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) 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 the TCC is no longer engaged.
If the TCM determines the TCC release switch is closed indicating the TCC is applied and the TCC slip speed indicates 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 performance DTCs P0741 or P0742. |
| • | No TCC PWM solenoid valve electrical DTC P2763 or P2764. |
| • | The engine speed is greater than 500 RPM or 5 seconds. |
| • | The TCC is commanded OFF. |
| • | The transmission fluid temperature is between 20°C (68°F) and 130°C (266°F). |
| • | The TCC slip speed is greater than 80 RPM. |
| • | The engine torque is 50 N·m (37 lb ft) or greater. |
| • | The vehicle speed is 16 km/h (10 mph) or greater. |
Conditions for Setting the DTC
The TCC release pressure switch is closed indicating release pressure is not present for 10 seconds twice during the same ignition cycle.
Action Taken When the DTC Sets
| • | The TCM requests the engine control module (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 commands the TCC ON at maximum capacity. |
| • | 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 fourth gear when in Hot Mode. |
| • | 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 after 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
| • | Do not replace the torque converter for this condition. Refer to 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 inline 20-way connector body. |
| • | Inspect for proper clearance to all other components and wiring. Refer to Testing for Intermittent Conditions and Poor Connections . |
Step | Action | Values | 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 automatic transmission 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 automatic transmission 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 automatic transmission 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 |
