Suzuki Grand Vitara JB416 / JB420. Manual - part 72

1A-237 Engine General Information and Diagnosis:

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. And then ECM supplies 5 V power to each sensor (electric load current sensor (for J20 engine),
MAP sensor, A/C refrigerant pressure sensor, APP sensor and TP sensor).
If 5 V power circuit to each sensors from ECM is shorted to ground, ECM stops engine and emission control operation.

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

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”, “C37-15”,
“C37-30”, “C37-29”, “C37-48” and “C37-58” terminals.

3) If OK, check “RADIO” fuse and “IG COIL” fuse for

blowing.

Are “DOME” 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).

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” wire is open
circuit.

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 “BLK/
YEL” wire is open
circuit.

Engine General Information and Diagnosis: 1A-238

Main relay circuit check
1) Turn ignition switch to OFF position.
2) Check “FI” fuse (1) (20 A) in fuse box No.2 for blowing.

For J20 engine

For M16 engine

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.

Main 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.

ECM ground circuit check
1) Turn ignition switch to OFF position.
2) Disconnect connectors from ECM.
3) Measure resistance between each “C37-15”, “C37-30”,

“C37-29”, “C37-48” and “C37-58” 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.

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.

Step

Action

Yes

I5JB0A110097-02

I5JB0A110098-02

1A-239 Engine General Information and Diagnosis:

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

For J20 engine

For M16 engine

2) Check for proper connection to main relay connector at

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

3) If OK, measure resistance between each “E23-1” and

“E23-16” 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.

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 “Control 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

“C37-14”, “E23-56”, “E23-53” and “C37-53” 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

I5JB0A110099-02

I5JB0A110100-02

Engine General Information and Diagnosis: 1A-240

Fuel Injector Circuit Check

S5JB0A1104065

Wiring Diagram

12 Sensor 5 V power source circuit check

1) Disconnect connectors from ECM, TP sensor, MAP

sensor, A/C refrigerant pressure sensor (if equipped with
A/C), electric load current sensor (for J20 engine) and
accelerator pedal position (APP) sensor with ignition
switch turned OFF.

2) Measure each resistance between “C37-14”, “E23-56”,

“E23-54” and “C37-53” terminal of ECM connector and
vehicle body ground.

Is each resistance infinity?

Check internal short
circuit of TP sensor,
MAP sensor, A/C
refrigerant pressure
sensor (if equipped with
A/C), electric load
current sensor (for J20
engine) and/or
accelerator pedal
position (APP) sensor.

“GRY/RED”, “WHT”
and/or “ORN/BLU” wire
is shorted to ground
circuit.

Step

Action

Yes

BLK/WHT

BLU/BLK

WHT/GRN

BLK/RED

BLK/YEL

BLU

12V

E23-29

E23-1

E23-60

E23

C37

14
29

54 53

15
30

39 38

14
29

54 53

15
30

39 38

C37-1

C37-2

C37-16

C37-17

BLU/BLK

PNK

PNK/GRN

PNK/BLU

PNK/BLK

E23-16

C37-15

C37-29
C37-48

BLK/ORN

C37-58

C37-30 BLK/ORN

BLK/YEL
BLK/YEL
BLK/YEL

I5JB0A110101-01

1. Fuse box No.2

4. No.1 injector

7. No.4 injector

10. “FI” fuse

2. Main relay

5. No.2 injector

8. “IG COIL” fuse

11. “IGN” fuse

3. ECM

6. No.3 injector

9. Ignition switch

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