DTC P0785 3-2 Shift Solenoid Circuit Electrical 2.2L
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 Powertrain Control Module (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 8-16 volts. |
| • | The engine speed is greater than 450 RPM for 5 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 input remains high (B+). |
| - | The PCM commands the solenoid OFF and the voltage input remains low (0 volts). |
Action Taken When the DTC Sets
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
| • | The PCM commands a soft landing to third gear. |
| • | The PCM commands maximum line pressure. |
| • | The PCM inhibits TCC engagement. |
| • | The PCM inhibits fourth gear if the transmission is in hot mode. |
| • | The PCM freezes shift adapts from being updated. |
| • | DTC P0785 stores in PCM history. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after three consecutive trips 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 at the PCM, the transmission connector and all other circuit connecting points 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 |
| - | Moisture intrusion |
| - | Corrosion |
| • | 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 table.
-
This step tests the ability of the PCM to control the solenoid.
-
This step tests for power to the 3-2 SS Valve Assembly.
-
This step tests the ability of the PCM and wiring to control the ground circuit.
-
This step tests the resistance of the Automatic Transmission Wiring Harness Assembly (A/T Wiring Harness Assembly) and the 3-2 SS Valve Assembly.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Powertrain OBD System Check in Engine Controls | |||||||
2 |
Important:: Before clearing the DTC(s), use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM. Are DTCs P0740, P0753, P0758, and P1860 also set? | -- | ||||||||
3 |
Refer to General Electrical Diagnosis Procedures in Wiring Systems. Did you find a short to ground condition? | -- | ||||||||
Using the transmission output control function on the scan tool, command the 3-2 SS Valve Assembly. ON and OFF three times, while listening to the bottom of the transmission pan (a stethoscope may be necessary). Does the solenoid click when commanded? | -- | Go to Diagnostic Aids | ||||||||
Is the test lamp ON? | -- | |||||||||
6 | Repair the open or short to ground in ignition feed circuit 1020 (PNK) to the 3-2 SS Valve Assembly. Refer to General Electrical Diagnosis Procedures in Wiring Systems. Is the repair complete? | -- | -- | |||||||
Is the test lamp ON when the solenoid is commanded ON, and OFF when the solenoid is commanded OFF? | -- | |||||||||
8 | Inspect circuit 687 (WHT) of the engine wiring harness for an open, short to ground or short to power. Repair the circuit if necessary. Refer to General Electrical Diagnosis Procedures in Wiring Systems. Did you find an open, short to ground or short to power condition? | -- | ||||||||
Is the resistance within the specified range? | 20-32 ohms | |||||||||
10 | Replace the PCM. Refer to PCM Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||||
11 |
Is the resistance within the specified range? | 20-32 ohms | ||||||||
12 | Measure the resistance between terminal S and ground, and between terminal E and ground. Are both measurements greater than the specified value? | 250 K ohms | Go to Diagnostic Aids | |||||||
13 |
Are both measurements greater than the specified value? | 250 K ohms | ||||||||
14 | Replace the A/T Wiring Harness Assembly. Refer to TCC PWM Solenoid, TCC Solenoid, and Wiring Harness Replacement. Is the replacement complete? | -- | -- | |||||||
15 | Replace the 3-2 SS Valve Assembly. Refer to Control and Shift Solenoids Replacement. Is the replacement complete? | -- | -- | |||||||
16 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
DTC P0785 3-2 Shift Solenoid Circuit Electrical 4.3L
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 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 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 5 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 VCM commands the solenoid ON and the voltage input remains high (B+). |
| - | The VCM commands the solenoid OFF and the voltage input remains low (0 volts). |
Action Taken When the DTC Sets
| • | The VCM illuminates the Malfunction Indicator Lamp (MIL). |
| • | The VCM commands a soft landing to third gear. |
| • | The VCM commands maximum line pressure. |
| • | The VCM inhibits TCC engagement. |
| • | The VCM inhibits 4th gear if the transmission is in hot mode. |
| • | The VCM freezes shift adapts from being updated. |
| • | DTC P0785 stores in VCM history. |
Conditions for Clearing the MIL/DTC
| • | The VCM turns OFF the MIL after three consecutive trips without a failure reported. |
| • | A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM. |
Diagnostic Aids
| • | Inspect the wiring at the VCM, the transmission connector and all other circuit connecting points 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 |
| - | Moisture intrusion |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change. |
Test Description
The item numbers below refer to the step numbers on the diagnostic table.
-
This step tests the ability of the VCM to control the solenoid.
-
This step tests for voltage to the solenoid.
-
This step tests the ability of the VCM and the wiring to control the ground circuit.
-
This step measures the resistance of the Automatic Transmission Wiring Harness Assembly (A/T Wiring Harness Assembly), and the 3-2 SS Valve Assembly.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Were you sent here from the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls | |||||||
2 |
Important: Before clearing the DTC(s), use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the VCM. Are DTCs P0740, P0753, P0758 and P1860 also set? | -- | ||||||||
3 |
Did you find a short to ground condition? | -- | ||||||||
Using the transmission output control function on the scan tool, command the 3-2 SS Valve Assembly. ON and OFF three times, while listening to the bottom of the transmission pan (a stethoscope may be necessary). Does the solenoid click when commanded? | -- | Go to Diagnostic Aids | ||||||||
Does the test lamp illuminate? | -- | |||||||||
6 | Repair the open or short to ground in ignition feed circuit 1020 (PNK) to the 3-2 SS Valve Assembly. Refer to General Electrical Diagnosis Procedures. Did you find and correct an open or short to ground condition? | -- | -- | |||||||
Does the test lamp illuminate when you command the shift solenoid ON, and turn OFF when you command OFF? | -- | |||||||||
8 |
Refer to General Electrical Diagnosis Procedures. Did you find an open, short to ground or short to power condition? | -- | ||||||||
9 | Replace the VCM. Refer to VCM Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||||
Is the resistance within the specified range? | 20-32 ohms | |||||||||
11 |
Is the resistance within the specified range? | 20-32 ohms | ||||||||
12 |
Are both measurements greater than the specified value? | 250 K ohms | Go to Diagnostic Aids | |||||||
13 |
Are both readings greater than the specified value? | 250 K ohms | ||||||||
14 | Replace the A/T Wiring Harness Assembly. Refer to TCC PWM Solenoid, TCC Solenoid, and Wiring Harness Replacement. Is the replacement complete? | -- | -- | |||||||
15 | Replace the 3-2 Shift Solenoid Valve Assembly. Refer to Control and Shift Solenoids Replacement. Is the replacement complete? | -- | -- | |||||||
16 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
