Chart A-1 No Check Engine Light

Chart A-1:

CIRCUIT DESCRIPTION:

There should always be a steady "CHECK ENGINE" light when the ignition is "ON" and engine is not running. Battery voltage is applied to the light bulb. The ECM will control the light and turn it "ON" by providing a path to ground.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. An open gage fuse could indicate a short to ground in the gage fuse circuit.

2. Indicates a ground path through the ECM.

DIAGNOSTIC AIDS:

^ Faulty light bulb
^ Open in RED wire circuit
^ MAP sensor 5.0 volt reference shorted to ground. Engine cranks, but will not run
^ Battery feed circuit open
^ EFI main relay faulty
^ Ignition circuit open
^ Poor ECM connections