Warning Light Check

To test warning light and be sure the diagnostic system is operating, turn off the ignition switch, leave engine stopped and ground trouble code test lead located beneath dash (white wire with tracer, attached to ECM harness).
If the system is operating properly, when the ignition switch is turned to the "ON" position the "CHECK CARB" light will flash a code 12. Code 12 indicates proper operation of diagnostic system. The 12 will be flashed as follows: One flash, followed by a pause, and then two more flashes. After a longer pause, the code will repeat two more times.
NOTE: If fault is intermittent, "CHECK CARB" light may come on and then go out; however, fault problem will be stored in ECM memory so diagnosis can be performed.