4L60-E/4L65-E/4L70-E - 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
- 1-2 Shift Solenoid (SS) Control Circuit Low Voltage
DTC P0974
- 1-2 Shift Solenoid (SS) Control Circuit High Voltage
Diagnostic Fault Information
Circuit/System 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 voltage circuit. The transmission control module (TCM) controls the solenoid by providing the ground path on the 1-2 SS valve control circuit.
Conditions for Running the DTC
* The engine speed is 500 RPM for 5 seconds.
* The 1-2 SS is commanded ON.
Conditions for Setting the DTC
P0973
Either one of the following conditions occurs for 4.3 seconds:
* The TCM detects an open in the 1-2 shift solenoid valve circuit when commanded ON.
* The TCM detects a short to ground in the 1-2 shift solenoid valve circuit when commanded ON.
P0974
If the TCM commands the solenoid ON and the voltage feedback remains high B+.
Action Taken When the DTC Sets
P0973
* P0973 is a Type B DTC.
* The TCC commands maximum line pressure.
* The TCM inhibits 3-2 shift until vehicle speed is less than 20 km/h (12 mph).
* The TCM freezes transmission adaptive functions.
P0974
* The TCC commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
Conditions for Clearing the DTC
DTCs P0973 and P0974 are Type B DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (4L60-E/4L65-E/4L70-E - Automatic Transmission)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Transmission General Information (Transmission General Information)
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
Transmission Control Module Scan Tool Information (4L60-E) (Transmission Control Module Scan Tool Information (4L60-E))Transmission Control Module Scan Tool Information (6L45/6L50/6L80/6L90) (Transmission Control Module Scan Tool Information (6L45/6L50/6L80/6L90))Transmission Control Module Scan Tool Information (2ML70) (Transmission Control Module Scan Tool Information (2ML70))Transmission Control Module Scan Tool Information (Allison) (Transmission Control Module Scan Tool Information (Allison))
Special Tools
* J 44152 Jumper Harness (20 Pins)
* J 45681 Jumper Harness
Circuit/System Verification
1. Ignition ON, engine OFF, observe the 1-2 Sol. CKT Status parameter while commanding the 1-2 SS ON and OFF with a scan tool. The reading should display OK or Indeterminate.
2. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Important: Additional DTCs may set when disconnecting the automatic transmission inline 20-way connector.
1. Ignition OFF, disconnect the AT inline 20-way connector at the transmission.
2. Install the J 45681 jumper harness, on the engine side of the AT inline 20-way connector.
3. Connect a test lamp between the control circuit terminal A and the ignition circuit terminal E.
4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal E and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
5. Command the 1-2 SS ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the TCM.
• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the TCM.
6. If all circuits test normal, test the automatic transmission internal wiring harness and the 1-2 shift solenoid.
Component Testing
1. Ignition OFF, disconnect the AT inline 20-way connector at the transmission.
2. Install the J 44152 jumper harness (20 pins), on the transmission side of the AT inline 20-way connector.
3. Test for 19-31 ohms of resistance between the control terminal A and the ignition terminal L of the transmission.
• If not within the specified range, test the circuits for a short to ground or an open/high resistance. If a circuit is shorted or open replace the internal transmission harness, if the circuits test normal, replace the 1-2 shift solenoid.
4. Test for infinite resistance between each terminal and the transmission housing/case.
• If not the specified value, test the circuits for a short to ground or an open/high resistance. If a circuit is shorted replace the internal transmission harness, if the circuits test normal, replace the 1-2 shift solenoid.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.
* Control and Shift Solenoids Replacement (4L60-E/4L65-E/4L70-E - Automatic Transmission)
* Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness (Service and Repair)
* Control Module References (Control Module References) for TCM replacement, setup and reprogramming