Service Code Output Format
SERVICE CODESThe EEC System Communicates service information by way of the Self-Test service codes. These service codes are two-digit numbers representing the results of 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 SUPER STAR II Tester, or check engine light. On the voltmeter each pulse corresponds to a needle sweep.
1. Code cycle break
2. First digit of service code (tens position) during one cycle.
3. Second digit of service code (ones position) during one cycle.