6L50/6L80/6L90 - Automatic Transmission
DTC P0973 or P0974
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0973
- Shift Solenoid (SS) 1 Control Circuit Low Voltage
DTC P0974
- Shift Solenoid (SS) 1 Control Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The shift solenoid (SS) 1 is part of the control solenoid valve assembly which has no serviceable parts. SS 1 is a normally closed (NC) ON/OFF solenoid and is controlled by the TCM through a low side driver. When the SS 1 is energized (ON), SS 1 fluid pressure is directed to the clutch select valve 2. Power to the SS 1 is supplied by the TCM through a high side driver (HSD). The HSD protects the circuit and components from excessive current flow. If excessive current flow is detected, the HSD will turn OFF. When the fault is corrected, the HSD will reset.
Conditions for Running the DTC
P0973 or P0974
* DTCs P0973 or P0974 have not set this ignition.
* The ignition voltage is 8.6 volts or greater.
* The engine speed is 500 RPM or greater for 5 seconds.
Conditions for Setting the DTC
P0973
The control solenoid valve assembly detects an internal low voltage electrical malfunction of the SS 1 control circuit when the SS 1 is commanded OFF for 2 seconds.
P0974
The control solenoid valve assembly detects an internal high voltage electrical malfunction of the SS 1 control circuit when the SS 1 is commanded ON for 2 seconds.
Action Taken When the DTC Sets
P0973
* DTC P0973 is a Type A DTC.
* The TCM defaults the transmission to 2nd gear or reverse gear.
* The TCM forces the torque converter clutch (TCC) OFF.
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
* The TCM enables Torque Management.
* The TCM inhibits TAP function.
* The TCM inhibits manual shifting of forward gears.
P0974
* DTC P0974 is a Type B DTC.
* The TCM inhibits 1st gear.
Conditions for Clearing the DIC/DTC
* DTC P0973 is a Type A DTC.
* DTC P0974 is a Type B DTC.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (6L45/6L50/6L80/6L90 - Automatic Transmission)
Connector End View Reference
* Component Connector End Views (Connector End Views By Name)
* Inline Harness Connector End Views (Connector End Views By Number)
Description and Operation
* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)
* Electronic Component Description (Electronic Component Description)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
DT-47825-10 - Jumper Harness
Circuit/System Verification
1. Operate the vehicle in 2nd gear long enough to ensure at least a 3°C (5°F) rise in TCM temperature.
2. Place the gear selector in Reverse for 5 seconds and then idle the vehicle in Park for 5 seconds. Verify with a scan tool the following test status parameters displays OK:
* Shift Solenoid Valve 1 Control Circuit High Voltage Test Status
* Shift Solenoid Valve 1 Control Circuit Open Test Status
* Shift Solenoid Valve 1 Control Circuit Low Voltage Test Status
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Note: You must perform the Circuit/System Verification first.
1. Ignition OFF, remove the Q8 control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement (6L45/6L50/6L80/6L90 - Automatic Transmission).
2. Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection).
3. Place the Q8 control solenoid valve assembly on a clean work surface near the transmission assembly.
4. Connect DT-47825-10 - jumper harness between the vehicle wire harness electrical connector, and the Q8 control solenoid valve assembly electrical connector.
5. Ignition ON, verify with a scan tool the following test status parameters display OK:
* Shift Solenoid Valve 1 Control Circuit High Voltage Test Status
* Shift Solenoid Valve 1 Control Circuit Open Test Status
* Shift Solenoid Valve 1 Control Circuit Low Voltage Test Status
• If any test status parameter displays Fault or Malfunction, replace the Q8 control solenoid valve assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Perform the Service Fast Learn Adapts (Programming and Relearning) following all transmission related repairs.
* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection).
* Control Module References (Programming and Relearning) for control solenoid valve assembly replacement, setup, and programming.