Circuit Operation

A/T control relay (terminal number 1) receives the battery positive voltage from the battery.
When turning the ignition switch to the "ON" position the PCM receives battery voltage from the ignition switch (terminal 98). Then the PCM (terminal number 50) applies a voltage to the A/T control relay (terminal number 4), and the A/T control relay switch is turned on. When the A/T control relay switch is turned on, the battery applies a power supply voltage to the PCM (terminal numbers 77 and 89).