2008 SUZUKI SWIFT isc

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Inspection of ECM and Its CircuitsS7RS0B1104079
ECM and its circuits can be checked by measuring voltage, pulse signal and resistance with special tool connected.
CAUTION!
ECM cannot be checked by itself. It is strictly prohibited to connect voltmeter or ohmmeter to ECM
with ECM connectors disconnected from it.

Voltage Check
1) Remove ECM (1) from its bracke t referring to “ECM Removal and Installation in Section 1C”.
2) Connect special tool between EC M and ECM connectors securely.
Special tool
(A): 09933–06320
3) Check voltage and/or pulse signal us ing voltmeter (2) and oscilloscope (3).
NOTE
• As each terminal voltage is affected by battery voltag e, confirm that it is 11 V or more when ignition
switch is turned ON.
• Voltage with asterisk (*) cannot be measured with voltmeter because it is pulse signal. Use oscilloscope for its check if necessary.
• Before this inspection, be sure to read the “Precautions of ECM Circuit Inspection”.

Viewed from harness side
1
2
3 (A)
I5RS0C110023-01
E23
C37
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 4832 31
34353637
40
42 39 38
44
45 43 41 331
1213
238
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 4832 31
34353637
40
42 39 38
44
45 43 41 331
1213
238
I4RS0A110055-01

Downloaded from www.Manualslib.com manuals search engine 1A-178 Engine General Information and Diagnosis:
C37-20RED/
YEL CMP sensor signal 0 – 1 V or 4 – 5 V Ignition switch turned ON. —
*0 – 0.6 V↑↓
4 – 5 V
(“Reference
waveform No.16: ” and “Reference
waveform No.17: ”) Engine running at idle
after warmed up engine.
Sensor signal is pulse.
Pulse frequency varies
depending on engine
speed.
(6 pulses are generated
per 1 camshaft revolution.)
C37-21 PNK CKP sensor signal 0 – 1 V or 4 – 5 V Ignition switch turned ON. —
*4 – 5 V↑↓
0 – 0.6 V
(“Reference
waveform No.16: ” and “Reference
waveform No.17: ”) Engine running at idle
after warmed up engine. Sensor signal is pulse.
Pulse frequency varies
depending on engine
speed.
(30 (36 – 6) pulses are
generated per 1
crankshaft revolution.)
C37-22 — — — — —
C37-23 PNK/
BLU Electric load
current sensor
signal 3.8 – 4.2 V Ignition switch turned ON.
—
3.0 – 3.4 V
Ignition switch turned ON
and headlight switch
turned ON (HI beam).
2.3 – 2.7 V Ignition switch turned ON,
headlight switch turned
ON (HI beam) and blower
selector at HI position.
C37-24 LT GRN ECT sensor signal 3.3 – 3.8 V
Ignition switch turned ON,
ECT at 0
°C, 32 °F.
—
1.38 – 1.72 V Ignition switch turned ON,
ECT at 50
°C, 122 °F.
0.40 – 0.53 V Ignition switch turned ON,
ECT at 100
°C, 212 °F.
C37-25 BLK/
YEL IAT sensor signal 3.18 – 3.67 V
Ignition switch turned ON,
IAT at 0
°C, 32 °F.
—
1.32 – 1.65 V Ignition switch turned ON,
IAT at 40
°C, 104 °F.
0.46 – 0.60 V Ignition switch turned ON,
IAT at 80
°C, 176 °F.
C37-26 GRN/
BLK MAF sensor signal 0.5 – 1.5 V
Ignition switch turned ON
with engine at stop.
—
1.5 – 2.0 V
(“Reference
waveform No.18: ”) Wh

en engine running at
specified idle speed after
warmed up.
C37-27 GRY Ground for MAF
sensor Below 0.3 V Ignition switch turned ON.
—
C37-28 BLU/
YEL Generator control
signal output *0 – 0.6 V
↑↓
5 – 8 V
(“Reference
waveform No.19: ”) Engine running at idle
speed, headlight switch
turned ON.
Output signal is active low
duty pulse. Duty ratio
varies depending on
vehicle condition.
C37-29 BLU/
BLK EVAP canister
purge valve output 10 – 14 V
Ignition switch turned ON
with engine at stop. —
*0 – 0.6 V ↑↓
10 – 14 V
(“Reference
waveform No.20: ”) Set EVAP canister purge
valve at 52% by using
“Misc Test” of scan tool.
Output signal is active low
duty pulse. Duty ratio
varies depending on
vehicle condition.
C37-30 BLK Ground for ECM Below 0.3 V Ignition switch turned ON. —
C37-31 — —— — —
Terminal
No. Wire
color Circuit Normal voltage
ConditionRemarks

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Reference waveform No.18
MAF sensor signal (1) with engine racing
Reference waveform No.19
Generator control signal (1) at engine idlingReference waveform No.20
EVAP canister purge valve signal
Measurement
terminal CH1: “C37-26” to “C37-27”
CH2: “C37-54” to “C37-55”
Oscilloscope
setting CH1: 1 V/DIV, CH2: 1 V/DIV
TIME: 200 ms/DIV
Measurement
condition • After warmed up to normal
operating temperature
• Engine racing
2. TP sensor signal
3. Racing
4. Idle
Measurement
terminal CH1: “C37-28” to “C37-58”
Oscilloscope
setting CH1: 5 V/DIV
TIME: 10 ms/DIV
Measurement
condition • After warmed up to normal
operating temperature
• Engine at specified idle speed
• For a few sec. from headlight switch turned ON
I4RS0B110066-01
I7RS0B110015-01
Measurement
terminal CH1: “C37-29” to “C37-58”
Oscilloscope
setting CH1: 10 V/DIV
TIME: 40 ms/DIV
Measurement
condition • After warmed up to normal
operating temperature
• EVAP canister purge valve setting at 52% by using “Misc Test” of
scan tool
1. ON signal
2. OFF signal
3. One duty cycle
4. 10 – 14 V
I4RS0B110067-01

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-193
Reference waveform No.32
VSS signal at 30 km/h (19 mph)
Resistance Check1) Remove ECM from its bracket referring to “ECM Removal and Installation in Section 1C”.
CAUTION!
Never touch terminals of ECM itself or connect voltmeter or ohmmeter (2).

2) Connect special tool to ECM connectors securely.
NOTE
Do not connect the other connector of special tool to ECM.

3) Check resistance between each pair of terminals of disconnected connectors (1) as listed in the following table.
CAUTION!
• Be sure to connect ohmmeter probe from wire harness side of coupler.
• Be sure to turn OFF ignition switch for this check.
• Resistance in the following table represents that measured when parts temperature is 20 °C (68 °F).

Measurement
terminal CH1: “E23-25” to “C37-58”
Oscilloscope
setting CH1: 5 V/DIV, CH2: 5 V/DIV
TIME: 40 ms/DIV
Measurement
condition • After warmed up to normal
operating temperature
• Vehicle driving at 30 km/h (19 mph)
1. VSS signal for EPS control module
2. ON
3. OFF
I6RS0C110047-01
1
2
I4RS0A110086-02
Terminals CircuitStandard resistance Condition
C37-47 to E23-29 Heater of HO2S-2 4 – 15 Ω—
E23-46 to E23-1/16 Radiator cooling fan relay No.1 160 – 240 Ω —
E23-60 to E23-29 Main relay 160 – 240 ΩBattery disconnected
and ignition switch
turned ON
E23-15 to E23-29 Fuel pump relay 160 – 240 Ω —
C37-16 to E23-1/16 No.3 fuel injector 10.8 – 18.2 Ω —
C37-17 to E23-1/16 No.4 fuel injector
C37-4 to E23-1/16 EGR valve (st epping motor No.1 coil) 20 – 31 Ω —
C37-29 to E23-1/16 EVAP canister purge valve 28 – 35 Ω —
C37-2 to E23-1/16 No.2 fuel injector 10.8 – 18.2 Ω—

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-195
Circuit Description
When the ignition switch is turned ON, the main relay turns ON (the contact point closes) and the main power is
supplied to ECM.
Troubleshooting
NOTE
When measuring circuit voltage, resistance and/or pulse signal at ECM connector, connect the special
tool to ECM and/or the ECM connectors referri ng to “Inspection of ECM and Its Circuits”.

StepAction YesNo
1 Circuit fuse check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Check for proper connection to ECM connector at “E23- 2”, “E23-29”, “E23-60”, “E23-1”, “E23-16”, “E23-31”,
“C37-58”, “C37-15” and “C37-30” terminals.
3) If OK, check “RADIO” fuse and “IG COIL” fuse for blowing.
Are “RADIO” fuse and “IG COIL” fuse in good condition? Go to Step 2.
Replace fuse (s) and
check for short in
circuits connected to
fuse(s).
2 Power supply circuit check
1) Measure voltage between “E23-2” terminal of ECM
connector and body ground.
Is voltage 10 – 14 V? Go to Step 3.
“WHT/RED” or “WHT”
wire is open circuit.
3 Ignition signal check
1) Turn ignition switch to ON position.
2) Measure voltage between “E23-29” terminal of ECM
connector and body ground.
Is voltage 10 – 14 V? Go to Step 4.
“BLK/WHT” or “GRN”
wire is open circuit.
4 Main relay circuit check
1) Turn ignition switch to OFF position.
2) Check “FI” fuse (1) in indivi dual circuit fuse box No.1 for
blowing.
3) If OK, measure voltage between “E23-60” terminal of ECM connector and body ground.
Is voltage 10 – 14 V? Go to Step 5.
Go to Step 9.
1
I4RS0A110016-01

Downloaded from www.Manualslib.com manuals search engine 1A-196 Engine General Information and Diagnosis:
5Main relay circuit check
1) Connect connectors to ECM with ignition switch turned
OFF.
2) Turn ignition switch to ON position.
3) Measure voltage between “E23-60” terminal of ECM connector and body ground.
Is voltage 0 – 1 V? Go to Step 7. Go to Step 6.
6 ECM ground circuit check
1) Turn ignition switch to OFF position.
2) Disconnect connectors from ECM.
3) Measure resistance between each “E23-31”, “C37-58”,
“C37-15” and “C37-30” terminals of ECM connector and
body ground.
Is resistance 1
Ω or less? Substitute a known-
good ECM and recheck.
“BLK/ORN” or “BLK”
wire is open or high
resistance circuit.
7 Main relay circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Using service wire, ground “E23-60” terminal of ECM connector and measure voltage between each “E23-1”
and “E23-16” terminals of ECM connector and body
ground.
Is voltage 10 – 14 V? Go to Step 11. Go to Step 8.
8 Main relay circuit check
1) Remove main relay (1) from individual circuit fuse box
No.1.
2) Check for proper connection to main relay connector at “BLK/YEL” and “BLK/RED” wire terminals.
3) If OK, measure resistance between each “E23-1” and “E23-16” wire terminals of ECM connector and “BLK/
RED” wire terminal of main relay connector.
Is resistance 1
Ω or less? Go to Step 9. “BLK/RED” wire is open
circuit or high resistance
circuit.
9 Main relay circuit check
1) Remove main relay from individual circuit fuse box No.1
with ignition swit ch turned OFF.
2) Measure voltage between “BLK/YEL” wire terminal of main relay connector and body ground.
Is voltage 10 – 14 V? Go to Step 10. “BLK/YEL” wire is open
circuit.
Step Action Yes No
1
I4RS0A110017-01

