P0777
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
- Pressure Control Solenoid Valve 2 Stuck Off
DTC P0777
- Pressure Control Solenoid Valve 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. PC solenoid 2 regulates transmission fluid pressure to the 3-5-R regulator valve which controls pressure to the 3-5-R 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.
* Engine speed is 400 RPM or greater for 5 seconds.
* Ignition voltage is 9.0 volts or greater.
* Transmission fluid temperature (TFT) is -7°C (19°F) or greater.
* Transmission output speed is 650 RPM or greater or the throttle position is 0.5 percent or greater.
* Throttle position signal is valid.
* High side driver (HSD) 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.
* Engine speed is 400 RPM or greater for 5 seconds.
* Ignition voltage is 9.0 volts or greater.
* TFT is -7°C (19°F) or greater.
* Transmission output shaft speed is 200 RPM or greater.
* Throttle position signal is valid.
* HSD is enabled.
Conditions for Setting the DTC
P0776
The TCM detects an incorrect on-coming clutch gear ratio, or flare, when the 3-5-R clutch is commanded ON for 4 seconds and the transmission input shaft speed is 400 RPM or greater from the anticipated input shaft speed. This must occur 3 times.
P0777
The TCM detects an incorrect off-going clutch gear ratio, or tie-up, when the 3-5-R clutch is commanded OFF for 1 second and the transmission input shaft speed is 400 RPM or less from the anticipated input shaft speed. This must occur 3 times.
Action Taken When the DTC Sets
P0776
* DTC P0776 is a Type A DTC.
* TCM commands maximum line pressure.
* TCM limits the transmission to reverse and 2nd gear.
* TCM freezes transmission adaptive functions.
* TCM inhibits TAP Up/TAP Down function.
* TCM inhibits manual shifting of forward gears.
P0777
* DTC P0777 is a Type A DTC.
* TCM commands maximum line pressure.
* TCM limits the transmission to reverse and 3rd gear.
* TCM freezes transmission adaptive functions.
* TCM inhibits TAP Up/TAP Down function.
* TCM inhibits manual shifting of forward gears.
Conditions for Clearing the DIC/DTC
DTCs P0776 and P0777 are Type A DTCs.
Reference Information
Schematic Reference
* Drive Range, Third Gear (Gen 1) Drive Range, Third Gear (Gen 1)
* Drive Range, Fifth Gear (Gen 1) Drive Range, Fifth Gear (Gen 1)
Description and Operation
* Transmission General Description Transmission General Description
* Transmission Component and System Description Transmission Component and System Description
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
Circuit/System Verification
Warning: Refer to Parking Brake and Drive Wheels Warning Parking Brake and Drive Wheels Warning.
Note: If other DTCs are set, diagnose those DTCs first.
1. Engine idling in Park, with parking brake applied and drive wheels chocked.
2. Verify the transmission fluid level and condition is correct. Refer to Transmission Fluid Level and Condition Check Testing and Inspection.
3. Verify the scan tool Transmission Fluid Pressure Switch 1 parameter displays the correct state for each gear range while placing the gear select lever in Park, Reverse, and Neutral range. Refer to Transmission Fluid Pressure Switch Logic Transmission Fluid Pressure Switch Logic.
• If the correct state for each gear range is not displayed
Refer to Circuit/System Testing.
• If the correct state for each gear range is displayed
4. Gear select lever in Drive range.
Note: Use Drive 1st - Engine Braking to determine expected 1st gear Transmission Fluid Pressure Switch parameter states.
5. Verify the scan tool Transmission Fluid Pressure Switch 1 parameter displays the correct state for each gear range while commanding the scan tool Shift Transmission Gear through all forward ranges. Refer to Transmission Fluid Pressure Switch Logic Transmission Fluid Pressure Switch Logic.
• If the correct state for each gear range is not displayed
Refer to Circuit/System Testing.
• If the correct state for each gear range is displayed
6. Ignition ON, engine OFF. Clear the TCM DTC information with a scan tool.
7. Perform the Road Test Initial Inspection and Diagnostic Overview.
8. Verify DTC P0776 or P0777 did not set.
• If a DTC sets
Refer to Circuit/System Testing.
