Diagnostic Instructions
DTC Descriptors
DTC P0979: 4-5 Shift Solenoid (SS) Control Circuit Low Voltage
DTC P0980: 4-5 Shift Solenoid (SS) Control Circuit High Voltage
Diagnostic Fault Information
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
|
Shift Solenoid (SS) C Control
| P0979
| P0979
| P0980
|
Circuit/System Description
The 4-5 shift solenoid valve is located in the control valve body of the transmission. The transmission control module (TCM) selects the required gear by turning the appropriate solenoid ON or OFF, enabling the transmission to shift.
The TCM provides voltage to the solenoid through high side driver 2 (HSD2). The TCM uses a second driver to control the solenoid ground circuit. The controlled ground driver reports feedback voltage to the TCM. When the TCM commands the 4-5 shift
solenoid valve ON, the voltage of the control circuit should be approximately 0 volts. When the TCM commands the 4-5 shift solenoid valve OFF, the voltage of the control circuit should be approximately system voltage.
Conditions for Running the DTC
| • | The engine run time is greater than 5 seconds. |
Conditions for Setting the DTC
P0979
The following conditions occur for 4.3 seconds:
| • | The TCM detects an open in the 4-5 shift solenoid valve circuit when HSD2 is commanded ON. |
| • | The TCM detects a short to ground in the 4-5 shift solenoid valve circuit when HSD2 is commanded OFF. |
P0980
The TCM detects a short to voltage in the 4-5 shift solenoid valve circuit for 4.3 seconds.
Action Taken When the DTC Sets
P0979
| • | DTC P0979 is a Type B DTC. |
| • | Powertrain braking is disabled at the time that the TCM first detects the failure, before the DTC sets. |
| • | The TCM turns off power to all solenoids. |
| • | The transmission will operate in fifth gear if the vehicle has successfully completed a 1-2 upshift in the current ignition cycle. If the vehicle has not completed a 1-2 upshift in the current ignition cycle, the transmission
will operate in fourth gear. |
| • | The TCM commands maximum line pressure. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM inhibits TAP shift. |
P0980
| • | DTC P0980 is a Type B DTC. |
| • | Powertrain braking is disabled at the time that the TCM first detects the failure, before the DTC sets. |
| • | The TCM turns off power to all solenoids. |
| • | The transmission will operate in fifth gear if the vehicle has successfully completed a 1-2 upshift in the current ignition cycle. If the vehicle has not completed a 1-2 upshift in the current ignition cycle, the transmission
will operate in fourth gear. |
| • | The TCM commands maximum line pressure. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM inhibits TAP shift. |
Conditions for Clearing the DTC
DTCs P0979 and P0980 are Type B DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Transmission General Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Transmission Control Module Scan Tool Information
Special Tools
J 45681
Jumper Harness
Circuit/System Verification
- Ignition ON, engine OFF, observe the 4-5 Sol. CKT Status parameter while commanding the 4-5 SS ON and OFF with a scan tool. The reading should display OK or Indeterminate.
- 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.
- Ignition OFF, disconnect the automatic transmission (AT) inline 20-way connector at the transmission.
- Install the
J 45681
on the engine side of the AT inline 20-way connector.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 17 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. |
- Connect a test lamp between the control circuit terminal 5 and the ignition circuit terminal 17.
- Command the 4-5 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. |
- If all circuits test normal, test the automatic transmission internal wiring harness and the 4-5 shift solenoid.
Component Testing
- Ignition OFF, disconnect the AT inline 20-way connector at the transmission.
- Install the
J 45681
on the transmission side of the AT inline 20-way connector.
- Test for 19-31 ohms of resistance between the control terminal 5 and the ignition terminal 17 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 4-5 shift solenoid. |
- 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 4-5 shift solenoid. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the repair.
