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DTC P0776 or P0777

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 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. Pressure control solenoid 2 regulates the transmission fluid pressure to 3-5-reverse clutch's regulator valve that controls the 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.

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 . 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 you complete the steps described above, check the diagnostic trouble code is not reset by driving the vehicle according to the conditions for running diagnostic trouble codes (DTC). You can also drive the vehicle according to the conditions you see in 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 . Check that the transmission's line pressure gauge is within the range specified in the table Line PC-solenoid valve pressure. Refer to Solenoid Valve Pressure .

2. If not within the specified ranges, refer to 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 Test of the control solenoid valve assembly and the transmission control module's solenoid performance . 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.


DTCs Component Condition
P0776 P0777 Upper Control Valve Body Assembly (349) 3-5-R regulator valve (336) stuck/sticking - debris, binding, damaged valve, or scored bore
P0776 Lower Control Valve Body Assembly (374)
• Actuator feed limit circuit supply fluid to solenoid restricted or not available - debris, stuck limit valve (362) or sediment blockage

• 3-5-R clutch boost valve (364) - binding or scored bore - can cause harsh shifts


P0776 P0777 Q8 Control Solenoid Valve Assembly
• Clutch pressure control solenoid 2 stuck On or stuck Off

• Control solenoid valve filter plate assembly, blocked or damaged gasket seal


P0776 P0777 A/Trans Fluid Pump (203)
• Fluid pump housing vanes/rotor/slide damaged/scored

• A/Trans pump fluid outlet seal assembly (57) damaged/leaking


P0776 A/Trans Fluid Filter Assembly (201) Oil filter (201) or filter seal (202) loose or damaged
P0776 Transmission Cooling/Lubrication
• Restriction/leak in oil to air (OAC) cooler/radiator

• Restricted/leaking/kinked/damaged transmission oil cooler lines

• Restriction/leak in transmission fluid pump assembly


P0776 Torque Converter Assembly (27) Torque converter overstressed due to high temperature, fluid boiled out
P0776 Automatic Transmission Fluid Filter Assembly (201) Oil filter (201) or filter seal (202) loose, plugged, or damaged
P0776 4-5-6 and 3-5-R Clutch Housing Assembly
• 3-5-R clutch backing plate retaining ring not seated or wave plate broken

• Torn, cut, or rolled 3-5-R piston seal (417)

• Inner/outer seal damaged

• Dam pressure too high


P0776 A/Trans Case Cover (403) Blow off regulator ball stuck.
P0776 P0777 Input shaft support 3-5-R and 4-5-6 clutch fluid seal rings (404) damaged, worn, or leaking


Repair Instructions

Note
• Perform the Resetting of the transmission's adaption after all transmission repairs.

• Before replacing the TCM, perform the 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