P0785

Diagnostic Chart:

Wiring Diagram:

Circuit Description
The 3-2 Shift Solenoid Valve Assembly (3-2 SS Valve Assy.) 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 PCM 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 PCM 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 PCM detects a continuous open or short to ground in the 3-2 SS Valve Assy. circuit or the 3-2 SS Valve Assy., then DTC P0785 sets. DTC P0785 is a type A DTC.

Conditions for Setting the DTC

^ The system voltage is 10-16 volts.
^ The engine speed is greater than 450 RPM for 8 seconds.
^ Not in fuel cutoff.
^ All of the above conditions are met for 5 seconds and either of the following fail conditions occurs for 5 seconds:

- The PCM commands the solenoid ON and the voltage remains high (B+).
- The PCM commands the solenoid OFF and the voltage remains low (0 volts).

Action Taken When the DTC Sets

^ The PCM commands a soft landing to third gear.
^ The PCM commands maximum line pressure.
^ The PCM freezes shift adapts from being updated.
^ The PCM inhibits TCC engagement.
^ The PCM inhibits fourth gear if the transmission is in hot mode.
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).

Conditions for Clearing the MIL/DTC

^ The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

Diagnostic Aids

^ Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following conditions:

- A bent terminal
- A backed out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation

^ When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.

Test Description
The numbers below refer to the step numbers on the diagnostic chart.

4. This Step tests the ability of the PCM to control the solenoid.
5. This Step tests for power to the 3-2 SS Valve Assy.
7. This Step tests the ability of the PCM and wiring to control the ground circuit.
9. This Step tests the resistance of the Automatic Transmission Wiring Harness Assembly and the 3-2 SS Valve Assy.