P0777
DTC P0776 or P0777
Diagnostic Instructions
* Perform theDiagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* ReviewStrategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0776
- Pressure Control (PC) Solenoid 2 - Stuck Off
DTC P0777
- Pressure Control (PC) Solenoid 2 - Stuck On
Circuit/System Description
The transmission has 2 pressure control solenoids that controls the flow of transmission fluid to engage clutches. The flow is directed through shift valves that allows it to engage different clutches. The vehicle speed sensor and automatic transmission turbine speed sensor contains a permanent magnet surrounded by a coil that gives off a continuous magnetic field. As the vehicle is driven, a speed sensor rotor located near the magnetic pickup of the speed sensor coil also rotates. This rotation produces a variable AC voltage signal. The frequencies of the signals are proportional to the transmission turbine and output speeds. The transmission control module (TCM) uses the signals to calculate the gear ratio. The TCM compares the computed ratio to the commanded gear ratio.
Conditions for Running the DTC
P0776
* Output speed is greater than 125 RPM.
* Turbine speed is greater than 60 RPM.
* Transmission is at normal operating temperature.
* DTCs P0716, P0717, P0721, P0722, P0877, and P0878 are not active.
P0777
* Output speed is greater than 200 RPM.
* Turbine speed is greater than 200 RPM.
* Transmission is at normal operating temperature.
* DTCs P0716, P0717, P0721, P0722, and P0877 are not active.
Conditions for Setting the DTC
P0776
This DTC sets during a shift when the calculated commanded gear ratio differs from the known commanded gear ratio for more than 2 seconds.
P0777
This DTC sets during a shift when the off going gear ratio remains the same even though it is commanded off.
Action Taken When the DTC Sets
P0776
* The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).
* If transmission was in a forward range, transmission will shift back to the previous range. If the transmission was in reverse or neutral, the transmission will shift to neutral.
* While diagnostic response is active, if shift selector is moved to neutral, the transmission will shift to neutral. If the transmission is shifted to reverse (R), the transmission will shift to reverse or neutral. If the shift selector is moved to a forward range and transmission is compromised by overspeeding or direction change, transmission shifts to neutral.
* DTC P0776 is stored in TCM history.
* The TCM inhibits torque converter clutch (TCC) engagement.
P0777
* The TCM requests the ECM to illuminate the MIL.
* If transmission was in a forward range, transmission will shift back to the previous range. If the transmission was in reverse or neutral, the transmission will shift to neutral.
* While diagnostic response is active, if shift selector is moved to neutral, the transmission will shift to neutral. If the transmission is shifted to R (reverse), the transmission will shift to reverse or neutral. If the shift selector is moved to a forward range and transmission is compromised by overspeeding or direction change, transmission shifts to neutral.
* DTC P0777 is stored in TCM history.
* The TCM inhibits TCC engagement.
Conditions for Clearing the DTC
DTCs P0776 and P0777 are Type A DTCs.
Diagnostic Aids
* You will have to drive the vehicle in order to experience a condition.
* DTC may indicate a component condition with piston seals, clutch plates, or solenoids.
* DTC may be caused by a faulty speed sensor signal.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
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 (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Inspect the transmission fluid level. Refer to Transmission Fluid Check (Transmission Fluid Check) .
2. Perform a road test. Refer to Road Test (Road Test Procedure) .
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 on the Freeze Frame/Failure Records data.
Circuit/System Testing
Note
You must perform the Circuit/System Verification first.
1. Perform a line pressure test. Refer to Line Pressure Check (Line Pressure Check) .
• If line pressure is low in all ranges, refer toLow Main Line Pressure in All Ranges (Low Main Line Pressure In All Ranges) .
• If line pressure is low in a specific range or ranges, refer toLow Main Line Pressure in Specific Ranges, Normal Pressure in Other Ranges (Low Main Line Pressure in Specific Ranges, Normal Pressure in Other Ranges) .
Warning
Chock the wheels to prevent the vehicle from moving. Failure to chock the wheels can cause personal injury when the electrical system is repaired.
2. Perform the clutch test. Refer to Clutch Test (Clutch Test) .
• If not the specified value, refer toExcessive Slippage and Clutch Chatter (Excessive Slippage and Clutch Chatter) .
3. If the above test is normal, refer toFunctional Test (Functional Test Procedure) .
Repair Instructions
Perform theDiagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Speed Sensor Replacement (Service and Repair)
* Control Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD) (Control Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD))Control Valve Solenoid Replacement (PCS1 and PCS2) (Control Valve Solenoid Replacement (PCS1 and PCS2))
* Control Valve Body Cleaning and Inspection (Overhaul)
Repair Verification
If another DTC is present, refer toDiagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) and perform the appropriate diagnostic procedure.