Circuit Description
The 1-2 shift solenoid (SS) valve controls transmission fluid pressure acting on the 1-2 and 3-4 shift valves to position the valves for the appropriate gear. The 1-2 SS valve is a normally open exhaust valve located on the lower control valve body. Ignition voltage is supplied to the solenoid. The powertrain control module (PCM) commands the solenoid ON or OFF by providing a ground path. When the 1-2 SS valve is commanded ON, the PCM senses low voltage. When the 1-2 SS valve is commanded OFF, the PCM senses high voltage.
If the PCM detects a continuous short to voltage in the 1-2 SS valve circuit, then 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 run time is greater than 5 seconds. |
| • | The PCM 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 4.3 seconds.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | The PCM commands maximum line pressure. |
| • | The PCM inhibits 4th gear when in hot mode. |
| • | The PCM freezes transmission adaptive functions. |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records. |
| • | The PCM stores DTC P0974 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool can clear the MIL/DTC. |
| • | The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the PCM and the wiring to the transmission.
-
This step verifies that the circuit has the correct resistance.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
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 the PCM. Does the scan tool display indicate a short to voltage? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
Does the test lamp illuminate? | -- | 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 PCM and the AT inline 20-way connector. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
Refer to Automatic Transmission Inline 20-Way Connector End View . Is the resistance within the specified range? | 20-40 ohms | Go to Step 7 | Go to Step 6 | |
6 |
Does the resistance measure 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 1-2 SS valve ignition voltage circuit, of the J 44152 . Refer to Automatic Transmission Inline 20-Way Connector End View . Does the resistance measure less than the specified value? | 100 ohms | Go to Step 8 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
8 | Replace the automatic transmission wiring harness. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
9 | Replace the 1-2 SS valve. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems 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? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
