No Malfunction Indicator Lamp (Mil) - Isuzu 1999 RODEO Workshop Manual

6E1–76
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
Circuit Description
The "Check Engine" lamp (MIL) should always be
illuminated and steady with the ignition ON and the
engine stopped. Ignition feed voltage is supplied to the
MIL bulb through the meter fuse. The powertrain control
module (PCM) turns the MIL ON by grounding the MIL
driver circuit.
Diagnostic Aids
An intermittent MIL may be caused by a poor connection,
rubbed–through wire insulation, or a wire broken inside
the insulation. Check for the following items:
f Inspect the PCM harness and connections for
improper mating, broken locks, improperly formed or
damaged terminals,
connection, and damaged harness.
f 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.

NO MALFUNCTION INDICATOR LAMP (MIL)

poor terminal–to–wire
f 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 Chart:
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 B+, probe each of
the PCM ground terminals to ensure that a good
ground is present. Refer to PCM Terminal End View
for terminal locations of the PCM ground circuits.
12. In this step, temporarily substitute a known good
relay for the PCM relay. The horn relay is nearby,
and it can be verified as "good" simply by honking
the horn. Replace the horn relay after completing
this step.
D06RX038