Fig. 82: Identifying EGR System Module Components & Circuits (2 Of 2)
Courtesy of FORD MOTOR CO.
SELF-DIAGNOSTIC SYSTEM
MALFUNCTION INDICATOR LIGHT
Malfunction Indicator Light (MIL) alerts the driver that PCM has detected an OBD-II emission related
component or system fault. When this occurs, an OBD-II DTC will be set. MIL is located on instrument cluster
and is labeled CHECK ENGINE, SERVICE ENGINE SOON or uses an ISO standard engine symbol. See Fig.
83 . Power is supplied to MIL whenever ignition switch is in RUN or START position. MIL will remain ON in
RUN or START mode as a bulb check during instrument cluster proveout for about 4 seconds. MIL will remain
on after bulb check for the following reasons:
z
PCM illuminates MIL for an emission related concern and a DTC will be present.
z
Instrument cluster will illuminate MIL if PCM does not send a control message to instrument cluster.
z
PCM is operating in Hardware Limited Operation Strategy (HLOS). See HARDWARE LIMITED
OPERATION STRATEGY under POWERTRAIN CONTROL MODULE under COMPUTERIZED
ENGINE CONTROLS.
z
MIL circuit is shorted to ground.
If MIL remains off (during bulb check), possible causes are; bulb is damaged or MIL circuit is open. To turn off
the MIL after a repair, a reset command from scan tool must be sent, or 3 consecutive drive cycles must be
completed without a fault. If MIL blinks at a steady rate, a severe misfire condition could possibly exist. If MIL
blinks erratically, an intermittent open in B+ circuit to bulb or an intermittent short to ground in MIL circuit
may exist. Also, PCM can reset while cranking if battery voltage is low.
NOTE:
All systems have self-diagnostic capabilities. For information on procedures for
entering self-test modes and reading diagnostic trouble codes, see SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.
2003 Ford Pickup F150
2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline