P0740

Circuit Description
Based on signals from the Throttle Position (TP) sensor (throttle opening), the ignition coil and Engine Coolant Temperature (ECT) sensor, the Powertrain Control Module (PCM) will provide the ground for the Torque Converter Clutch (TCC) circuit. The TCC solenoid under control of the TCC relay, opens and closes the automatic transmission fluid passage to lock and unlock the TCC.

Conditions for Setting the DTC
One of the following two sets of conditions are detected for 5 seconds continuously:
^ First set of conditions:
- Transmission range switch OFF: (R, D, 2, L range).
- Engine speed less than 3500 rpm.
- Throttle angle is between 12.2° and 40.0°.
- Engine coolant temperature above 60°C (140°F).
- Vehicle speed is above 75.4 km/h (47 mph).
- Vehicle speed to engine speed ratio = 0.029 km/h:1 rpm.
^ Second set of conditions:
- Transmission range switch OFF (R, D, 2, L range).
- Throttle angle is between 20.0° and 44.0°.
- Engine coolant temperature above 60°C (140°F).
- Stoplamp switch is open (brake pedal released).
- Vehicle speed is between 35.8 and 50.9 km/h (22 and 32 mph).
- Vehicle speed to engine speed ratio = 0.029 km/h:1 rpm.

Action Taken When the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles with the malfunction present.

Conditions for Clearing the MIL/DTC
^ The Malfunction Indicator Lamp (MIL) will turn OFF after three consecutive drive cycles without a fault present.
^ DTC will clear after 40 consecutive warm-up cycles without a fault.
^ DTC can be cleared by using a scan tool or by disconnecting the Powertrain Control Module (PCM) battery feed.

Diagnostic Aids
Check for the following conditions:
^ Torque Converter Clutch (TCC) relay for proper resistance values and operation.
^ Torque Converter Clutch (TCC) solenoid valve and/or its circuit.
^ Torque Converter Clutch (TCC) solenoid pipes and seals.
^ Poor connection at the Powertrain Control Module (PCM), and at connectors C102, C104 and C301. Inspect harness connector for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.
^ Damaged harness. Inspect the wiring harness for damage.
^ If DTC P0740 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions since the DTC was last set. This may assist in determining how often the DTC sets.

DTC Confirmation Procedure
The DTC Confirmation Procedure outline is here as follows:
1. Turn the ignition switch to LOCK.
2. Connect the Scan Tool to Data Link Connector (DLC).
3. Start engine and warm up to normal operating temperature.
4. Use a Scan Tool to clear the following items from the PCM memory:
^ The DTC.
^ The pending DTC.
^ Freeze frame data.
5. Drive the vehicle to 43 km/h (27 mph) in Drive range for 10 seconds.
6. Increase the vehicle speed to 85 km/h (53 mph) in Drive range for 10 seconds.
7. Stop the vehicle.
8. Use the Scan Tool to inspect for DTC P0740.

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool is applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
2. This step inspects the circuit that controls the Torque Converter Clutch (TCC) relay.
3. This step inspects the circuit that powers the TCC relay.
4. This step inspects the TCC relay for proper resistance values.
5. This step inspects the TCC relay for proper resistance values.
6. This step inspects the TCC relay for proper resistance values.
7. This step inspects the TCC for proper resistance values
8. This step inspects the Powertrain Control Module (PCM) operation of the TCC relay control circuit.
9. This step inspects the TCC relay for proper solenoid operation.
10. This step inspects the power feed circuit between the Main Relay and the TCC relay.
12. This step inspects for a short to ground in the WHT wire between the TCC relay and TCC solenoid.
13. This step inspects for an open or high resistance in the WHT wire between the TCC relay and the TCC solenoid.
15. This step checks the performance of the TCC.
16. This step confirms the DTC is set due to a PCM malfunction.
24. This step confirms the TCC solenoid is not leaking when off.
25. This step confirms TCC solenoid opens when on.
26. This step confirms a malfunction within the mechanical portion of the TCC and not its electrical components.