code.

it's P0785
DTC P0785 3-2 Shift Solenoid Circuit Electrical (4.3L)
Rather then just replacing parts do you know how to do continuity checks on a electrical circuit ? IT could even be the driver inside the VCM - vehicle control module .
The 3-2 shift solenoid (SS) valve assembly is a normally-closed, 3-port, on/off device that controls the 3-2 downshift. The solenoid attaches to the control valve body within the transmission. The solenoid receives ignition voltage through circuit 1020. The vehicle control module (VCM) controls the solenoid by providing a ground path on circuit 687. During a 3-2 downshift, the 2-4 band applies as the 3-4 clutch releases. The VCM varies the timing between the 3-4 clutch release and the 2-4 band apply, depending on the vehicle speed and the throttle position.
When the VCM detects a continuous open, short to ground or short to power in the 3-2 SS valve assembly circuit, then DTC P0785 sets. DTC P0785 is a type A DTC.
You would need to see more codes for the ignition switch to be the problem .

How to diagnose bad GM truck Ignition Switch

P0785: Shift/Timing Solenoid Malfunction

- Low transmission fluid level
- Dirty transmission fluid
- Faulty shifting solenoid valve
- Shifting solenoid valve harness or connectors
- Shifting solenoid valve circuit is open or shorted

P1899 Park/Neutral position (switch) stuck in park or in gear

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 failure.

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 valvebody, etc...).

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.

All these code's are to your transmission, your mech needs to do more then pull code's, he needs to look at date on sensor to transmission before opening.

P0740 - Torque converter clutch solenoid circuit

P0758 - Shift solenoid (B) electrical

P0785 - Shift timing solenoid

P0761 - Shift solenoid (C) performance or stuck off

I would try Trans - X first pores right in to trans.

The most likely cause of this condition may be a loss of voltage to the transmission on circuit 1020. This loss of power may be caused by an open in the ignition switch. This condition my also be the result of an incorrect installation of an aftermarket electronic device such as a remote starter or alarm system.

There is a tsb on this problem:
TSB# 01-07-30-002D