Suzuki Grand Vitara JB416 / JB420 / JB419. Manual - part 55

1A-167 Engine General Information and Diagnosis: For Petrol Engine Model

DTC P0620: Generator Control Circuit

S6JB0A1114058

System and Wiring Diagram

Generator Control System Description
Refer to “Generator Control System Description: For Petrol Engine Model”.

DTC Detecting Condition and Trouble Area

DTC Confirmation Procedure

1) With ignition switch turned OFF, connect scan tool to DLC
2) Turn ON ignition switch and clear DTC.
3) Make sure that all accessory switches are tuned OFF.
4) Start engine and warm it up to normal operating temperature (ECT approx. 90 – 95 

°C, 193 – 203 °F).

5) Turn ON the following accessory switches.

• Head light switch.
• Blower motor switch (max position).
• Rear defogger switch.

6) Increase engine speed to 4000 rpm and keep it for 10 sec or more.
7) Decrease engine speed to idle.
8) Check DTC and pending DTC.

IG

L

C

FR

E

4

2

BRN/BLK

C37-8

BRN/BLK

C37-28

B

E23

C37

3

4

18

19

5

6

7

10

11

17

20

47

46

49

50

51

21

22

52

16

25

9

24

14
29

55

57

54 53

59

60

58

2

26

27

28

15
30

56

48

32

31

34

35

36

37

40

42

39 38

44

45

43

41

33

1

12

13

23

8

3

4

18

19

5

6

7

10

11

17

20

47

46

49

50

51

21

22

52

16

25

9

24

14
29

55

57

54 53

59

60

58

2

26

27

28

15
30

56

48

32

31

34

35

36

37

40

42

39 38

44

45

43

41

33

1

12

13

23

8

1

3

5

I5JB0A110063-01

1. Generator

3. Field coil

5. Ignition switch

2. IC regulator

4. ECM

6. Charge lamp

DTC detecting condition

Trouble area

• Battery voltage is higher than 14 V even through generator 

control is maximum regulation (duty 100%).

• Battery voltage is lower than 12.5 V even through generator 

control is minimum regulation (duty 50%) and electric load is 
less than 20 A.

Generator and/or its circuit
Electric load current sensor (for J20 engine)
ECM

Engine General Information and Diagnosis: For Petrol Engine Model 1A-168

DTC Troubleshooting

NOTE
Before this trouble shooting is performed, read the precautions for DTC troubleshooting referring to 
“Precautions for DTC Troubleshooting: For Petrol Engine Model”.

 

Step

Action

Yes

No

1

Was “Engine and Emission Control System Check” 
performed?

Go to Step 2.

Go to “Engine and 
Emission Control 
System Check: For 
Petrol Engine Model”.

2

Generator control circuit check
1) Disconnect connector from generator and ECM with 

ignition switch turned OFF.

2) Check for proper connection of wire terminal to 

generator connector and to ECM connector.

3) If connections are OK, check generator control circuit for 

the following.
• Resistance of generator control circuit wire between 

generator connector and ECM connector is less than 
1 

Ω (continuity check)

• Resistance between generator control circuit wire of 

generator connector and vehicle body ground is 
infinity (ground circuit short check)

• Voltage between generator control circuit wire of 

generator connector and vehicle body ground is 0 V 
with ignition switch tuned ON (power circuit short 
check)

Are they in good condition?

Go to Step 3.

Repair or replace 
defective wire.

3

Generator check
1) Check for generator output referring to “Generator Test 

(Undercharged Battery Check): For Petrol Engine Model 
in Section 1J”.

Is check result satisfactory?

For J20 engine, go to 
Step 4.
For M16 engine, 
Substitute a known 
good ECM and recheck.

Repair or replace 
generator.

4

Electric load current sensor check (for J20 engine)
1) Check for electric load current sensor output referring to 

“Electric Load Current Sensor On-Vehicle Inspection 
(For J20 Engine): For Petrol Engine Model in Section 
1C”.

Is check result satisfactory?

Substitute a known 
good ECM and recheck.

Replace electric load 
current sensor.

1A-169 Engine General Information and Diagnosis: For Petrol Engine Model

DTC P0625 / P0626: Generator Field Terminal Circuit Low / High

S6JB0A1114059

System and Wiring Diagram
Refer to “DTC P0620: Generator Control Circuit: For Petrol Engine Model”.

Generator Control System Description
Refer to “Generator Control System Description: For Petrol Engine Model”.

DTC Detecting Condition and Trouble Area

DTC Confirmation Procedure

1) With ignition switch turned OFF, connect scan tool to DLC.
2) Turn ON ignition switch and clear DTC.
3) Make sure that all accessory switch is tuned OFF.
4) Start engine and warm it up to normal operating temperature (ECT approx. 90 – 95 

°C, 193 – 203 °F).

5) Turn ON following accessory switch.

• Head lights switch.
• Blower motor switch (max position).
• Rear defogger switch.

6) Increase engine speed to 4000 rpm and keep it for 10 sec. or more.
7) Decrease engine speed to idle.
8) Check DTC and pending DTC.

DTC detecting condition

Trouble area

P0625:
Generator field coil duty is 100% (low voltage) for more than 
specified time even through generator control is maximum 
regulation (control duty 100%) or Generator field coil duty is 100% 
(low voltage) when engine is starting.
P0626:
Generator field coil duty is 0% (high voltage) for more than 
specified time even through generator control is minimum 
regulation (control duty 0%).

Generator and/or its circuit
ECM

Engine General Information and Diagnosis: For Petrol Engine Model 1A-170

DTC Troubleshooting

NOTE
Before this trouble shooting is performed, read the precautions for DTC troubleshooting referring to 
“Precautions for DTC Troubleshooting: For Petrol Engine Model”.

 

Step

Action

Yes

No

1

Was “Engine and Emission Control System Check” 
performed?

Go to Step 2.

Go to “Engine and 
Emission Control 
System Check: For 
Petrol Engine Model”.

2

Generator control circuit check
1) Disconnect connector from generator and ECM with 

ignition switch turned OFF.

2) Check for proper connection of wire terminal to 

generator connector and to ECM connector.

3) If connections are OK, check generator control 

(generator “C” terminal) circuit and field coil monitor 
(generator “FR” terminal) circuit for the following.
• Resistance of each generator control wire and field 

coil monitor wire between generator connector and 
ECM connector is less than 1 

Ω (continuity check)

• Resistance between generator control wire and field 

coil monitor wire of generator connector is infinity 
(insulation check)

• Resistance between each generator control wire and 

field coil monitor wire of generator connector and 
vehicle body ground is infinity (ground circuit short 
check)

• Voltage between each generator control wire and field 

coil monitor wire of generator connector and vehicle 
body ground is 0 V with ignition switch tuned ON 
(power circuit short check)

Are they in good condition?

Go to Step 3.

Repair or replace 
defective wire.

3

Generator check
1) Check for generator output referring to “Generator Test 

(Undercharged Battery Check): For Petrol Engine Model 
in Section 1J” and “Generator Inspection: For Petrol 
Engine Model in Section 1J”.

Is check result satisfactory?

Substitute a known 
good ECM and recheck.

Repair or replace 
generator.