Circuit Description
The PCM energizes the TCC Solenoid Valve by creating a ground path on
circuit 422. When grounded (energized) by the PCM, the TCC Solenoid Valve
stops converter signal oil exhaust. Converter signal oil pressure will increase.
Increased converter signal oil pressure will move the TCC valve. The TCC Solenoid
Valve will de-energize when the PCM no longer provides a ground path. When
the TCC Solenoid Valve is de-energized, the valve will release fluid and release
the TCC.
If the PCM detects a low torque converter slip when the TCC is OFF,
then DTC P0742 sets. DTC P0742 is a type A DTC.
Conditions for Setting the DTC
| • | No TP DTCs P0122 or P0123 |
| • | No TFP Valve Position Switch DTC P1810 |
| • | No TCC PWM Solenoid Valve DTC P1860 |
| • | No TCC Solenoid Valve DTC P1864 |
| • | The TP angle is greater than 15%. |
| • | The engine speed is greater than 400 RPM for 8 seconds
and not in fuel cutoff. |
| • | The engine vacuum is 0-106 kPa. |
| • | The engine torque is 54-542 N·m (40-400 lb ft). |
| • | The commanded gear is not 1st. |
| • | The gear range is D4, D3, or D2. |
| • | The TCC is commanded OFF. |
| • | The TCC slip speed is 20-30 RPM. |
| • | All conditions are met for 5 seconds. |
Action Taken When the DTC Sets
| • | The PCM freezes shift adapts from being updated. |
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after three consecutive ignition cycles
without a failure reported. |
| • | A scan tool can clear the DTC from the PCM history. The PCM clears
the DTC from the PCM history if the vehicle completes 40 warm-up cycles without
a failure reported. |
| • | The PCM cancels the DTC default actions when the fault no longer
exists and the ignition is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | The TCC may mechanically stick ON with the parking brake applied
and any gear range selected. In this case, the TCC fluid mechanically applies
the TCC. Mechanically applying the TCC may cause an engine stall. |
| • | A stuck TP sensor at greater than 15% will set this code. |
Test Description
The numbers below refer to the Step numbers on the diagnostic table.
-
This step tests the TCC for a mechanical
malfunction. When the PCM commands the TCC Solenoid Valve OFF, the slip speed
should increase.
DTC P0742 Torque Converter Clutch (TCC) Stuck ON
Step
| Action
| Value(s)
| Yes
| No
|
1
| Was the Powertrain On-Board Diagnostic (OBD) System Check performed?
| --
|
Go to Step 2
| Go to
Powertrain On Board Diagnostic (OBD) System Check
, Section 6
|
2
|
- Install the scan tool.
- With the engine OFF, turn the ignition switch to the RUN position.
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze
Frame and the Failure Records for reference. The Clear Info function will
erase the data.
- Record the DTC Freeze Frame and Failure Records.
- Use the scan tool in order to verify the TP Sensor operation.
Are the TP Sensor values within the range shown?
| 0.6 - 5.0 volts
|
Go to Step 3
| Go to Diagnostic Aids
|
3
|
- Drive the vehicle in the D4 drive range in fourth gear under steady
acceleration, with a TP angle greater than 25%.
- Display the TCC Solenoid Valve state on the scan tool.
While the valve state is OFF, does the scan tool display a TCC Slip Speed in the range shown?
| -20 to +20 RPM
|
Go to Step 4
| Go to Diagnostic Aids
|
4
| The TCC is mechanically stuck ON. Inspect the TCC for the following conditions:
| • | A clogged exhaust orifice in the TCC Solenoid Valve |
| • | The converter clutch apply valve is stuck in the apply position. |
| • | A misaligned valve body gasket |
| • | A damaged valve body gasket |
| • | Restricted release passage |
| • | Refer to On-Vehicle Service |
Did you find and correct a problem?
| --
|
Go to Step 5
| --
|
5
|
- After the repair is complete, select DTC.
- Select Clear Info.
| • | Hold the throttle at 25%. Accelerate to 88 km/h (55 mph).
If the throttle moves more than 3%, stop the vehicle and begin again. |
| • | Ensure that the TCC slip speed is 100-1000 RPM for
5 seconds, with the TCC OFF. |
- Select Specific DTC. Enter DTC P0742.
Has the test run and passed?
| --
| System OK
|
Begin the diagnosis again. Go to Step 1
|
