Table A1-1 No Malfunction Indicator Lamp (MIL)

No Malfunction Indicator Lamp (MIL):

No Malfunction Indicator Lamp (MIL) (Continued):

Partial PCM Wiring Schematic:

Circuit Description

There should always be a steady Malfunction Indicator Lamp Malfunction Indicator Lamp (MIL) when the ignition switch is in the "ON" position and the engine is not running. System voltage is applied to the indicator bulb. The Powertrain Control Module (PCM) will control the MIL and turn it "ON" by providing a ground path through the MIL control circuit.


Diagnostic Aids

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

^ Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.

^ If engine runs OK, check for a faulty light bulb, or an open in the instrument cluster feed circuit.

^ With no MIL and the engine cranks but will not run, check for a faulty Main Relay.

^ With no scan tool data, no MIL, and with the engine cranks but will not run, it is possible to have the 5 volt reference circuit (i.e. Throttle Position (TP) Sensor, Manifold Absolute Pressure (MAP) Sensor, SC Motor) shorted to ground.

^ 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

Number(s) below refer to the step number(s) on the diagnostic table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. A no MIL condition accompanied by a no start condition suggest a faulty PCM ignition feed or battery feed circuit.

9. Using a test light to B+, probe each of the PCM ground terminals to ensure that a good ground is present. Refer to PCM / Diagrams / Connector View for terminal location of the PCM ground circuits.

18. Verifies proper operation of the MIL.