P0776
DTC P0776 or P0777
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
- Clutch Pressure Control (PC) Solenoid 2 - Stuck Off
DTC P0777
- Clutch Pressure Control (PC) 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 parts. 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 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
* No other ECM or TCM DTCs are set.
* The accelerator pedal position is 0.5 percent or greater.
* The transmission output speed is 16 RPM or greater.
* The ignition voltage is 8.6 volts or greater.
* The engine speed is 400 RPM or greater for 5 seconds.
* The transmission temperature is -6.6°C (20°F) or greater.
* The throttle position signal is valid.
* The high side diver (HSD) is enabled.
* The PC solenoid 2 is commanded ON, applying the 3-5-R clutch.
P0777
* No other ECM or TCM DTCs are set.
* The accelerator pedal position is 0.5 percent or greater.
* The transmission output speed is 16 RPM or greater.
* The ignition voltage is 8.6 volts or greater.
* The engine speed is 400 RPM or greater for 5 seconds.
* The transmission temperature is -6.6°C (20°F) or greater.
* The throttle position signal is valid.
* The high side driver (HSD) is enabled.
* The PC solenoid 2 is commanded OFF, releasing the 3-5-R clutch.
Conditions for Setting the DTC
P0776
The TCM has detected an incorrect gear ratio or neutral condition when the 3-5-R clutch is commanded ON. This condition must occur 3 times.
P0777
The TCM has detected an incorrect gear ratio change when the 3-5-R clutch is commanded OFF during a shift or when the 3rd gear 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 Tow/Haul mode.
* The TCM freezes transmission adaptive functions.
* The TCM inhibits Tap Up/Down function.
* The TCM inhibits Manual Up/Down Shift with the shift selector.
* The TCM limits the transmission to Reverse gear, 2nd gear, and 4th gear operation. Once 2nd gear is obtained, the transmission will stay in 2nd gear.
P0777
* DTC P0777 is a Type A DTC.
* The TCM commands maximum line pressure.
* The TCM inhibits Tow/Haul mode.
* The TCM freezes transmission adaptive functions.
* The TCM inhibits Tap Up/Down function.
* The TCM inhibits Manual Up/Down Shift with the shift selector.
* The TCM limits the transmission to Reverse gear, and 3rd gear 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 will allow you to display, monitor, and verify multiple transmission data parameters at one time, after the road test.
Reference Information
Connector End View Reference
* Component Connector End Views (Connector End Views By Name)
* Inline Harness Connector End Views (Connector End Views By Number)
Description and Operation
* Electronic Component Description (Electronic Component Description)
* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)
* Park - Engine Running (Park - Engine Running)
* Reverse (Reverse)
* Neutral - Engine Running (Neutral - Engine Running)
* Drive Range, First Gear Engine Braking (First Gear Engine Braking)
* Drive Range, First Gear (First Gear)
* Drive Range, Second Gear (Second Gear)
* Drive Range, Third Gear (Third Gear)
* Drive Range, Third Gear Default (Third Gear Default)
* Drive Range - Fourth Gear (Fourth Gear)
* Drive Range, Fifth Gear (Fifth Gear)
* Drive Range, Fifth Gear Default (Fifth Gear Default)
* Drive Range, Sixth Gear (Sixth Gear)
* Fluid Passages (Fluid Passages)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
* DT-47825 - Control Solenoid Test Plate
* J 21867 - Pressure Gauge
For equivalent regional tools, refer to Special Tools (Tools and Equipment).
Circuit/System Verification
Note: If other DTCs are set, diagnose those DTCs first.
1. Engine idling in Park, with parking brake applied and drive wheels chocked.
2. Perform the Transmission Fluid Level and Condition Check (Transmission Fluid Level and Condition Check) to verify correct fluid level and condition.
3. Monitor the Transmission Fluid Pressure (TFP) switch 1 with a scan tool. Place the gear select lever in Park, Reverse, and Neutral range. Verify the TFP switch 1 parameter states are correct for Park, Reverse, and Neutral. Refer to Transmission Fluid Pressure Switch Logic (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 TFP switch 1 parameter states are correct for all forward ranges. Refer to Transmission Fluid Pressure Switch Logic (Transmission Fluid Pressure Switch Logic).
5. Engine idling in Park, verify with a scan tool the Transmission ISS/OSS supply voltage test status 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.
Note: Perform a scan tool snapshot, during the road test.
8. Perform the Road Test (Road Test). 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
* PC Solenoid 2
* TFP Switch 1
10. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions you observe from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, then STOP. Do not perform the Circuit/System Testing or Component Testing as this may result in an unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections).
Circuit/System Testing
Note: You must perform the Circuit/System Verification first.
1. Perform the Line Pressure Check (Line Pressure Check). Verify the transmission line pressures are within the specified ranges.
• If not within the specified ranges, refer to Fluid Pressure High or Low (Fluid Pressure High or Low).
2. Ignition OFF, remove the control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement (Service and Repair).
3. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test (Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test). Test all solenoids on the Q8 control solenoid valve assembly. A pressure change should occur for each solenoid valve.
• If the Q8 control solenoid valve assembly does not pass the performance test, replace the Q8 control solenoid valve assembly.
4. Listed in the chart 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
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Control solenoid valve assembly replacement. Refer to Control Module References (Programming and Relearning) for replacement, setup, and programming.
* Perform the Service Fast Learn Adapts (Programming and Relearning) following all transmission related repairs.