Diagnostic Trouble Code (DTC) Output Format Description

Self-Test code. Code cycle break:

Self-Test code. First digit:

Self-Test code. Second digit:

The engine control system communicates service information by way of the self-test service codes. These service codes are two digit numbers representing the results of the self-test.
The service codes are transmitted on the self-test output (STO) line found in the vehicle self-test connector. They are in the form of timed pulses, and read by the technician on a voltmeter or on the Star tester.
1. Code cycle break: The time between service codes code cycles is 4.0 seconds (the time the light is off), Fig. 4.
2. First digit of service code (tens position): The digit in the tens position of the service codes represents the number of times the buzzer in on 1.2 seconds during one cycle, Fig. 5.
3. Second digit of service code (ones position): The digit in the ones position of the service code represents the number of times the buzzer is on the 0.4 seconds during one cycle, Fig. 6.