6T40/6T45 - Automatic Transmission

DTC P0796 or P0797

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 P0796
- Clutch Pressure Control (PC) Solenoid 3 - Stuck Off

DTC P0797
- Clutch Pressure Control (PC) Solenoid 3 - Stuck On




Diagnostic Fault Information

The following fault table gives examples of how hydraulic circuit problems and malfunctioning hard parts affect the transmission operation.










Circuit/System Description

The clutch pressure control (PC) solenoid 3 is part of the control solenoid (w/body and TCM) valve assembly. The control solenoid (w/body and TCM) valve assembly has no serviceable parts. The clutch PC solenoid 3 is a normally high-pressure control solenoid which provides fluid pressure to the low and reverse/4-5-6 clutch regulator valve which regulates the transmission fluid pressure to the low and reverse/4-5-6 clutch. The TCM controls the solenoid pressure by regulating the exhaust fluid. When the TCM commands the solenoid off, the exhausting fluid is stopped and the low and reverse/4-5-6 pressure is high. When commanded on, the clutch PC solenoid 3 regulates the amount of exhausting transmission fluid. Solenoid power is supplied by the TCM through a high side driver (HSD). The HSD protects the circuits and components that the TCM powers. Should the circuit overload the driver will shutdown. After the overload is removed the HSD resets. The TCM calculates gear ratio based on data from the automatic transmission input speed sensor (ISS) and the output speed sensor (OSS). The TCM compares the known transmission gear ratio to a calculated gear ratio for each commanded gear.


Conditions for Running the DTC


P0796
* No ISS DTCs P0716 or P0717.
* No OSS DTCs P0722 or P0723.
* No IMS DTCs P1825 or P1915.
* The ignition voltage is between 9.0 volts and 19.0 volts.
* The transmission fluid temperature is 0°C (32°F) or greater.
* The HSD is enabled.
* Low and reverse/4-5-6 clutch is commanded ON.



P0797
* No ISS DTCs P0716 or P0717.
* No OSS DTCs P0722 or P0723.
* No IMS DTCs P1825 or P1915.
* The ignition voltage is between 9.0 volts and 19.0 volts.
* The transmission fluid temperature is 0°C (32°F) or greater.
* The HSD is enabled.
* Low and reverse/4-5-6 clutch is commanded OFF.



Conditions for Setting the DTC

P0796

The TCM detects an incorrect on-coming clutch gear ratio, or flare, when the low and reverse/4-5-6 clutch is commanded ON for 6.0 seconds and the transmission input shaft speed is 33 RPM or greater from the anticipated input shaft speed for 4.0 seconds.

P0797

The TCM detects an incorrect off-going clutch gear ratio, or tie-up, when the low and reverse/4-5-6 clutch is commanded OFF for 1.0 seconds and the transmission input shaft speed is 33 RPM or less from the anticipated input shaft speed for 1.0 second.


Action Taken When the DTC Sets

* DTCs P0796 and P0797 are Type A DTCs.
* The TCM commands maximum line pressure.
* The TCM inhibits TCC.
* The TCM freezes transmission adaptive functions.
* The TCM inhibits TAP Up/TAP Down.



Conditions for Clearing the DIC/DTC

DTCs P0796 and P0797 are Type A DTCs.


Diagnostic Aids

* DTC P0796 detects neutral when 4th, 5th, or 6th gear is commanded.
* DTC P0797 detects a tie-up condition when shifting from 4th, 5th, or 6th.
* 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

* Drive Range - Fourth Gear (Drive Range, Fourth Gear)
* Drive Range, Fifth Gear (Drive Range, Fifth Gear)
* Drive Range, Sixth Gear (Drive Range, Sixth Gear)

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)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference

Control Module References for scan tool information
Special Tools

* DT-48616 Control Solenoid Test Plate
* DT-48616-10 Adapter Harness



Circuit/System Verification

1. Perform the Transmission Fluid Check (Transmission Fluid Check) .
2. Operate the vehicle in DRIVE with the calculated throttle position greater than 15 percent to obtain 72 km/h (45 mph) and achieve 5th gear. Perform this maneuver 2 times.

• If the DTC resets, go to Circuit/System Testing.




Circuit/System Testing


Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.


1. Perform the Line Pressure Check (Line Pressure Check) .

• 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 Transmission Control Module Assembly Cleaning) 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 Transmission Control Module Assembly Inspection) .

• 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 Transmission Control Module 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 if found in the valve body, repair or replace the valve body as necessary.

6. Inspect the low and reverse/4-5-6 clutch assembly for damage.

• If a concern is found in the low and reverse/4-5-6 clutch assembly, repair or replace as necessary.




Component Testing

Operating the transmission under the following conditions will verify that the PC solenoid or a portion of the hydraulic control circuit is not functioning as it should.










Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Important: 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 for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming.
* Perform the Service Fast Learn Adapts (Programming and Relearning) following all transmission related repairs.
* Perform the:

- Internal Components Removal (Overhaul)
- 3-5-Reverse and 4-5-6 Clutch Housing Disassemble (Overhaul)
- 3-5-Reverse and 4-5-6 Clutch Housing Assemble (Overhaul)
- 3-5-Reverse and 4-5-6 Clutch Housing, and Input, Reaction, and Output Carrier Installation (Overhaul)