P0740 Torque Converter Clutch Circuit Malfunction.
The torque converter is a fluid coupling between the engine and transmission. It loses some efficiency, which is what allows the engine to remain running when the transmission is in gear but the vehicle is not moving. Chrysler developed the torque converter lock-up clutch in the mid 1970's to increase fuel mileage. It engages above roughly thirty five to forty mph, in high gear, when the engine is warmed up. That locks the engine and transmission together solidly, similar to how a manual transmission's clutch does it, to eliminate that loss in efficiency.
Code 740 indicates the computer sees a break in the electrical circuit that runs the solenoid that turns the lock-up clutch on and off. In about nine out of ten times, this is caused by a cut wire or corroded connector terminal. Less commonly, it can be caused by a defective solenoid, and even less likely it is due to a problem with the computer.
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Thursday, April 26th, 2018 AT 2:58 PM
