P0740

DTC PO74O
TORQUE CONVERTER CLUTCH SYSTEM MALFUNCTION (LU - F)

Description
The lock-up engaging and disengaging conditions are set for each gear shift range gear position and shift pattern and correspond to the throttle position and vehicle speed and the duty solenoid is electronically controlled by Transmission Control Module (TCM) controls the lock-up clutch. The lock-up clutch engagement and disengagement are controlled by the lock-up control valve.

DTC Detecting Condition
Two consecutive trips with fault.

Trouble Symptom
- No lock-up occurs. (after Engine warm-up).
- No shift or excessive tight corner "braking".












1. Check any other DTC (Besides DTC P0740) on display.
[CHECK]: Is there any other DTC on display?
[YES]: Inspect the relevant DTC chart.
[NO]: Go to step 2.

2. Check duty solenoid B circuit.
[CHECK]: Is there any trouble in duty solenoid B circuit?
[YES]: Repair or replace duty solenoid B circuit.
[NO]: Go to step 3.

3. Check throttle position sensor circuit.
[CHECK]: Is there any trouble in throttle position sensor circuit?
[YES]: Repair or replace throttle position sensor circuit.
[NO]: Go to step 4.

4. Check vehicle speed sensor 1 circuit.
[CHECK]: Is there any trouble in vehicle speed sensor 1 circuit?
[YES]: Repair or replace vehicle speed sensor 1 circuit.
[NO]: Go to step 5.

5. Check vehicle speed sensor 2 circuit.
[CHECK]: Is there any trouble in vehicle speed sensor 2 circuit?
[YES]: Repair or replace vehicle speed sensor 2 circuit.
[NO]: Go to step 6.

6. Check engine speed input circuit.
[CHECK]: Is there any trouble in engine speed input circuit?
[YES]: Repair or replace engine speed input circuit.
[NO]: Go to step 7.

7. Check inhibitor switch circuit.
[CHECK]: Is there any trouble in inhibitor switch circuit?
[YES]: Repair or replace inhibitor switch circuit.
[NO]: Go to step 8.

8. Check brake light switch circuit.
[CHECK]: Is there any trouble in brake light switch circuit?
[YES]: Repair or replace brake light switch circuit.
[NO]: Go to step 9.

9. Check automatic transmission fluid (ATF) temperature sensor circuit.
[CHECK]: Is there any trouble in ATF temperature sensor circuit?
[YES]: Repair or replace ATF temperature sensor circuit.
[NO]: Go to next [CHECK].

[CHECK]: Is there poor contact in TCM connector?
[YES]: Repair poor contact in TCM connector.
[NO]: Go to next [CHECK].

[CHECK]: Is there any mechanical trouble in automatic transmission?
[YES]: Repair or replace automatic transmission.
[NO]: Replace TCM with a new one.