On-Board Diagnostic (Obd Ii) System Check - Isuzu 1999 RODEO Workshop Manual

ON–BOARD DIAGNOSTIC (OBD II) SYSTEM CHECK
Circuit Description
The on–board diagnostic system check is the starting
point for any driveability complaint diagnosis. Before
using this procedure, perform a careful visual/physical
check of the PCM and engine grounds for cleanliness and
tightness.
The on–board diagnostic system check is an organized
approach to identifying a problem created by an
electronic engine control system malfunction.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed–through wire insulation or a wire broken inside the
insulation. Check for poor connections or a damaged
harness. Inspect the PCM harness and connectors for
improper mating, broken locks, improperly formed or
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
damaged terminals, poor terminal–to–wire connection,
and damaged harness.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
1. The MIL ("Check Engine" lamp) should be ON
steady with the ignition ON/engine OFF. If not,
isolate the malfunction in the MIL circuit.
2. Checks the Class 2 data circuit and ensures that the
PCM is able to transmit serial data.
3. This test ensures that the PCM is capable of
controlling the MIL and the MIL driver circuit is not
shorted to ground.
4. If the engine will not start, the Cranks But Will Not
Run chart should be used to diagnose the condition.
6E1–53
D06RX036