On-Board Diagnostic System

A fail safe item is identified by a code number. A code number (fail safe item) is stored in memory when four associated diagnostic trouble code numbers are output. The fourth diagnostic trouble code number is replaced with a code number (fail safe item) when stored in memory.

When a fail safe code number is output, three associated diagnostic trouble code numbers are simultaneously output.

The fail safe function which locks control at the 3rd or 2nd speed is canceled when the ignition key is turned OFF. (The code numbers stay in memory.)

If a constant output is measured (including 0 volts) with no changes, then the transmision control module has failed, and the transmission will be limited to 3rd gear.