For 1990-2009 cars
Master Electrical Component List
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice
Control Module References

### Circuit Description

The torque converter clutch (TCC) release switch is part of the automatic transmission fluid pressure (TFP) manual valve position switch. The TFP manual valve position switch is attached to the control 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, thus opening the switch. When the voltage is high on the circuit, the TCM recognizes that the TCC is no longer engaged.

When 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 MAP DTCs P0107 or P0108.

• | No ISS DTCs P0716 or P0717.

• | No TCC performance DTCs P0741 or P0742.

• | No TCC electrical DTCs P2763 or P2764.

• | The engine is running for 5 seconds.

• | The transmission fluid temperature (TFT) is 20-130°C (68-266°F).

• | The engine torque is greater than 50 N·m (37 lb ft).

• | The TCC is commanded OFF.

• | The TCC slip speed is greater than 100 RPM.

• | The vehicle speed is greater than 16 km/h (10 mph).

### Conditions for Setting the DTC

The TCC release switch is closed, release fluid pressure not present, for 8 seconds, twice during the same trip.

### Action Taken When the DTC Sets

• | The TCM illuminates 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 inhibits 4th gear when in HOT mode.

• | The TCM freezes transmission adaptive 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

Ensure the wiring harness is not stretched too tightly or other components are pressing on the connector body. Also, inspect for proper clearance to any other components and wiring. Refer to Testing for Intermittent Conditions and Poor Connections .

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step tests the ability of the TCM to recognize a grounded circuit.

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install a scan tool.
2. Start the engine.

Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear DTC Information function will erase the stored Freeze Frame and Failure Records from the TCM.

3. Record the Freeze Frame and Failure Records.
4. Clear the DTC.
5. With a scan tool, observe the TCC Release Pressure parameter.

Does the scan tool display Yes for TCC release pressure?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the AT inline 20-way connector. Additional DTCs may set.
3. Turn ON the ignition, with the engine OFF.
4. Observe the TCC Release Pressure parameter.

Does the scan tool display Yes for TCC Release Pressure parameter?

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 circuit 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 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:

1. Select DTC.
2. Select Clear DTC Info.
3. Operate the vehicle under the following conditions:

• | Start the vehicle.

• | Observe the TCC Release Pressure parameter on the scan tool.

• | Ensure that the TCC Release Pressure status is YES for at least 5 seconds.

4. Select Specific DTC.
5. Enter DTC P0842.

Has the test run and passed?

Go to Step 10

Go to Step 2

10 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK