Suzuki GRAND VITARA Owner's Manual page 179

Step
1 Was "Engine and Emission Control System Check"
performed?
2 Knock sensor circuit check
1) Remove ECM from its bracket with ECM connectors
connected.
2) Measure voltage between "C37-56" terminal of ECM
connector and vehicle body ground with engine running.
Is voltage within 1.23 – 3.91 V?
3 Knock sensor circuit for open check
1) Disconnect connector from knock sensor with ignition
switch turned OFF.
2) Turn ON ignition switch, measure voltage between
"WHT" wire of knock sensor connector and engine
ground.
Is voltage 4 – 6 V?
4 Knock sensor circuit for open check
1) Turn ON ignition switch, measure voltage between "C37-
56" terminal of ECM connector and engine ground
Is voltage 4 – 6 V?
5 Knock sensor circuit for short check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between "C37-56" terminal of ECM
connector and vehicle body ground.
Is resistance infinity?
6 Knock sensor circuit for short check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Turn ON ignition switch, measure voltage between "C37-
56" terminal of ECM connector and vehicle body ground.
Is voltage 0 V?
7 Knock sensor circuit for high resistance check
1) Turn OFF ignition switch, measure resistance between
"C37-56" terminal of ECM connector and "RED" wire
terminal of knock sensor harness connector.
Is resistance below 5
Action
Ω
?
Engine General Information and Diagnosis:
Yes
Go to Step 2.
Intermittent trouble.
Check for intermittent
referring to "Intermittent
and Poor Connection
Inspection: in Section
00". If OK, substitute a
known-good ECM and
recheck.
Go to Step 6.
I2RH01110089-01
"WHT" wire is open
circuit.
Go to Step 6.
Go to Step 7.
Faulty knock sensor.
1A-124
No
Go to "Engine and
Emission Control
System Check: ".
Go to Step 3.
Go to Step 4.
Go to Step 5.
"WHT" wire is shorted to
ground circuit.
If wire is OK, substitute
a known-good ECM and
recheck.
"WHT" wire is shorted to
other circuit.
"WHT" wire is high
resistance circuit.