P0742

Diagnostic Chart:

Wiring Diagram:

When torque converter clutch (TCC) is commanded off, the engine speed to turbine shaft speed ratio (delta) is monitored to assure TCC is off. TCC stuck on indicates that TCC was commanded off but the actual ratio (delta) across the torque converter, (engine speed/turbine shaft speed), is one to one or TCC on. TCC is turned Off by opening circuit 422 at the PCM/TC. A TCC stuck On will usually cause the engine to stall when reverse is selected.

DTC PARAMETERS

DTC P0742 is set when the PCM has detected the following conditions for more than four seconds twice per ignition cycle.

- Engine speed greater than 908 rpm.

- Turbine shaft speed is between 224 and 2800 rpm.

- TCC is commanded to release for more than 0.25 seconds.

- Load value (engine torque) is greater than 100.

- Speed delta (engine speed - turbine shaft speed) across torque converter is less than 84 rpm.

TEST DESCRIPTION

Numbered steps below refer to numbered steps on chart.

1. Check for DTCs P0740 or P0744. They must be eliminated first as a possible cause of DTC P0742.

NOTE: To check actuator operation, command actuator quick test using the Scan tool.

2. Check actuator operation. Use actuator quick check. The actuator quick test will PWM the actuators at a set rate. Listen and compare the noise of TCC gear actuator to that of other actuators. The noise of all should be similar. Actuator Quick Chart

3. The TCC release circuit may be leaking at the seal ring on the input shaft. This would allow release pressure to leak off to converter out circuit or lube circuit. Also a remote possibility is the ball pressed into the input shaft is loose.

REPAIR VERIFICATION

Monitor DTC menu "Code Status" for "Pass Since Code Clear" and "Pass This Ignition Cycle." When both have passed, repair is verified.

Criteria for pass:

- TCC commanded Off

- Speed ratio across torque converter is less than 1:1 for 12 seconds

DIAGNOSTIC AIDS

- When the PCM detects a fault in the circuit (open, ground, short), the PCM will open the circuit internally to protect the circuit.

- The TCC may be detected as stuck on when the transaxle is put into drive range. If TCC is stuck on at start-up, a stall may occur, and after a restart it will result in a 3rd or 4th gear start.