Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category |
Circuit Description
The 1-2 shift solenoid (SS) valve controls the fluid flow acting on the 1-2 and 3-4 shift valves. The solenoid is a normally-open exhaust valve. With the 2-3 SS valve, the 1-2 SS valve allows 4 different shifting combinations. The solenoid attaches to the control valve body within the transmission. The 1-2 SS valve receives ignition voltage through the ignition 1 voltage circuit. The transmission control module (TCM) controls the solenoid by providing the ground path on the 1-2 SS valve control circuit.
When the TCM detects a continuous short to voltage in the 1-2 shift solenoid valve control circuit, then DTC P0974 sets. DTC P0974 is a type A 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 system voltage is 8-18 volts. |
| • | The engine speed is 500 RPM for 5 seconds. |
Conditions for Setting the DTC
DTC P0974 sets if the TCM commands the solenoid ON and the voltage feedback remains high B+.
Action Taken When the DTC Sets
| • | The TCM requests the 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 TCM inhibits TCC engaugement. |
| • | At the time of the first failure, the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record. |
| • | At the time of the second failure, the ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame. |
| • | The TCM stores DTC P0974 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met. |
Conditions for Clearing the DTC
| • | The ECM turns OFF the MIL after the 4th consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | A scan tool can clear the DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM. |
Step | Action | Values | 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 the transmission control module (TCM). Does the 1-2 Sol. CKT status parameter display OK? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | ||||||
3 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 4 | ||||||
4 |
Does the resistance measure less than the specified value? | 20 Ω | Go to Step 5 | Go to Step 7 | ||||||
5 |
Does the resistance measure less than the specified value? | 20 Ω | Go to Step 8 | Go to Step 7 | ||||||
6 | Test the control circuit of the 1-2 SS valve for a short to voltage between the TCM and the A/T inline 20-way connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 | ||||||
7 | Replace the A/T internal wiring harness. Refer to Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||
8 | Replace the 1-2 SS valve. Refer to Control and Shift Solenoids Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||
9 | Replace the TCM. Refer to Control Module References . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||
10 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 11 | Go to Step 2 | ||||||
11 | 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 |
