Circuit Description
The 1-2 shift solenoid (SS) valve controls transmission fluid pressure acting on the 1-2 and 2-3 shift valves to position the valves for the appropriate gear. The 1-2 SS valve is a normally open exhaust valve located on the control valve body. The transmission control module (TCM) provides voltage to the pressure control solenoid, the shift solenoids, and the TCC PWM solenoid through two separate solid-state devices called high side drivers (HSD) - HSD1 and HSD2. HSD1 provides electrical power to the pressure control solenoid. HSD2 provides electrical power to the shift solenoids, and the torque converter clutch pulse width modulated (TCC PWM) solenoid. The TCM then commands the solenoid ON or OFF by also providing a ground path. When the 1-2 SS valve is commanded ON, the TCM senses low voltage. When the 1-2 SS valve is commanded OFF, the TCM senses high voltage.
If the TCM detects a continuous short to voltage in the 1-2 SS valve circuit, DTC P0974 sets. DTC P0974 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0974 1-2 Shift Solenoid (SS) Control Circuit High Voltage
Conditions for Running the DTC
| • | The engine is running for 5 seconds and not in fuel cut-off. |
| • | The TCM commands the 1-2 SS valve ON. |
Conditions for Setting the DTC
The 1-2 SS valve feedback circuit indicates a continuous short to voltage for 4.4 seconds.
Action Taken When the DTC Sets
| • | The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | The TCM commands maximum line pressure. |
| • | The TCM freezes 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 Records. |
| • | The TCM stores DTC P0974 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.
-
This step tests the TCM and the wiring to the transmission.
-
This step verifies that the circuit has the correct resistance.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Important: Before 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 both the ECM and the TCM. Did DTC P0974 reset? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
Is the test lamp ON? | -- | Go to Step 4 | Go to Step 5 | |
4 | Test the control circuit of the 1-2 SS valve for a short to voltage between the TCM connector C2 and the AT inline 20-way connector. Refer to Testing for a Short to Voltage and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
Is the resistance within the specified range? | 19-31 ohms | Go to Step 7 | Go to Step 6 | |
6 |
Is the resistance less than the specified value? | 100 ohms | Go to Step 8 | Go to Step 9 |
7 | Measure the resistance between the 1-2 SS valve control circuit and all other terminals, except the 2-3 SS valve control circuit, the TCC PWM solenoid valve control circuit, and the ignition 1 voltage circuit of the J 44152 . Refer to Automatic Transmission Inline 20-Way Connector End View . Is the resistance less than the specified value? | 100 ohms | Go to Step 8 | Go to Testing for Intermittent Conditions and Poor Connections |
8 | Replace the automatic transmission wiring harness. Refer to Wiring Harness Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
9 | Replace the 1-2 SS valve. Refer to Control Valve Body Disassemble . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 | Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 11 | -- |
11 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 12 | Go to Step 2 |
12 | 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? | -- | System OK |
