No Malfunction Indicator Lamp (Mil); Circuit Description; Diagnostic Aids - Isuzu 2000 Trooper Workshop Manual

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 cased by a poor connection,
rubbed-through wire insulation, or a wire broken inside
the insulation. Check for the following items:
D Inspect the PCM harness and connections for
improper mating, broken locks, improperly formed or
damaged terminals,
connection, and damaged harness.
D 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.
D If the engine cranks but will not run, check for an open
PCM ignition or battery feed, or a poor PCM to engine
ground.
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

No Malfunction Indicator Lamp (MIL)

poor terminal-to-wire
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.
17.This vehicle is equipped with a PCM which utilizes
an electrically erasable programmable read only
memory (EEPROM). When the PCM is replaced,
the new PCM must be programmed. Refer to PCM
Replacement and Programming Procedures
Powertrain Control Module (PCM) and Sensors.
6E–89
D06RY00127