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-197
10Main relay check
1) Check main relay referring to “Main Relay, Fuel Pump
Relay and Starting Motor Control Relay Inspection in
Section 1C”.
Is main relay in good condition? “BRN/WHT” wire is
open or high resistance
circuit.
Replace main relay.
11 Sensor power source circuit check
1) Connect connectors to ECM with ignition switch turned
OFF.
2) Turn ON ignition switch, measure each voltage between “C37-14”, “E23-35”, “E23-34” and “C37-43” terminals of
ECM connector and vehicle body ground.
Is each voltage 4 – 6 V? ECM power and ground
circuit is in good
condition.
Go to Step 12.
12 Sensor power source circuit check
1) Disconnect connectors from ECM, TP sensor, APP
sensor, MAP sensor and A/C refrigerant pressure sensor
(if equipped with A/C) with i gnition switch turned OFF.
2) Measure each resistance between “C37-14”, “E23-35”, “E23-34” and “C37-43” terminals of ECM connector and
vehicle body ground.
Is each resistance infinity? Check internal short
circuit of TP sensor,
APP sensor, MAP
sensor and/or A/C
refrigerant pressure
sensor (if equipped with
A/C).
“GRY/RED” wire is
shorted to ground
circuit.
Step Action Yes No

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-199
Troubleshooting
NOTE
When measuring circuit voltage, resistance and/or pulse signal at ECM connector, connect the special
tool to ECM and/or the ECM connectors referri ng to “Inspection of ECM and Its Circuits”.

StepAction YesNo
1 Fuel injector check for operating sound
1) Using sound scope, check each injector for operating
sound at engine cranking.
Do all 4 injector ma ke operating sound? Fuel injectors circuit is
in good condition.
Go to Step 2.
2 Fuel injector resistance check
1) Disconnect connectors from fuel injectors with ignition
switch turned OFF.
2) Check for proper connection to fuel injector at each terminals.
3) If OK, check all 4 fuel inject ors for resistance referring to
“Fuel Injector On-Vehicle Inspection in Section 1G”.
Are all injectors in good condition? Go to Step 3.
Faulty fuel injector.
3 Fuel injector insulation resistance check
1) Check that there is insulation between each fuel injector
terminal and engine ground.
Is there insulation? Go to Step 4.
Faulty fuel injector.
4 Fuel injector power supply check
1) Measure voltage between each “BLK/RED” wire terminal
of fuel injector connector and engine ground with ignition
switch turned ON.
Is voltage 10 – 14 V? Go to Step 5.
“BLK/RED” wire is open
or shorted to ground
circuit.
If it is in good condition,
go to “ECM Power and
Ground Circuit Check”.
5 Wire circuit check
1) Turn OFF ignition switch.
2) Disconnect connectors from ECM.
3) Measure resistance between each “BLU/YEL”, “BLU/
WHT”, “BLU/RED”, “BLU/ORN” wire terminal of fuel
injector connector and vehicle body ground.
Is resistance infinity? Go to Step 6.
“BLU/YEL”, “BLU/WHT”,
“BLU/RED” and/or
“BLU/ORN” wire(s) are
shorted to ground.
6 Wire circuit check
1) Measure voltage between each “BLU/YEL”, “BLU/WHT”,
“BLU/RED”, “BLU/ORN” wire terminal of fuel injector
connector and vehicle body ground with ignition switch
turned ON.
Is voltage 0 V? Go to Step 7.
“BLU/YEL”, “BLU/WHT”,
“BLU/RED” and/or
“BLU/ORN” wire(s) are
shorted to power supply
circuit.
7 Fuel injector drive signal check
1) Connect connectors to each fuel injector and ECM with
ignition switch turned OFF.
2) Turn ON ignition switch.
3) Measure voltage between each “C37-1”, “C37-2”, “C37- 16”, “C37-17” terminal of ECM connector and vehicle
body ground.
Is voltage 10 – 14 V? Check fuel injector
referring to “Fuel
Injector Inspection in
Section 1G”.
If check result is
satisfactory, substitute a
known-good ECM and
recheck.
“BLU/YEL”, “BLU/WHT”,
“BLU/RED” and/or
“BLU/ORN” wire(s) are
open circuit.