- Powertrain/On-Board Diagnostic System Check

On-Board Diagnostic (OBD) System Check:

MIL And DLC Circuit:

CIRCUIT DESCRIPTION
The on board diagnostic (OBD) 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
The numbers below refer to circled numbers on the diagnostic chart.

1. This step is to determine if the Tech 1 can establish communication with the Powertrain Control Module (PCM). If it cannot, "No DLC Data" will be displayed on the Tech 1.
2. This test is to determine if the PCM can control the Malfunction Indicator Lamp (MIL) using the MIL system check.

DIAGNOSTIC AIDS
This vehicle is equipped with a PCM utilizing an Electrically Erasable Programmable Read Only Memory (EEPROM).

When diagnostics call for replacement of the PCM, the new PCM must be programmed.