Malfunction Indicator Lamp (MIL) Inoperative

Circuit Description

The A Powertrain On Board Diagnostic (OBD) System Check must be the starting point for any driveability complaint diagnosis. Before using this procedure, you should perform a careful visual/physical check of the PCM and engine grounds for being clean and tight. The A Powertrain On Board Diagnostic (OBD) System Check is an organized approach to identifying a problem created by an electronic engine control system malfunction. No MIL with the key ON, engine not running and DTC P0650 set suggests an open in the MIL driver circuit.

Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following items:

^ Inspect the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness. Refer to Diagrams.
^ If the engine runs OK, check for a faulty light bulb, an open in the MIL driver circuit, or an open in the instrument cluster ignition feed.
^ If the engine cranks but will not run, check for an open PCM ignition or battery feed or a poor PCM to engine ground.

Test Description

The numbers below refer to the step numbers on the Diagnostic Table:

2. A no MIL condition accompanied by a no start condition suggests a faulty PCM ignition feed or battery feed circuit.
9. Using a test light connected to battery positive voltage, probe each of the PCM ground terminals to ensure that a good ground is present.
16. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.