DTC P0740/40: Lock-Up Control System

WARNING: This page is about a different car, the 1998 Honda Odyssey, 1998 Honda Accord, and 1998 Acura 2.3CL. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: DO NOT perform this DTC test until all other DTCs have been repaired first.

Using scan tool, retrieve A/T freeze data. Clear fault codes and road test vehicle under same conditions freeze data was recorded. If fault code returns, go to next step. If fault code does not return, problem is intermittent, check transaxle and PCM connections.
Using scan tool, check for any other DTCs. If any other DTCs are present, repair those DTCs first, then recheck for DTC P0740/40. If no other DTCs are present, go to next step.
Test line pressure. See HYDRAULIC PRESSURE TEST under TESTING in ACURA B6VA, HONDA BAXA, MDWA & M6HA OVERHAUL article. If line pressure is within specification, go to next step. If line pressure is not within specification, repair hydraulic system as necessary. See HYDRAULIC PRESSURE TROUBLE SHOOTING table under HYDRAULIC PRESSURE TEST in ACURA B6VA, HONDA BAXA, MDWA & M6HA OVERHAUL article.
Test clutch pressure. If clutch pressure is within specification, go to next step. If clutch pressure is not within specification, repair hydraulic system as necessary. See HYDRAULIC PRESSURE TROUBLE SHOOTING table under HYDRAULIC PRESSURE TEST in ACURA B6VA, HONDA BAXA, MDWA & M6HA OVERHAUL article.
Replace lock-up control solenoid valve/shift control solenoid valve "A" assembly. See LOCK-UP CONTROL SOLENOID VALVES/SHIFT CONTROL SOLENOID VALVE "A" under REMOVAL & INSTALLATION. Turn ignition off and clear codes. See CLEARING FAULT CODES under SELF-DIAGNOSTIC SYSTEM. Road test vehicle at over 50 MPH for more than one minute. Recheck DTCs. If DTC P0740/40 returns, go to next step. If DTC P0740/40 does not return, system is okay.
Replace A/T clutch pressure control solenoid assembly. See A/T CLUTCH PRESSURE CONTROL SOLENOID under REMOVAL & INSTALLATION. Turn ignition off and clear codes. See CLEARING FAULT CODES under SELF-DIAGNOSTIC SYSTEM. Road test vehicle at over 50 MPH for more than one minute. Recheck DTCs. If DTC P0740/40 returns, go to next step. If DTC P0740/40 does not return, system is okay.
Replace torque converter. Turn ignition off and clear codes. See CLEARING FAULT CODES under SELF-DIAGNOSTIC SYSTEM. Road test vehicle at over 55 MPH for more than one minute. Recheck DTCs. If DTC P0740/40 returns, replace transaxle and torque converter. If DTC P0740/40 does not return, system is okay.