Circuit Description
The 2-3, 3-4 shift solenoid (SS) valve (S2) controls transmission fluid pressure acting on the M2 shift valve to position the valve for the appropriate gear. The 2-3, 3-4 SS valve (S2) is a normally open exhaust valve located on the front control valve body. The solenoid is case grounded. The output driver module (ODM), within the TCM, commands the solenoid ON or OFF by providing voltage. When the 2-3, 3-4 SS valve (S2) is commanded ON, the TCM senses high voltage. When the 2-3, 3-4 SS valve (S2) is commanded OFF, the TCM senses low voltage.
If the TCM detects a continuous open or short to voltage in the 2-3, 3-4 SS valve (S2) circuit, then DTC P0977 sets. DTC P0977 is a type A DTC.
Conditions for Running the DTC
| • | The system voltage is 8-18 volts. |
| • | The engine run time is greater than 5 seconds. |
| • | Trans. Protection Mode is OFF. |
| • | The TCM has commanded the 2-3, 3-4 SS valve OFF. |
Conditions for Setting the DTC
The 2-3, 3-4 SS valve (S2) feedback circuit indicates a continuous open or short to voltage for 0.5 seconds.
Action Taken When the DTC Sets
| • | The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL). |
| • | The TCM turns the Trans. Protection Mode ON. When the Trans. Protection Mode is ON, the following conditions occur: |
| - | The transmission will operate in 5th gear when the transmission is shifted into D or I range and 2nd gear when shifted into L range. |
| - | The line pressure is at maximum. |
| - | The torque converter clutch (TCC) is disabled. |
| - | The TCM freezes the transmission adaptive functions. |
| • | The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Record. |
| • | The TCM stores DTC P0977 in TCM history. |
Conditions for Clearing the MIL/DTC
| • | The ECM turns off the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | A scan tool can clear the MIL/DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | 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 - 3.0L (L81) |
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Eng./Trans. DTC Info function erases the Freeze Frame and Failure Records from the TCM. Is Shift Solenoid 2 CKT Status OK? | -- | Go to Intermittent Conditions in Engine Controls - 3.0L (L81) | Go to Step 3 |
3 |
Does the test lamp turn ON and OFF? | -- | Go to Step 4 | Go to Step 7 |
4 | Inspect for poor connections at the transmission AT inline 14-way connector. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 5 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 6 | |
6 |
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 |
7 |
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 |
8 | Inspect the TCM C2 connector for poor connections. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
9 | Replace the automatic transmission wiring harness. Refer to Wiring Harness Removal . Did you complete the replacement? | -- | Go to Step 12 | -- |
10 | Replace the 2-3, 3-4 SS valve (S2). Refer to Control Valve Body Assembly Disassemble . Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the TCM. Refer to Transmission Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
12 | Perform the following procedure in order to verify the repair:
Does the DTC reset? | -- | Go to Step 2 | Go to Step 13 |
13 | 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 to Engine Controls - 3.0L (L81) | System OK |
