Reading Diagnostic Trouble Codes

"Check Engine" Light And Diagnostic Connector:

To access trouble codes, a test lead (white wire) and ground lead (black wire) are branched from the wiring harness under the center console near the ECM. With the ignition "ON" connect these two leads together. The "Check Engine" light will begin to flash code 12. Code 12 consists of one flash, a short pause, then two flashes. After a longer pause, code 12 will repeat two more times. This check indicates that the on-board diagnostic system is functioning. If no other codes are present, the cycle will repeat until the ignition is switched "OFF."