Suzuki GA413, Service Manual

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DIAGNOSIS
The engine and emission control system in this vehicle are con-
trolled by ECM. ECM has an On-Board Diagnostic system which
detects a malfunction in this system.
When diagnosing troubles, be sure to have full understanding of
the outline of “On-Board Diagnostic System” and each item in “Pre-
caution in Diagnosing Trouble” and execute diagnosis according
to “Engine Diagnostic Flow Table” in section 6.
ON-BOARD DIAGNOSTIC SYSTEM
ECM performs on-board diagnosis (self-diagnosis) on the system
and operates “CHECK ENGINE” lamp (malfunction indicator lamp)
as follows.
Malfunction indicator lamp (“CHECK ENGINE” light) lights when
the ignition switch is turned ON position (but the engine at stop)
regardless of the condition of Engine and emission control sys-
tem. This is only to check the malfunction indicator lamp
(“CHECK ENGINE” light) bulb and its circuit.
If the areas monitored by ECM is free from any trouble after the
engine start (while engine is running), malfunction indicator
lamp (“CHECK ENGINE” light) turns OFF.
When ECM detects a trouble which has occurred in the areas,
it makes malfunction indicator lamp (“CHECK ENGINE” light)
turn ON while the engine is running to warn the driver of such oc-
currence of trouble and at the same time it stores the exact
trouble area in ECM back-up memory.
PRECAUTIONS IN DIAGNOSING TROUBLES
Before identifying diagnostic trouble code, don’t disconnect cou-
plers from ECM , battery cable from battery, ECM ground wire
harness from engine. Such disconnection will erase memorized
trouble in ECM memory.
Be sure to read “Precautions for Electrical Circuit Service” in
Section 0A before inspection and observe what is written there.
ECM replacement
When substituting a known-good ECM , check for the following
conditions. Neglecting this check may cause damage to known-
good ECM .
– Resistance value of all relays, actuators is as specified re-
spectively.
– TP sensor and MAP sensor are in good condition and none of
power circuits of these sensors is shorted to ground.
ENGINE AND EMISSION CONTROL SYSTEM 6E-11