6T30/6T40/6T45/6T50 (MH8, MH9) - Automatic Transmission (Gen 1)
DTC P0796 or P0797 (Gen 1)
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 P0796
- Pressure Control Solenoid Valve 3 Stuck Off
DTC P0797
- Pressure Control Solenoid Valve 3 Stuck On
Circuit/System Description
The clutch pressure control solenoid 3 is part of the control solenoid valve assembly which has no serviceable components. Pressure control solenoid 3 regulates transmission fluid pressure to the R1/4-5-6 regulator valve which controls pressure to the reverse and low clutch and the 4-5-6 clutch. The transmission control module (TCM) calculates gear ratio based on the speed signals from the automatic transmission input shaft speed (ISS) sensor and the output shaft speed (OSS) sensor. The TCM compares the expected transmission gear ratio to the calculated gear ratio for each commanded gear.
Conditions for Running the DTC
P0796
* 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 between 400-7500 RPM for 5 seconds.
* Transmission output speed is 650 RPM or greater or the throttle position is 0.5 percent or greater.
* Ignition voltage is between 9-32 V.
* Transmission fluid temperature is -7°C (19°F) or greater.
* High side driver is enabled.
* Throttle position signal is valid.
P0797
* 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 between 400-7500 RPM for 5 seconds.
* Transmission output speed is 650 RPM or greater, or the throttle position is 0.5 percent or greater.
* Throttle position signal is valid.
* Ignition voltage is between 9-32 V.
* Transmission fluid temperature is -7°C (19°F) or greater.
* High side driver is enabled.
* Transmission output shaft speed is 200 RPM or greater.
Conditions for Setting the DTC
P0796
TCM detects an incorrect on-coming clutch gear ratio (incorrect gear ratio), or flare.
P0797
TCM detects an incorrect off-going clutch gear ratio (incorrect gear ratio), or shift tie-up.
Action Taken When the DTC Sets
P0796
* DTC P0796 is a Type A DTC.
* TCM commands maximum line pressure.
* TCM freezes transmission adaptive functions.
* TCM inhibits TAP Up/TAP Down functions.
* TCM inhibits manual up, manual down shifts with the shift selector.
* TCM limits the transmission to reverse and 3rd gear.
P0797
* DTC P0797 is a Type A DTC.
* TCM commands maximum line pressure.
* TCM freezes transmission adaptive functions.
* TCM inhibits TAP Up/TAP Down functions.
* TCM inhibits manual up, manual down shifts with the shift selector.
* TCM limits the transmission to reverse and 4th gear.
Conditions for Clearing the DIC/DTC
DTCs P0796 and P0797 are Type A DTCs.
Diagnostic Aids
Before performing a road test, configure and setup the scan tool for snapshot mode. This allows you to monitor, display, 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 Fuel Pump and Level Sensor Assembly
* Inline Harness Connector End Views X100
Description and Operation
* Transmission General Description Transmission General Description
* Transmission Component and System Description Transmission Component and System Description
* Electronic Component Description Electronic Component Description
* Reverse (Gen 1) Reverse (Gen 1)Reverse (Gen 2) Reverse (Gen 2)
* Drive Range, First Gear Engine Braking (Gen 1) Drive Range, First Gear Engine Braking (Gen 1)Drive Range, First Gear Engine Braking (Gen 2) Drive Range, First Gear Engine Braking (Gen 2)
* Drive Range - Fourth Gear (Gen 1) Drive Range - Fourth Gear (Gen 1)Drive Range - Fourth Gear (Gen 2) Drive Range - Fourth Gear (Gen 2)
* Drive Range, Fifth Gear (Gen 1) Drive Range, Fifth Gear (Gen 1)Drive Range, Fifth Gear (Gen 2) Drive Range, Fifth Gear (Gen 2)
* Drive Range, Sixth Gear (Gen 1) Drive Range, Sixth Gear (Gen 1)Drive Range, Sixth Gear (Gen 2) Drive Range, Sixth Gear (Gen 2)
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
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 Transmission Fluid Level and Condition Check.
3. Verify the scan tool TFP Switch 5 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 TFP Switch 5 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 Road Test.
8. Verify DTC P0796 or P0797 did not set.
• If a DTC set
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 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.
* TFP Switch 1
* TFP Switch 3
* TFP Switch 4
* TFP 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 2) Control Valve Body Cleaning and Inspection (Gen 2).
• 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.
P0796 - Transmission Cooling/Lubrication
* Restriction/leak in OAC, oil to air, cooler/radiator.
* Restricted/leaking/kinked/damaged transmission oil cooler lines.
* Restriction/leak in transmission fluid pump assembly.
P0796 - Input Shaft Support
Input shaft tower seals damaged or leaking.
P0796 - 4-5-6 Clutch Housing Assembly
4-5-6 Clutch Piston Assembly damaged/leaking.
P0796 - Torque Converter (w/Fluid Pump) Housing Assembly
* Fluid pump housing vanes/rotor/slide damaged/scored.
* Fluid pump or torque converter overstressed due to high temperature.
P0796 - 4-5-6 Reaction Carrier Hub Assembly
4-5-6 reaction carrier Hub/Shaft - broken hub weld.
P0796 or P0797 - Control Valve Body Assembly
4-5-6 Regulator Valve stuck/sticking - debris, binding, damaged valve, or scored bore.
P0796 or P0797 - Q8 Control Solenoid Valve Assembly
* Clutch Pressure Control Solenoid 3 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 repair.
* Internal Components Removal Internal Components Removal
* 3-5-Reverse and 4-5-6 Clutch Housing Disassemble (6T30/40/45/50 - Gen 2) 3-5-Reverse and 4-5-6 Clutch Housing Disassemble (6T30/40/45/50 - Gen 2)
* 3-5-Reverse and 4-5-6 Clutch Housing Assemble (6T30/40/45/50 - Gen 2) 3-5-Reverse and 4-5-6 Clutch Housing Assemble (6T30/40/45/50 - Gen 2)
* 3-5-Reverse and 4-5-6 Clutch Housing, and Input, Reaction, and Output Carrier Installation 3-5-Reverse and 4-5-6 Clutch Housing, and Input, Reaction, and Output Carrier Installation
* Perform the Transmission Adaptive Values Learn Transmission Adaptive Values Learn following all transmission related repairs.
* Refer to Control Module References Control Module References for Q8 Control Solenoid Valve Assembly replacement, programming and setup.