Description of On-Board Diagnostics

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

NOTE: Warning and diagnostic codes can be read only when the overdrive switch is "ON". If "OFF", the overdrive "OFF" indicator is lit continuously and will not blink.

a. If a malfunction occurs within the 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.






b. The diagnostic code can be read by the number of blinks of the overdrive OFF indicator when terminals TE1 and E1 are short-circuited.






c. The throttle position sensor or brake signal are not indicated, but inspection can be made by checking the voltage at terminal ECT of the service connector (diagnosis).
d. The signals to each gear can be checked by measuring the voltage at terminal ECT of the service connector while driving.

2. The diagnostic (malfunction) code is retained in memory by the CPU 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 fuse EFI (15A) or disconnect the TCCS ECU connector to cancel out the diagnostic (malfunction) code.

NOTE:
- 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 k-ohms/V.