Entering Diagnostic Mode
- To obtain a stored trouble code from the ECM, the Assembly Line Communication Link (ALCL) is used. The ALCL connector is located in the passenger compartment. To enter the diagnostic mode, connect diagnostic terminal (terminal B) to ground (terminal A) with the engine stopped. See Fig 1 .
- The ECM will first display a code "12" to indicate the system is operating. Codes are displayed by flashing either the "CHECK ENGINE" or "SERVICE ENGINE SOON" light. Code 12 consists of a single flash, followed by a short pause, then 2 quick flashes in succession.
- Other codes are displayed in a similar manner. Each code will be displayed 3 times. After all codes have been displayed, the ECM will return to flashing code 12. It will flash code 12 until the diagnostic terminal is ungrounded.