6T70/6T75 - Automatic Transmission

DTC P0741 or P0742

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0741
- Torque Converter Clutch (TCC) - Stuck Off

DTC P0742
- Torque Converter Clutch (TCC) - Stuck On

Circuit/System Description

The torque converter clutch (TCC) pressure control (PC) solenoid is part of the control solenoid (w/body and TCM) valve assembly and is not serviced separately. The shift solenoid (SS) 1 supplies transmission fluid to the TCC PC solenoid when commanded OFF. The TCC PC solenoid regulates transmission fluid through the TCC regulator valve in the lower valve body and the TCC control valve in the pump, to the TCC when commanded ON and exhausts fluid when commanded OFF. When the TCC is applied, the engine is coupled directly to the transmission.

Conditions for Running the DTC

* No DTCs P0716 or P0717.
* No DTCs P0722 or P0723.
* No DTCs P0741 or P0742.
* No DTC P1751 (P0742 only).
* No DTCs P2762, P2763, or P2764.
* The engine run time is greater than 5 seconds.
* The ignition voltage is between 8.6 volts and 19.0 volts.
* The transmission fluid temperature (TFT) is 20-130°C (68-266°F).
* The calc. throttle position is greater than 8 percent.
* The engine torque is greater than 50 N.m (36 lb ft) for DTC P0741 and greater than 80 N.m (59 lb ft) for P0742.
* The 2nd gear ratio is between 1.42-1.63.
* The 4th gear ratio is between 1.06-1.23.
* The 5th gear is between 0.79-0.90.
* The 6th gear is between 0.62-0.71.

Conditions for Setting the DTC

P0741

The TCM detects TCC slip greater than 50 RPM for 6 seconds when the TCC is commanded ON twice during the same ignition cycle.

P0742

The TCM detects the TCC slip between -20 and 30 RPM for 25 seconds or greater when the TCC is commanded OFF. The vehicle speed is greater than 16 km/h (10 mph) and the commanded gear is 2nd or higher for 6 times during the same ignition cycle.

Action Taken When the DTC Sets

* DTCs P0741 and P0742 are Type B DTCs.
* Inhibit high gear in Hot Mode.
* The TCM inhibits TCC.
* The TCM freezes transmission adaptive functions.

Conditions for Clearing the DIC/DTC

DTCs P0741 and P0742 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. Ensure the transmission fluid level is correct and there are no leaks.

Special Tools Required

DT-47825 Control Solenoid Test Plate

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 8 percent and ensure TCC is commanded ON and OFF a minimum of 5 times.

* If the DTC resets, go to Component Testing.

Component Testing

1. Perform the Control Solenoid Valve and Transmission Control Module Assembly Cleaning in an attempt to clean or free up a potential sticking valve of dirt or debris. Control Solenoid Valve and Transmission Control Module Assembly Cleaning

* If the DTC resets after the cleaning procedure perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection. Control Solenoid Valve and Transmission Control Module Assembly Inspection

2. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test to test for a stuck open or stuck closed TCC PC solenoid valve inside of the control solenoid (w/body and TCM) valve assembly. Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test

* If a stuck open or closed valve is found, replace the control solenoid (w/body and TCM) valve assembly.

3. Inspect the lower control valve body for a stuck valve, debris or damage.

* If you found a valve body concern, repair or replace the lower control valve body as necessary.

4. Inspect the TCC control valve in the pump.

* If you found a TCC control valve concern, repair or replace the TCC control valve or pump as necessary.

5. Inspect the torque converter assembly for damage or discoloration.

* If you found a torque converter assembly concern, replace the torque converter assembly as necessary.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Control valve body replacement - refer to Control Valve Lower Body and Upper Body Replacement.
* Perform the Torque Converter Removal.
* Control solenoid (w/body and TCM) valve assembly replacement - Refer to Programming and Relearning for replacement, setup, and programming.
* Transmission pump repair or replacement - refer to Torque Converter and Differential Housing, Front Differential Transfer Drive Gear, and Front Differential Carrier Removal and Torque Converter and Differential Housing Installation.
* Perform the Service Fast Learn Adapts. Programming and Relearning