DTC P0740. Chevrolet Joy 2008

For 1990-2009 cars

### Circuit Description

The transmission control module (TCM) sends an output duty cycle signal which activates the lock-up solenoid . This signal is used to control torque converter lock-up piston inside the torque converter.

### DTC Descriptor

This diagnostic procedure supports the following DTC: DTC P0740 Torque Converter Clutch (TCC) Electrical Circuit

### Conditions for Setting the DTC

When the transmission control module (TCM) sends an output duty cycle signal to activate the lock-up solenoid, but the return signal is received as OFF by the monitoring signal.

### Action Taken When the DTC Sets

• | The malfunction indicator lamp (MIL) will illuminate.

• | When the TCM detects failures on two consecutive driving cycles.

• | Lock-up control is inhibited and the solenoid is turned off.

### Conditions for Clearing the MIL/DTC

• | The TCM stops sending MIL request to the ECM when no further failures are detected after 3 consecutive driving cycles and the ECM turns off the MIL on the next driving cycle (MIL off at the 4th driving cycle).

• | A history DTC will clear after 40 consecutive warm-up cycles without a fault.

• | Clear the DTCs with a scan tool.

### Diagnostic Aids

When DTC P0740 sets, the possible cause of the fault could be:

• | Open or short circuit in the wiring harness and/or connector

• | Lock-up malfunction

• | Faulty TCM

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Automatic Transmission? | -- | Go to Step 2 | Go to Diagnostic System Check - Automatic Transmission

2

1. Turn the ignition OFF.
2. Disconnect the lock-up solenoid wiring connector.
3. Check the resistance between the lock-up solenoid connector terminal 4 and Ground.

Is the resistance in the specified range?

13 ohms 20°C (70°F)

Go to Step 3

Go to Step 5

3 | Perform a continuity check between the lock-up solenoid connector terminal 4 and the TCM connector Terminal 3. Is there continuity? |  | Go to Step 4 | Go to Step 5
4 | Replace the Lock-up solenoid. Does the lock-up solenoid operate correctly? | -- | Go to Step 7 | Go to Step 6
5 | Repair the wiring harness as necessary. Refer to Wiring Repairs . Is the action complete? | -- | Go to Step 7 | --
6 | Replace the TCM. Refer to Transmission Control Module Replacement . Is the action complete? | -- | Go to Step 7 | --

7

1. After the repair, use a scan tool clear info function and road test the vehicle.
2. Review the DTC info.
3. Observe the DTC Information with a scan tool.

Did the last test fail or is the current DTC displayed?

--

Go to Step 2

System OK