- Powertrain/On-Board Diagnostic System Check

On-Board Diagnostic Circuit Check:

On-Board Diagnostic Circuit Check Wiring Diagram.:

Circuit Description:

The on-board diagnostic system check is an organized approach to identifying a problem created by an electronic engine control system malfunction. It must be the starting point for any driveability complaint diagnosis, because it directs the service technician to the next logical step in diagnosing the complaint. Understanding the chart and using it correctly will reduce diagnostic time and prevent the unnecessary replacement of good parts.

Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. This step is to determine if the Scan tool can establish communication with the ECM. If it cannot, "No DLC Data" will be displayed on the Scanner.

2. This test is to determine if the ECM can control the MIL using the MIL system check.

Important:

This vehicle is equipped with an Engine Control Module (ECM) utilizing an Electrically Erasable Programmable Read Only Memory (EEPROM).

When diagnostics call for replacement of the ECM, the new ECM must be programmed. Refer to "ECM Replacement and Programming Procedures" under
Service and Repair.