Circuit Description
The torque converter clutch (TCC) release switch is part of the transmission fluid pressure (TFP) manual valve position switch. The TFP manual valve position switch is mounted to the transmission valve body. The TCC release switch is normally-closed.
The switch signals the transmission control module (TCM) that the TCC is released. This is accomplished by torque converter release fluid pressure acting on the switch contact which opens the circuit. When the circuit voltage is high, the TCM recognizes that the TCC is no longer engaged.
If the TCM determines that the TCC release switch is closed indicating that the TCC is applied and the TCC slip speed indicates that the TCC is not applied, then DTC P0842 sets. DTC P0842 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0842 Transmission Fluid Pressure (TFP) Sensor Circuit Low Voltage
Conditions for Running the DTC
| • | No ISS DTC P0716 or P0717. |
| • | No TCC PWM solenoid valve performance DTC P0741 or P0742. |
| • | No TCC PWM solenoid valve electrical DTC P2763 or P2764. |
| • | The engine speed is greater than 500 RPM for 5 seconds. |
| • | The TCC is commanded OFF. |
| • | The transmission fluid temperature is 20-130°C (68-266°F). |
| • | The TCC slip speed is greater than 80 RPM. |
| • | The vehicle speed is 16 km/h (10 mph) or greater. |
| • | The engine torque is greater than 50 N·m (37 lb ft). |
Conditions for Setting the DTC
The TCC release pressure switch is closed indicating release pressure is not present for 10 seconds continuous twice during the same ignition cycle.
Action Taken When the DTC Sets
| • | The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | The TCM commands maximum line pressure. |
| • | The TCM forces the TCC ON. |
| • | The TCM inhibits 4th gear if the transmission is in Hot Mode. |
| • | The TCM commands an alternate coast shift pattern where downshifts occur at higher vehicle speeds while coasting. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM inhibits TAP Shift functions. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records. |
| • | The TCM stores DTC P0842 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met. |
Conditions for Clearing the MIL/DTC
| • | The TCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool can clear the MIL/DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM. |
Diagnostic Aids
| • | DTC P0742 may also be set falsely due to the default action forcing the TCC on. |
| • | If DTC P0742 is also set, diagnose DTC P0842 first. |
| • | Do not replace the torque converter for this condition. Refer to the Torque Converter Replacement Guide for other concerns. |
| • | Ensure the wiring harness is not stretched too tightly or other components are pressing on the automatic transmission (A/T) inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Testing for Intermittent Conditions and Poor Connections . |
Step | Action | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |||||||
2 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear DTC Information function will erase the stored Freeze Frame and Failure Records from the TCM. Does the scan tool indicate Yes for TCC Release Pressure? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | ||||||
3 |
Does the scan tool indicate Yes for TCC Release Pressure? | Go to Step 4 | Go to Step 5 | ||||||
4 | Test the TCC release switch signal circuit for a short to ground between the AT inline 20-way connector and the TFP manual valve position switch. Refer to Testing for Short to Ground . Did you find a condition? | Go to Step 6 | Go to Step 7 | ||||||
5 | Test the TCC release switch signal for a short to ground between the TCM and the AT inline 20-way connector. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 8 | ||||||
6 | Replace the AT wiring harness assembly. Refer to Wiring Harness Replacement . Did you complete the replacement? | Go to Step 9 | -- | ||||||
7 | Replace the TFP manual valve position switch. Refer to Transmission Fluid Pressure Manual Valve Position Switch Replacement . Did you complete the replacement? | Go to Step 9 | -- | ||||||
8 | Replace the TCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 9 | -- | ||||||
9 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | Go to Step 10 | Go to Step 2 | ||||||
10 | With a scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | System OK |
