P0740

P0740 Torque Converter

Description

- The torque converter clutch solenoid valve is activated, with the gear in D4, D5 by the TCM in response to signals sent from the output speed sensor and accelerator pedal position sensor (throttle position sensor). Torque converter clutch piston operation will then be controlled.
- Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
- When the accelerator pedal is depressed (less than 1/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.

SDT Reference Value in Data List Mode






On Board Diagnosis Logic

- This is an OBD-II self-diagnostic item.
- Diagnostic trouble code "P0740" with SDT or 3rd judgment flicker without SDT is detected under the following conditions.

- When TCM detects an improper voltage drop when it tries to operate the solenoid valve.
- When TCM detects as irregular by comparing target value with monitor value.

Possible Cause

- Torque converter clutch solenoid valve
- Harness or connectors
(The solenoid circuit is open or shorted.)

DTC Confirmation Procedure

CAUTION:

Always drive vehicle at a safe speed.

NOTE:

If "DTC Confirmation Procedure" has been previously performed, always turn ignition switch "OFF" and wait at least 10 seconds before performing the next test.

After the repair, perform the following procedure to confirm the malfunction is eliminated.

with SDT

1 Turn ignition switch "ON". (Do not start engine.)
2 Select "Data list" mode for "AT" with SDT.
3 Start engine and maintain the following conditions for at least 5 consecutive seconds.
VHCL/S SE-A/T: 80 km/h (50 MPH) or more
ACCELE POSI: 0.5/8 - 1.0/8
SLCT LVR POSI: "D" position
Driving location: Driving the vehicle uphill (increased engine load) will help maintain the driving conditions required for this test.
4 If DTC is detected go to "Diagnosis Procedure".

with GST

Follow the procedure "WITH SDT".

Diagnosis Procedure

1. CHECK INPUT SIGNAL

With SDT
1 Turn ignition switch ON.
2 Select "MAIN SIGNALS" in "Data list" mode for "AT" with SDT.
3 Start engine.
4 Read out the value of "TCC SOLENOID" while driving.

OK or NG
OK
GO TO 4.
NG
GO TO 2.

2. CHECK TCM POWER SUPPLY AND GROUND CIRCUIT

Check TCM power supply and ground circuit. Refer to [Main Power Supply and Ground Circuit Check] Main Power Supply and Ground Circuit Check.

OK or NG
OK
GO TO 3.
NG
Repair or replace damaged parts.

3. DETECT MALFUNCTIONING ITEM

Check the following.
- The A/T assembly harness connector pin terminals for damage or loose connection with harness connector.

OK or NG
OK
Replace the control valve with TCM. Refer to [Control Valve with TCM: Removal and Installation] Service and Repair.
NG
Repair or replace damaged parts.

4. CHECK DTC

Perform "DTC Confirmation Procedure".
- Refer to "DTC Confirmation Procedure".

OK or NG
OK
INSPECTION END
NG
GO TO 2.