Reading Trouble Codes

When the DDC tester is connected to the ALCL connector (ignition on and engine not running), the CEL on the tester will flash a Code 12, indicating that the ECM is operating properly and can recognize a fault in the system.

Codes are indicated by flashes of the CEL. For example, FLASH, pause, FLASH, FLASH, longer pause, identifies Code 12. This will repeat three times, followed in ascending numerical order by any stored codes (each repeated 3 times).

If no other codes are stored, the light will continue to flash Code 12. Within about 5 seconds of engine start the light should go out, indicating that the ECM has not detected a fault.