Transmission Control Systems: Description and Operation

DESCRIPTION
1. A self-diagnosis function is built into the electrical control system. Warning is indicated by the overdrive OFF indicator light.

HINT: Warning and diagnostic trouble code can be read only when the overdrive switch is ON. If OFF, the overdrive OFF light is lit continuously and will not blink.

- If a malfunction occurs within the vehicle speed sensors (No. 1 or 2) or solenoids (No. 1 or 2), the overdrive OFF light will blink to warn the driver.
However, there will be no warning of a malfunction with lock-up solenoid.




- The diagnostic trouble code can be read by the number of blinks of the overdrive OFF indicator light when terminals TE1 and E1 are connected.




- The throttle position sensor or brake signal are not indicated, but inspection can be made by checking the voltage at terminal TT of the date link connector.
- The signals to each gear can be checked by measuring the voltage at terminal TT of the date link connector while driving.




2. The diagnostic trouble code is retained in memory by the Engine Control Module (ECM) and due to back-up voltage, is not canceled out when the engine is turned off. Consequently, after repair, it is necessary to turn the ignition switch off and remove the EFI fuse (15A) or disconnect the ECM connector to cancel out the diagnostic trouble code.

HINT:
- Low battery voltage will cause faulty operation of the diagnosis system. Therefore, always check the battery first.
- Use a voltmeter and ohmmeter that have an impedance of at least 10 kohms/volts.