P0740

Circuit Description
In conjunction with the Torque Converter Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Sol. Valve), the Torque Converter Clutch Solenoid Valve Assembly (TCC Sol. Valve Assy.) controls the fluid acting on the Torque Converter Clutch (TCC) apply valve. This controls the TCC apply and release. The PCM monitors the throttle position, the vehicle speed and other inputs, in order to determine when to energize the TCC Sol. Valve Assy. Circuit 1039 supplies ignition voltage, and the Output Driver Module (ODM) within the Powertrain Control Module (PCM), provides ground. The PCM monitors voltage levels at the ODM. When the TCC Sol. Valve Assy. is commanded OFF, the PCM receives high voltage, and when the TCC Sol. Valve Assy. is commanded ON, the PCM receives low voltage.
When the PCM detects a continuous open or short to ground in the TCC Solenoid circuit then DTC P0740 sets. DTC P0740 is a type A DTC.

Conditions for Setting the DTC
^ System voltage is 10-16 volts.
^ The engine speed is greater than 500 RPM.
^ Not in fuel shut off.
^ The PCM commands the solenoid ON, and the voltage signal to the PCM remains high (B+).
^ The PCM commands the solenoid OFF, and the voltage signal to the PCM remains low (0 volts).
^ All conditions must be met for 5 seconds.

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ The PCM inhibits TCC.
^ The PCM inhibits 4th gear, if the transmission is in hot mode.

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 at the PCM, the transmission connector, TCC enable solenoid connector and all other circuit connecting points for the following conditions:
- A bent terminal
- A backed out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation
- Moisture intrusion
- Corrosion
^ When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
6. This step isolates the fault between the engine harness and the transmission harness.
8. This step verifies that circuit 422 is not open or shorted to power.
11. This step verifies that the TCC Sol. Valve is not shorted across its windings or increased its resistance.