P0740

Diagnostic Chart:

Wiring Diagram:

Circuit Description

In conjunction with the Torque Converter Clutch (TCC) Pulse Width Modulated (PWM) Solenoid Valve, the TCC Solenoid Valve controls fluid acting on the TCC Valve. The TCC Valve controls the application and release of the TCC. The TCC solenoid is a normally-open, ON/OFF device. The solenoid attaches to the transmission case assembly extending into the pump cover. The PCM monitors the Throttle Position Sensor (TPS) voltage, the vehicle speed, and other inputs in order to determine when to energize the TCC Solenoid Valve. Circuit 439 supplies ignition voltage directly to the TCC Solenoid Valve. The PCM controls the solenoid by providing the ground path through circuit 422.

If the PCM detects a continuous open or a short to ground in the TCC Solenoid Valve circuit or the TCC Solenoid Valve, then DTC P0740 sets. DTC P0740 is a type A DTC.

Conditions for Setting the DTC

- The system voltage is 10-16 volts.
- The is greater than 400 RPM for 5 seconds and not in fuel cut off.
- The PCM commands the solenoid ON and the voltage remains high (Battery Positive Voltage).
- The PCM commands the solenoid OFF and the voltage remains low (0 volts).
- All conditions met for 5 seconds.

Action Taken When the DTC Sets

- The PCM inhibits TCC engagement.
- The PCM inhibits 4th gear if in hot mode.
- 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

- Inspect the wiring for any poor electrical connections at the PCM. Inspect the wiring at the TCC brake switch. Look for the following problems:
- A bent terminal
- A backed out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation
- When diagnosing for an intermittent short or an open, massage the wiring harness while watching the test equipment for changes.
- With the TCC engaged, the TCC slip speed should be -20 to +20 RPM.
- A short to ground in the TCC Solenoid Valve circuit may also set a TCC Stuck On DTC P0742.

Test Description

The numbers below refer to the step numbers on the diagnostic chart.
4. This step verifies that the solenoid receives current.
6. This step verifies the ability of the PCM and the wiring to control the ground circuit.
11. This step measures the resistance of the TCC Sol. Valve and the Automatic Transmission wiring harness.