P0777
DTC P0776 or P0777Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0776
Pressure Control Solenoid 2 Stuck Off
DTC P0777
Pressure Control Solenoid 2 Stuck On
Circuit/System Description
The clutch pressure control (PC) solenoid 2 is part of the control solenoid valve assembly, which has no serviceable components. The PC solenoid 2 regulates transmission fluid pressure to the 3-5-Reverse clutch regulator valve which controls pressure to the 3-5-Reverse clutch. The transmission control module (TCM) calculates gear ratio based on the RPM signals from the input speed sensor (ISS) and the output speed sensor (OSS). The TCM compares the expected transmission gear ratio to the calculated gear ratio for each commanded gear.
Conditions for Running the DTC
P0776
- DTC P0101, P0102, P0103, P0106, P0107, P0108, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0401, P042E, P0716, P0717, P0722, P0723, or P182E is not set.
- The ignition voltage is 8.6 volts or greater.
- The engine speed is 400 RPM or greater for 5.0 seconds.
- The transmission fluid temperature (TFT) is -7° C (19° F) or greater.
- The transmission output speed is 16 RPM or greater, or the throttle position is 0.5 percent or greater.
- The throttle position signal is valid.
- The high side driver is enabled.
P0777
- DTC P0101, P0102, P0103, P0106, P0107, P0108, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0401, P042E, P0716, P0717, P0722, P0723, or P182E is not set.
- The ignition voltage is 8.6 volts or greater.
- The engine speed is 400 RPM or greater for 5.0 seconds.
- The TFT is -7° C (19° F) or greater.
- The engine torque is 20 Nm (15 lb ft) or higher.
- The transmission input speed is 200 RPM or greater.
- The commanded gear is not 1st range.
- The transmission output speed is 16 RPM or greater, or the throttle position is 0.5 percent or greater.
- The throttle position signal is valid.
- The high side driver is enabled.
Conditions for Setting the DTC
P0776
The TCM has detected an incorrect gear ratio or neutral condition when the 3-5-Reverse clutch is commanded ON. This condition must occur 3 times.
P0777
The TCM has detected an incorrect gear ratio change when the 3-5-Reverse clutch is commanded OFF during a shift or when 3rd ratio is detected in 1st gear. This condition must occur 3 times.
Action Taken When the DTC Sets
P0776
- DTC P0776 is a Type A DTC.
- The TCM commands maximum line pressure.
- The TCM inhibits Tap Up/Down function.
- The TCM freezes transmission adaptive functions.
- The TCM inhibits manual shifting of forward gears.
- The TCM limits the transmission to Reverse, 2nd, and 4th gear operation.
P0777
- DTC P0777 is a Type A DTC.
- The TCM commands maximum line pressure.
- The TCM inhibits Tap Up/Down function.
- The TCM inhibits manual shifting of forward gears.
- The TCM freezes transmission adaptive functions.
- The TCM limits the transmission to 3rd gear and Reverse operation.
Conditions for Clearing the DIC/DTC
DTCs P0776 and P0777 are Type A DTCs.
Diagnostic Aids
Before performing a road test, configure and setup the scan tool for snapshot mode. This allows you to display, monitor, and verify multiple transmission data parameters at one time, after the road test.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
- Component Connector End Views
- Inline Harness Connector End Views
Description and Operation
Transmission General Description
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References
Circuit/System Verification
1. Engine idling in Park, with parking brake applied and drive wheels chocked.
2. Perform the Transmission Fluid Level and Condition Check to verify correct fluid level and condition. Component Tests and General Diagnostics
3. Monitor the Transmission Fluid Pressure Switch 1 parameter with a scan tool. Place the gear select lever in Park, Reverse, and Neutral range. Verify the Transmission Fluid Pressure Switch 1 parameter states are correct for Park, Reverse, and Neutral. Refer to Transmission Fluid Pressure Switch Logic.
4. Place the gear select lever in Drive range. Command the shift transmission with a scan tool through all forward ranges. Verify the Transmission Fluid Pressure Switch 1 parameter states are correct for all forward ranges. Refer to Transmission Fluid Pressure Switch Logic.
5. Engine idling in Park, verify with a scan tool the Transmission ISS/OSS Supply Voltage parameter displays OK.
6. Engine idling in Park. Observe the Transmission ISS parameter on the scan tool, while varying the engine speed. The Transmission ISS parameter should vary with engine speed and not drop out.
7. Operate the vehicle at 16-32 km/h (10-20 mph) while observing the Transmission OSS parameter on the scan tool. The Transmission OSS parameter should vary with the vehicle speed and not drop out.
8. Note
Perform a scan tool snapshot, during the road test.
Perform the road test. Initial Inspection and Diagnostic Overview Verify the transmission operation performs as indicated, in the road test instructions.
9. Review the scan tool snapshot data. Verify the following transmission data parameters display the correct values for each gear range:
- Transmission ISS
- Transmission OSS
- Pressure Control Solenoid Valve 2 Pressure Command
- Transmission Fluid Pressure Switch 1
10. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the conditions for running fault codes (DTC). You may also operate the vehicle within the conditions you observe from the freeze frame/failure records. If the vehicle passes the circuit/system verification procedure, then stop. Do not perform the circuit/system test or component test as this may result in unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections.
Circuit/System Testing
1. Note
You must perform the Circuit/System Verification first.
Perform the Line Pressure Check. Component Tests and General Diagnostics Check that the transmission's line pressure gauge is within the range specified in the table Line PC-solenoid valve pressure. See Solenoid valve pressure.
2. If not within the specified ranges, refer to Fluid Pressure High or Low. Fluid Pressure High or Low
3. Remove control solenoid valve assembly Q8 with ignition OFF. See Replacing control solenoid valve assembly and transmission control module.
4. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test. Component Tests and General Diagnostics A pressure change should occur for each solenoid.
5. If the Q8 control solenoid valve assembly does not pass the performance test, replace the Q8 control solenoid valve assembly.
6. Listed in the table below, are conditions for each component that could set DTC P0776 or P0777. Carefully inspect each component for that condition. Repair or replace as necessary.
Repair Instructions
Note
- Perform the Transmission Adaptive Values Learn following all transmission related repairs. Programming and Relearning
- Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection. Control Solenoid Valve and Transmission Control Module Assembly Inspection
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Control Valve Lower Body and Upper Body Replacement
- Low and Reverse Clutch and 1-2-3-4 Clutch Plate Removal
- Control Module References for control solenoid valve assembly replacement, setup, and programming