Automatic Transmission - MVA 4 Speed
DTC P0776 or P0778
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 P0776
- Shift Solenoid B Performance (Shift Solenoid Valve SL2)
DTC P0778
- Shift Solenoid B Electrical (Shift Solenoid Valve SL2)
Diagnostic Fault Information
Circuit/System Description
The powertrain control module (PCM) provides a B+ and control circuit to the shift solenoid valve SL2. The PCM uses signals from both vehicle speed sensors to detect the actual gear position, 1ST, 2ND, 3RD or 4TH gear. The PCM then compares the actual gear with the shift schedule stored in the PCM memory to detect electrical concerns with the PCM, shift solenoid, electrical circuits or with mechanical components of the transmission. When the gear position commanded by the PCM and the actual gear positions are not the same, the PCM illuminates the MIL and stores the DTC.
Conditions for Running the DTC
P0776 or P0778
The engine is running.
Conditions for Setting the DTC
P0776
The gear position commanded by the PCM and the actual gear position are not the same.
P0778
The PCM detects a short to ground or an open/high resistance on the B+ or control circuit of the shift solenoid valve SL2.
Action Taken When the DTC Sets
DTC P0776 and P0778 are type A DTCs.
Conditions for Clearing the DTC
DTC P0776 and P0778 are type A DTCs.
Diagnostic Aids
* The battery must be fully charged. Refer to Battery Inspection/Test (Battery Inspection/Test).
* All resistance tests are conducted with the component at 20°C (68°F).
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
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
Powertrain Control Module Scan Tool Information (Scan Tool Testing and Procedures) for scan tool information
Circuit/System Verification
Note: If other DTCs are set, diagnosis them first. Refer to Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle).
1. Operate the vehicle at less than 48 km/h (30 mph) with steady throttle input.
2. Command the transmission to shift up or shift down with a scan tool. The transmission should shift to the gear commanded by the scan tool.
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
1. Ignition OFF, disconnect the transmission harness connector.
2. Test for 5-6 ohm between the transmission component connector, terminal 4 and terminal 9.
• If not within the specified value, test the transmission internal wire harness for an open/high resistance. If the circuit tests normal, replace the shift solenoid valve SL2.
3. Test for greater than 10K ohm between the transmission component connector, terminal 4 and ground and also terminal 9 and ground.
• If less than the specified value, test the transmission internal wire harness for a short to ground. If the circuit tests normal, replace the shift solenoid valve.
4. Ignition OFF, connect the transmission harness connector.
5. Disconnect the PCM X2 harness connector.
6. Test for 5-6 ohm between the PCM X2 harness connector terminal 58 and terminal 59.
• If not within the specified value, test the shift solenoid valve, SL2, voltage circuit and the control circuit for an open/high resistance.
7. Test for greater than 10K ohm between the PCM X2 harness connector terminal 58 and ground.
• If less than the specified value, test the voltage circuit for a short to ground.
8. Test for greater than 10K ohm between the PCM X2 harness connector terminal 59 and ground.
• If less than the specified value, test the control circuit for a short to ground.
9. If all circuits test normal, replace the PCM.
Component Testing
1. Ignition OFF, remove the shift solenoid valve SL2.
2. Test for 5-6 ohm between terminals 1 and 2 of the shift solenoid valve SL2.
• If not within the specified value, replace the shift solenoid valve SL2.
3. Connect a 10 A fused jumper wire to terminal 1 and a non-fused jumper wire to terminal 2 of the shift solenoid valve SL2.
4. Momentary connect the other ends of the jumper wires to a 12 V battery. The solenoid should energize and make a click sound.
• If the solenoid does not energize and click, replace the shift solenoid valve SL2.
5. If all circuits test normal, refer to Symptoms - Automatic Transmission (Symptoms - Automatic Transmission).
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.
* Control Valve Body Replacement (MVA 4 Speed - Automatic Transmission)
* Powertrain Control Module Replacement (Service and Repair)
* Powertrain Control Module Programming and Setup (Testing and Inspection)