M99 - Automatic Transmission
DTC P0776 or P0777
Diagnostic 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 Descriptor
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 (w/body and TCM) valve assembly and is not serviced separately. PC solenoid 2 controls transmission fluid pressure to the hybrid direct 2-3-4 clutch regulator valve. The TCM calculates gear ratio based on data from the drive motor 1 speed, drive motor 2 speed, and the output speed sensor (OSS). The TCM compares the known transmission gear ratio to a calculated gear ratio for each commanded gear. Depending one the commanded mode or gear, the clutch PC solenoid 2 controls fluid pressure to the following components:
In the ON position, PC solenoid 2 controls transmission fluid to the following components:
* EVT 1 mode, oil is supplied to drive motors 1 and 2 for cooling and the hybrid low, 1-2 clutch.
* EVT 2 mode, oil is supplied to drive motors 1 and 2 for cooling and the hybrid direct 2-3-4 clutch.
* Gear 1, oil is supplied to the hybrid low, 1-2 clutch and the 1-3 clutch.
In the ON position, PC solenoid 2 controls the transmission fluid to the following components:
* Gear 2, oil is supplied to the hybrid low 1-2 clutch and the hybrid direct 2-3-4 clutch.
* Gear 3, oil is supplied to the hybrid direct 2-3-4 clutch and the 1-3 clutch.
* Gear 4, oil is supplied to the hybrid direct 2-3-4 clutch and the 4th clutch.
Conditions for Running the DTC
* No DTCs P0722 or P0723.
* No IMS DTCs.
DTC P0776
* The transmission input shaft speed is greater than 60 RPM.
* Hybrid direct 2-3-4 clutch is commanded ON.
DTC P0777
* The transmission output shaft speed is greater than 200 RPM.
* Hybrid direct 2-3-4 clutch is commanded OFF.
Conditions for Setting the DTC
DTC P0776
The TCM detects an incorrect on-coming clutch gear ratio, or flare, when the C2 clutch is commanded ON for 0.5 seconds and the transmission input shaft speed is greater than 75 RPM from the anticipated input shaft speed.
DTC P0777
The TCM detects an incorrect off-going clutch gear ratio, or tie-up, when the C2 clutch is commanded OFF for 0.5 seconds and the transmission input shaft speed is greater than 40 RPM from the anticipated input shaft speed.
Action Taken When the DTC Sets
* DTCs P0776 and P0777 are Type B DTCs.
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
Conditions for Clearing the DTC
DTCs P0776 and P0777 are Type B DTCs.
Diagnostic Aids
When attempting to set transmission performance DTCs, observe the Freeze Frame and Failure Records to assist in duplicating the failure conditions.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views
Electrical Information Reference
* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs
* High Voltage Disabling
* High Voltage Enabling
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
* Scan Tool Output Controls (Scan Tool Output Controls)
* Scan Tool Data List (Scan Tool Data List)
* Scan Tool Data Definitions (Scan Tool Data Definitions)
Special Tools
DT-47825 Control Solenoid Test Plate
Circuit/System Verification
1. Perform the Transmission Fluid Check (Transmission Fluid Check) procedure.
2. Operate the vehicle in drive with the calculated throttle position greater than 15 percent to obtain 72 km/h (45 mph).
• If the DTC resets, go to Circuit/System Testing.
Circuit/System Testing
1. Perform the Line Pressure Check (Line Pressure Check) procedure.
• If the pressure is out of specification, correct this concern first.
2. Perform the Control Solenoid Valve and Transmission Control Module Assembly Cleaning (Control Solenoid Valve and TCM Assembly Solenoid Performance Test) and retest the DTC as outlined in the Circuit/System Verification steps.
• If the DTC resets, continue on with testing.
3. Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and TCM Assembly Solenoid Performance Test) .
• If a concern is found, repair or replace the control solenoid (w/body and TCM) valve assembly.
4. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test (Control Solenoid Valve and TCM Assembly Solenoid Performance Test) .
• If the solenoid is found to be leaking or stuck closed, replace the control solenoid (w/body and TCM) valve assembly.
5. Inspect the control valve lower body assembly for sticking valves, damage, scored bores, or debris.
• If a concern is found in the valve body, repair or replace the valve body as necessary.
6. Inspect the hybrid direct 2-3-4 clutch assembly for damage.
• If a concern is found in the hybrid direct 2-3-4 clutch assembly, repair or replace as necessary.
Component Testing
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Control valve body replacement. Refer to Control Valve Body Replacement (Control Valve Body Replacement) .
* Hybrid direct 2-3-4 clutch assembly repair or replace. Refer to Hybrid Direct, 2-3-4 Clutch Housing Overhaul (Overhaul) .
* Control solenoid (w/body and TCM) valve assembly replacement. Refer to Control Module References for replacement, setup, and programming.