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 the ignition 0 voltage circuit. The powertrain control module (PCM) controls the solenoid by providing a ground path on the 3-2 shift solenoid valve control circuit. 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, short to ground or short to power in the 3-2 SS valve assembly circuit, then DTC P0785 sets. DTC P0785 is a type B DTC.
DTC P0785 sets if one of the following conditions occurs for 5 seconds:
Condition 1The PCM commands the solenoid ON and the voltage feedback remains high, B+.
Condition 2The PCM commands the solenoid OFF and the voltage feedback remains low, 0 volts.
The item 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 voltage to the solenoid.
This step tests the ability of the PCM and the wiring to control the ground circuit.
This step measures the resistance of the automatic transmission wiring harness assembly and the 3-2 SS valve assembly.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 4.8L, 5.3L and 6.0L |
2 |
ImportantBefore clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM. Are any of the following DTCs also set?
| -- | Go to Step 3 | Go to Step 4 |
3 | Inspect the IGN 0 fuse for an open. Refer to Circuit Protection - Fuses in Wiring Systems. Is the fuse open? | -- | Go to Step 12 | Go to Step 5 |
Use the scan tool in order to command the 3-2 shift solenoid (SS) valve assembly ON and OFF 3 times, while listening to the bottom of the transmission pan, a stethoscope may be necessary. Does the solenoid click when commanded? | -- | Go to Intermittent Conditions in Engine Controls - 4.8L, 5.3L and 6.0L | Go to Step 5 | |
Refer to Automatic Transmission Inline 20-Way Connector End View . Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 15 | |
Does the test lamp turn ON and OFF with each command? | -- | Go to Step 8 | Go to Step 7 | |
7 | Is the test lamp always ON? | -- | Go to Step 16 | Go to Step 17 |
Refer to Automatic Transmission Inline 20-Way Connector End View . Does the resistance measure within the specified range? | 20-32 ohms | Go to Step 9 | Go to Step 10 | |
9 |
Do both readings measure greater than the specified value? | 250 K ohms | Go to Intermittent Conditions in Engine Controls - 4.8L, 5.3L and 6.0L | Go to Step 11 |
10 |
Does the resistance measure within the specified range? | 20-32 ohms | Go to Step 18 | Go to Step 19 |
11 |
Do both readings measure greater than the specified value? | 250 K ohms | Go to Step 18 | Go to Step 19 |
12 |
ImportantThe condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics in Wiring Systems for complete circuit distribution. Test the ignition 0 voltage circuit of the 3-2 SS valve assembly for a short to ground between the fuse block and the AT inline 20-way connector. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 13 |
13 |
ImportantThe condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics in Wiring Systems for complete circuit distribution. Test the ignition 1 voltage circuit of the 3-2 SS valve assembly for a short to ground between the AT inline 20-way connector and the 3-2 SS valve assembly. Refer to Testing for Short to Ground in Wiring Systems. Did you find a short to ground condition? | -- | Go to Step 18 | Go to Step 14 |
14 |
Did you complete the replacement? | -- | Go to Step 21 | -- |
15 |
ImportantThe condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics in Wiring Systems for complete circuit distribution. Test the ignition 0 voltage circuit of the 3-2 SS valve assembly for an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | -- |
16 | Test the control circuit of the 3-2 SS valve assembly for a short to ground between the powertrain control module (PCM) connector C1 and the AT inline 20-way connector. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20 |
17 | Test the control circuit of the 3-2 SS valve assembly for an open or short to power between the PCM connector C1 and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20 |
18 | Replace the AT wiring harness assembly. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- |
19 | Replace the 3-2 SS valve assembly. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- |
20 | Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 4.8L, 5.3L and 6.0L. Did you complete the replacement? | -- | Go to Step 21 | -- |
21 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 22 | Go to Step 2 |
22 | With the scan tool, observe the stored information, capture info, and DTC Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 4.8L, 5.3L and 6.0L | System OK |