Chart A-1 No Malfunction Indicator Lamp (MIL)

Chart A-1 No MIL Service Engine Soon Light:

Chart A-1:

CIRCUIT DESCRIPTION
When the ignition switch is turned "ON" (engine "OFF") except for a brief flash, the Malfunction Indicator Lamp (MIL) should remain "ON."
Battery voltage is applied directly to the lamp via the GAUGES fuse (Instrument fuse block) through the ignition switch. The Powertrain Control Module (PCM) provides the ground for the MIL when the ignition is "ON," and engine "OFF"

CHART TEST DESCRIPTION
1. If the GAUGES fuse is blown, all the other dash lamps would not function.
2. Using a test light connected to B+ (battery voltage), probe each of the system ground circuits to be sure a good ground is present.

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

1. If the fusible link or fuse is blown, locate and repair short to ground.
2. Using a test light connected to 12 volts, probe each of the system ground circuits to be sure a good ground is present.

DIAGNOSTIC AIDS
If the engine runs OK, check:
^ Faulty light bulb.
^ Circuit 419 open.
^ GAUGES fuse blown. This will result in loss of MIL, Oil lamp. brake light on Instrument Panel (I/P).

If the engine cranks but will not run.
^ Continuous battery - fuse or fusible link open.
^ PCM ignition feed fuse open.
^ Battery circuit 2 to PCM open.
^ Ignition feed circuit 639 to PCM open.
^ Poor PCM ground.