• If a DTC does not set
9. 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.
10. Verify the DTC does not set.
• If the DTC sets
Refer to Circuit/System Testing.
• If the DTC does not set
11. All OK.
Circuit/System Testing
Note: You must perform the Circuit/System Verification first.
1. Engine idling at the normal operating temperature.
2. Verify the transmission line pressures are within range. Refer to Line Pressure Check Line Pressure Check and Solenoid Valve Pressure (Gen 1) Solenoid Valve Pressure (Gen 1).
• If the line pressures are not within the specified ranges
Refer to Fluid Pressure High or Low Fluid Pressure High or Low.
• If line pressures are within the specified ranges
3. Engine Idling, shift selector in the Drive position.
4. Verify the scan tool parameters listed below display the correct state for each gear range while each gear range while commanding the scan tool Shift Transmission Gear through all forward ranges. Refer to Transmission Fluid Pressure Switch Logic Transmission Fluid Pressure Switch Logic for the correct gear range states.
* Transmission Fluid Pressure Switch 1
* Transmission Fluid Pressure Switch 3
* Transmission Fluid Pressure Switch 4
* Transmission Fluid Pressure Switch 5
• If the correct state for each gear range is not displayed
1. Ignition OFF.
2. Remove the Control Valve Body. Refer to Control Valve Body Replacement Control Valve Body Replacement.
3. Verify the Control Valve Body is not contaminated with any debris and there is no damage or sticking valves, refer to Control Valve Body Cleaning and Inspection (Gen 1) 44. Control Valve Body Cleaning and Inspection (Gen 1).
• If there is contamination, damage, or sticking valves, repair or replace the control valve body as necessary.
• If there is no contamination, damage, or sticking valves, replace the Q8 Control Solenoid Valve Assembly.
• If the correct state for each gear range is displayed
5. Verify the conditions listed below do not exist. Carefully inspect each component for that condition. Repair or replace as necessary.
DTC P0776 or P0777 - 3-5-R and 4-5-6 Clutch Housing Assembly
3-5-R clutch backing plate retaining ring not seated, causing clutch pack over-travel.
DTC P0776 or P0777 - Torque Converter (w/Fluid Pump) Housing Assembly
Fluid pump housing/gear damaged/scored.
DTC P0776 or P0777 - Control Valve Body Assembly
* Actuator feed limit circuit supply fluid to solenoids restricted or not available - debris or sediment blockage.
* 3-5-R Regulator Valve stuck/sticking - debris, binding, damaged valve, or scored bore.
* Control valve body ball check valve not seating correctly - debris.
DTC P0776 - Channel Plate and Spacer Plate
Oil channels or orifices blocked by debris.
DTC P0776 or P0777 - Q8 Control Solenoid Valve Assembly
* Clutch Pressure Control Solenoid 2 stuck ON/OFF.
* O-ring seals leaking.
* Valve body filter plate assembly cracked, blocked, or damaged gasket seal.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Note: Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection.
* Refer to Control Module References Programming and Relearning for control solenoid valve assembly replacement, setup, and programming.
* Perform the Transmission Adaptive Values Learn Programming and Relearning following all transmission related repairs.
* Perform the:
- Internal Components Removal 8. Internal Components Removal
- 3-5-Reverse and 4-5-6 Clutch Housing Disassemble (6T40/45/50 - Gen 1) 21. 3-5-Reverse and 4-5-6 Clutch Housing Disassemble (6T40/45/50 - Gen 1)
- 3-5-Reverse and 4-5-6 Clutch Housing Assemble (6T40/45/50 - Gen 1) 22. 3-5-Reverse and 4-5-6 Clutch Housing Assemble (6T40/45/50 - Gen 1)
- 3-5-Reverse and 4-5-6 Clutch Housing, and Input, Reaction, and Output Carrier Installation 24. 3-5-Reverse and 4-5-6 Clutch Housing, and Input, Reaction, and Output Carrier Installation