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 solenoid valve 2 is part of the control solenoid valve assembly, which has no serviceable parts. The pressure control solenoid valve 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 calculates gear ratio based on the RPM signals from the input speed sensor (ISS) and the output speed sensor (OSS). The Transmission Control Module compares the expected transmission gear ratio to the calculated gear ratio for each commanded gear.
Conditions for Running the DTC
P0776
* TCM DTC P0716, P0717, P0722, P0723, or P182E is not set.
* ECM 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, or P042E is not set.
* The accelerator pedal position is 0.5 percent or greater.
* The output speed is 16 RPM or greater.
* The ignition voltage is between 8.6-32 V.
* The engine speed is between 400-7500 RPM for 5 seconds.
* The transmission temperature is -6.6°C (20°F) or greater.
* The throttle position signal is valid.
* High side driver (HSD) is enabled.
* The PC solenoid 2 is commanded ON, applying the 3-5-R clutch.
P0777
* TCM DTC P0716, P0717, P0722, P0723, or P182E is not set.
* ECM 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, or P042E is not set.
* The accelerator pedal position is 0.5 percent or greater.
* The output speed is 16 RPM or greater.
* The ignition voltage is between 8.6-32 V.
* The engine speed is between 400-7500 RPM for 5 seconds.
* The transmission temperature is -6.6°C (20°F) or greater.
* The throttle position signal is valid.
* 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 Transmission Control Module 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 Transmission Control Module has detected an incorrect gear ratio change when the 3-5-R clutch is commanded OFF during a shift or when 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
Schematic Reference
Automatic Transmission Controls Schematics Electrical Diagrams
Connector End View Reference
* Component Connector End Views 5 Bow Lowered Switch (CM7)
* Inline Harness Connector End Views X102
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 Control Module References 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 position, 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 Transmission Fluid Level and Condition Check.
3. Ignition ON, clear the Transmission Control Module DTCs with a scan tool.
4. Verify the transmission operation performs as indicated in the road test instructions and DTCs P0776 or P0777 did not set. Refer to Road Test Initial Inspection and Diagnostic Overview.
• If DTCs P0776 or P0777 are set
Refer to Circuit/System Testing.
• If DTCs P0776 or P0777 did not set
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observe from the Freeze Frame/Failure Records data.
6. Verify the DTC does not set.
• If the DTC sets
Refer to Circuit/System Testing.
• If the DTC does not set
7. All OK.
Circuit/System Testing
Note: You must perform the Circuit/System Verification first.
1. Verify the transmission line pressures are within the specified ranges. Refer to Line Pressure Check Line Pressure Check.
• If fluid pressures are not within the specified ranges
Refer to Fluid Pressure High or Low Fluid Pressure High or Low.
• If fluid pressures are within the specified ranges
2. Ignition OFF, remove the Q8 Control Solenoid Valve Assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement Service and Repair.
3. Verify a pressure change occurs for each solenoid when performing the solenoid test. Refer to Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test.
• If a pressure change does not occur for each solenoid
Replace the Q8 Control Solenoid Valve Assembly.
• If a pressure change does occur for each solenoid
4. Very the conditions listed below do not exist. Carefully inspect each component for that condition. Repair or replace as necessary.
P0776 - Control Valve Upper Body Assembly (304)
3-5-R Regulator Valve (336) stuck/sticking - debris, binding, damaged valve, or scored bore.
P0776 - Control Valve Upper Body Assembly (304)
B-2-6 Regulator Valve (334) stuck/sticking - debris, binding, damaged valve, or scored bore.
P0776 or P0777 - Q8 Control Solenoid Valve Assembly (314)
* O-ring seals leaking.
* Valve body filter plate assembly cracked, blocked or damaged gasket seal.
P0776 or P0777 - Control Valve Upper Body Assembly (304)
* Actuator feed limit circuit supply fluid to solenoids restricted or not available, debris or sediment blockage.
* B-R-1/4-5-6 clutch regulator valve (327) not in the applied position - debris, binding, damaged valve, or scored bore.
* 4-5-6 clutch boost valve (329) not exhausting - debris, binding, damaged valve, or scored bore.
P0776 or P0777 - Torque Converter (w/Fluid Pump) Housing Assembly (2)
Fluid pump housing vanes/rotor/slide damaged/scored.
P0776 or P0777 - A/Trans Fluid Pump Cover Assembly (219)
Isolator valve (236) stuck/sticking - debris, binding, damaged valve, or scored bore.
P0776 - 1-2-3-4 and 3-5-R Clutch Housing Assembly (51)
3-5-R clutch backing plate retaining ring (400) not seated.
P0776 or P0777 - 1-2-3-4 and 3-5-R Clutch Housing Assembly (51)
1-2-3-4 clutch backing plate retaining ring (429) not seated, causing clutch pack/piston over travel.
P0776 - 4-5-6 Hub/ Shaft Assembly (58)
4-5-6 Hub/Shaft - broken hub weld.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Perform the Reset Transmission Adapts Reset Procedure following all transmission related repairs.
* Refer to Control Module References Control Module References for control solenoid valve assembly replacement, programming, and setup.