Suzuki Grand Vitara JB627. Manual - part 69

1A-225 Engine General Information and Diagnosis: 

6

ECM ground circuit check
1) Turn ignition switch to OFF position.
2) Disconnect connectors from ECM.
3) Measure resistance between each “C37-39”, “C37-58”, 

“C37-59”, “C37-73”, “C-37-80” and “C37-81” terminals of 
ECM connector and body ground.

Is resistance 1 

Ω

 or less?

Substitute a known 
good ECM and recheck.

“BLK/ORN” or “BLK/
YEL” 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 “E23-16” terminal of ECM 

connector and measure voltage between each “E23-2” 
and “E23-3” 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 fuse box No.2.

2) Check for proper connection to main relay connector at 

“BLU/BLK” and “BLK/RED” wire terminals.

3) If OK, measure resistance between each “E23-2” and 

“E23-3” wire terminals of ECM connector and “BLU/BLK” 
wire terminal of main relay connector.

Is resistance 1 

Ω

 or less?

Go to Step 9.

“BLU/BLK” wire is open 
circuit or high resistance 
circuit.

9

Main relay circuit check
1) Remove main relay from fuse box No.2 with ignition 

switch turned OFF.

2) Measure voltage between “BLK/RED” wire terminal of 

main relay connector and body ground.

Is voltage 10 – 14 V?

Go to Step 10.

“BLK/RED” wire is open 
circuit.

10 Main relay check

1) Check main relay referring to “Engine and Emission 

Control System Relay Inspection in Section 1C”.

Is main relay in good condition?

“BLU” wire is open or 
high resistance circuit.

Replace main relay.

11 Sensor 5 V power source circuit check

1) Connect connectors to ECM with ignition switch turned 

OFF.

2) Turn ON ignition switch, measure each voltage between 

“C37-45” and “C37-49” terminal 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.

Step

Action

Yes

No

1

I5JB0C110017-01

Engine General Information and Diagnosis:  1A-226

Fuel Injector Circuit Check

S6JB0B1104086

Wiring Diagram

12 Sensor 5 V power source circuit check

1) Disconnect connectors from ECM, TP sensor, MAP 

sensor (if equipped), A/C refrigerant pressure sensor (if 
equipped) with ignition switch turned OFF.

2) Measure each resistance between “C37-45” and “C37-

49” terminal of ECM connector and vehicle body ground.

Is each resistance infinity?

Check internal short 
circuit of TP sensor, 
MAP sensor (if 
equipped) and/or A/C 
refrigerant pressure 
sensor (if equipped).

“GRY/RED” and/or 
“BLK” wire is shorted to 
ground circuit.

Step

Action

Yes

No

BLU/BLK

BLU/BLK

BLU/BLK

BLK/RED

BLK/RED

BLK/RED

BLU

12V 5V

E23-8  

E23-16
E23-2 
E23-3 

WHT/GRN

C37-59

C37-58

C37-39

C37-73

C37-80

BLK/YEL

BLK/ORN

BLK/ORN

BLK/YEL
BLK/YEL

1

3 2

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E23

C37

BLK/ORN

C37-81

BLK/YEL

BLK/WHT

C37-15

C37-34

C37-14

C37-33

C37-13

C37-32

PNK/BLK

PNK/GRN

PNK/BLU

GRY/GRN

GRY/BLK

PNK

11

10

2

3

4

5

6

7

8

9

1

13

12

P

C

C

I6JB01110010-02

P: Fuel injector power supply circuit

3. ECM

7. No.4 injector

11. Ignition switch

C: Fuel injector control circuit

4. No.1 injector

8. No.5 injector

12. “FI” fuse

1. Fuse box No.2

5. No.2 injector

9. No.6 injector

13. “IGN” fuse

2. Main relay

6. No.3 injector

10. “IG COIL” fuse

1A-227 Engine General Information and Diagnosis: 

Troubleshooting

NOTE

• Before performed troubleshooting, be sure to read the “Precautions of ECM Circuit Inspection”.
• When measuring circuit voltage, resistance and/or pulse signal at ECM connector, connect the 

special tool to ECM and/or the ECM connectors referring to “Inspection of ECM and Its Circuits”.

 

Step

Action

Yes

No

1

Fuel injector check for operating sound
1) Using sound scope, check each injector for operating 

sound at engine cranking.

Do all 6 injector make 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 terminal connection to all fuel injectors 

and ECM connector.

3) If connections are OK, check all fuel injectors 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 fuel injector connector 

power supply circuit and engine ground with ignition 
switch turned ON.

Is each voltage 10 – 14 V?

Go to Step 5.

Fuel injector power 
supply circuit is open or 
shorted to ground 
circuit.
If it is in good condition, 
go to “ECM Power and 
Ground Circuit Check”.

5

Wire harness check
1) Disconnect connector from ECM with ignition switch 

turned OFF.

2) Check that each fuel injector circuit is as follows.

• Wiring harness resistance of each fuel injector control 

circuit is less than 3 

Ω

• Insulation resistance of each fuel injector control 

circuit is infinity between each fuel injector connector 
and vehicle body ground

• Circuit voltage of each fuel injector control circuit is 0 

– 1 V with ignition switch turned ON

Are they in good condition?

Check fuel injector for 
performance referring to 
“Fuel Injector Inspection 
in Section 1G”. If OK, 
substitute a known good 
ECM and recheck.

Fuel injector control 
circuit is open, short or 
high resistance.

Engine General Information and Diagnosis:  1A-228

Fuel Pump and Its Circuit Check

S6JB0B1104087

Wiring Diagram

Troubleshooting

NOTE

• Before performed troubleshooting, be sure to read the “Precautions of ECM Circuit Inspection”.
• When measuring circuit voltage, resistance and/or pulse signal at ECM connector, connect the 

special tool to ECM and/or the ECM connectors referring to “Inspection of ECM and Its Circuits”.

 

BLU/BLK

WHT/GRN

BLU/BLK

BLU/BLK

BLK/RED

BLK/RED

BLK/RED

BLU

12V 5V

E23-8  

E23-24 

E23-16

E23-2 
E23-3 

WHT/GRN

C37-59

C37-58

C37-39

C37-73

C37-80

BLK/YEL

BLK/ORN

BLK/ORN

BLK/YEL
BLK/YEL

1

3 2

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E23

C37

BLK/ORN

C37-81

BLK/YEL

BLK/WHT

BLK/WHT

BLK/WHT

BLK

PNK

1

7

6

3

4

5

2

9

8

I6JB01110011-03

1. Fuse box No.2

3. ECM

5. Fuel pump

7. Ignition switch

9. “IGN” fuse

2. Main relay

4. Fuel pump relay

6. “IG COIL” fuse

8. “FI” fuse

Step

Action

Yes

No

1

Fuel pump control system check for operation

Is fuel pump heard to operate 2 sec. after ignition switch is 
turned ON?

Fuel pump circuit is in 
good condition.

Go to Step 2.

I2RH01110132-01