Ecm (Pcm) Substitution - Suzuki Engine 2002 GRAND VITARA SQ420 Service Manual

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ENGINE GENERAL INFORMATION AND DIAGNOSIS (H25 ENGINE) 6-1-41

ECM (PCM) Substitution

When substituting a known-good ECM (PCM), check for following
conditions. Neglecting this check may cause damage to known-
good ECM (PCM).
• Resistance value of all relays, actuators is as specified
respectively.
• MAP sensor and TP sensor are in good condition and none
of power circuits of these sensors is shorted to ground.
Inspection of ECM (PCM) and Its Circuits
ECM (PCM) and its circuits can be checked at ECM (PCM) wiring
couplers by measuring voltage, pulse signal and resistance.
CAUTION:
ECM (PCM) cannot be checked by itself. It is strictly pro-
hibited to connect voltmeter or ohmmeter to ECM (PCM)
with couplers disconnected from it.
Voltage Check
1) Remove ECM (PCM) cover from bracket referring to "Engine
Control Module (ECM)/Power train Control Module (PCM)" in
Section 6E2.
2) Check voltage at each terminal of couplers connected, using
voltmeter (1) or oscilloscope (2).
NOTE:
• As each terminal voltage is affected by the battery volt-
age, confirm that it is 11 V or more when ignition
switch is ON.
• Voltage with asterisk (
meter because it is pulse signal.
✱
) can not be measured by volt-