Without "SCAN" Tester
The ECM stores component failure information for the CCC system under a related trouble code which can be recalled for diagnosis and repair. When recalled, these codes will be displayed by flashes of the "SERVICE ENGINE SOON" light. Trouble codes are displayed starting with the lowest numbered code. Only codes that represent a definite malfunction will be shown.
Trouble codes are read by counting flashes of the "SERVICE ENGINE SOON" light, or by reading output on a diagnostic tester ("SCAN" tester) connected to the ALCL connector. These special tools are faster and more accurate, but are not mandatory.
If a "SCAN" tester is not available, read the flashes of the "SERVICE ENGINE SOON" lamp. For example, "FLASH", "FLASH", pause, "FLASH", longer pause, identifies "21". The first flashes are the first digit of the code, second flashes are the second digit.