Suzuki Grand Vitara JB416 / JB420. Manual - part 233

5A-66 Automatic Transmission/Transaxle: 

DTC P1777: TCM Lost Communication with ECM (Reception Error)

S5JB0A5104058

Wiring Diagram
Refer to “DTC P1774: CAN Communication Bus Off”.

DTC Detecting Condition and Trouble Area

DTC Confirmation Procedure

1) Connect scan tool to DLC with ignition switch turned OFF.
2) Turn ON ignition switch and clear DTC by using scan tool.
3) Start engine and run it for 1 min. or more.
4) Check DTC and pending DTC.

DTC Troubleshooting

NOTE
Upon completion of inspection and repair work, perform “DTC Confirmation Procedure: ” and confirm 
that the trouble has been corrected.

 

DTC Detecting Condition

Trouble Area

Reception error of communication data for ECM is detected for 
longer than specified time continuously.
(1 driving cycle detection logic)

• ECM
• ABS hydraulic unit / control module
• TCM
• CAN communication line circuit

Step

Action

Yes

No

1

Was “A/T System Check” performed?

Go to Step 2.

Go to “A/T System 
Check”.

2

Control module connector check
1) Check connection of connectors of all control modules 

communicating by means of CAN.

2) Recheck DTC in TCM referring to “DTC Check”.

Is there DTC P1777?

Go to Step 3.

Intermittent trouble. 
Check for intermittent 
referring to “Intermittent 
and Poor Connection 
Inspection in Section 
00”.

3

DTC check in ABS hydraulic unit / control module
1) Check DTC in ABS hydraulic unit / control module.

Is there DTC U1100?

Go to Step 4.

Go to Step 5.

4

DTC check
1) Check DTC in ECM referring to “DTC Check in Section 

1A”.

Is there DTC P1674?

Go to “DTC P1674: 
CAN Communication 
(Bus Off Error) in 
Section 1A”.

Check ECM power and 
ground circuit. If circuit 
is OK, CAN 
communication circuit 
between ECM and ABS 
hydraulic unit / control 
module is open circuit.

5

CAN communication circuit check
1) Turn ignition switch to OFF position.
2) Disconnect connectors of all control modules 

communicating by means of CAN.

3) Check CAN communication circuit between control 

modules for open, short and high resistance.

Is each CAN communication circuit in good condition?

Check TCM power and 
ground circuit. If circuit 
is OK, substitute a 
known-good TCM and 
recheck.

Repair circuit.

Automatic Transmission/Transaxle:  5A-67

DTC P1778: TCM Lost Communication with BCM (Reception Error)

S5JB0A5104059

Wiring Diagram
Refer to “DTC P1774: CAN Communication Bus Off”.

DTC Detecting Condition and Trouble Area

DTC Confirmation Procedure

1) Connect scan tool to DLC with ignition switch turned OFF.
2) Turn ON ignition switch and clear DTC by using scan tool.
3) Start engine and run it for 1 min. or more.
4) Check DTC and pending DTC.

DTC Troubleshooting

NOTE
Upon completion of inspection and repair work, perform “DTC Confirmation Procedure: ”“DTC 
Confirmation Procedure” and confirm that the trouble has been corrected.

 

DTC Detecting Condition

Trouble Area

Reception error of communication data for BCM is detected for 
longer than specified time continuously.
(1 driving cycle detection logic)

• BCM
• TCM
• CAN communication line circuit

Step

Action

Yes

No

1

Was “A/T System Check” performed?

Go to Step 2.

Go to “A/T System 
Check”.

2

Control module connector check
1) Check connection of connectors of all control modules 

communicating by means of CAN.

2) Recheck DTC in TCM referring to “DTC Check”.

Is there DTC P1778?

Go to Step 3.

Intermittent trouble. 
Check for intermittent 
referring to “Intermittent 
and Poor Connection 
Inspection in Section 
00”.

3

DTC check in BCM (bus off)
1) Check DTC in BCM referring to “DTC Check in Section 

10B”.

Is there DTC U1073?

Go to “DTC U1073 (No. 
1073): Control Module 
Communication Bus Off 
in Section 10B”.

Go to Step 4.

4

DTC check
1) Check DTC in ECM referring to “DTC Check in Section 

1A”.

Is there DTC P1678?

Check BCM power and 
ground circuit. If circuit 
is OK, substitute a 
known-good BCM and 
recheck.

Go to Step 5.

5

CAN communication circuit check
1) Turn ignition switch to OFF position.
2) Disconnect connectors of all control modules 

communicating by means of CAN.

3) Check CAN communication circuit between control 

modules for open, short and high resistance.

Is each CAN communication circuit in good condition?

Check TCM power and 
ground circuit. If circuit 
is OK, substitute a 
known-good TCM and 
recheck.

Repair circuit.

5A-68 Automatic Transmission/Transaxle: 

DTC P1874: 4L Switch Circuit Malfunction (Short)

S5JB0A5104047

Wiring Diagram

DTC Detecting Condition and Trouble Area

DTC Confirmation Procedure

1) Connect scan tool to DLC with ignition switch OFF.
2) Clear DTCs in TCM and ECM memories by using scan tool.
3) Start engine and transfer position switch to “4H” position.
4) Keep engine running at idle speed for 10 seconds or more with select lever “D” range.
5) Start vehicle and increase vehicle speed to about 60 km/h (37 mile/h) for 2 minutes.
6) Stop vehicle.
7) Check DTC, pending DTC and freeze frame data.

DTC Troubleshooting

12V

12V

PNK/WHT

BLK

E93-4

1

2

4

3

6

5

16 15 14 13 12 11

4 3

24 23

21

22

10 9

8

7

2

1

19

20

18 17

E92

17 16

26 25

15 14

6

5

3

4

2

13 12

23 22

24

11 10 9

21 20 19

8 7

18

1

E93

I5JB0A510026-01

1. 4L/N switch

3. 4WD control module

2. TCM

4. Terminal arrangement of TCM connector (viewed from harness side)

DTC Detecting Condition

Trouble Area

Actual transfer position is 4H although TCM detected 4L/N switch 
is turned ON with vehicle speed between 29 km/h (18 mile/h) and 
88 km/h (55 mile/h).
(1 driving cycle detection logic)

• 4L/N switch or its circuit.
• TCM

Step

Action

Yes

No

1

Vehicle speed signal check
1) Check DTC in ECM and ABS hydraulic unit / control 

module referring to “DTC Check in Section 1A” or “DTC 
Check in Section 4E”.

Is there DTC P P0500: Vehicle speed sensor (VSS) 
malfunction in ECM and/or DTC C1021, C1022, C1025, 
C1026, C1031, C1032, C1035 and/or C1036 in ABS 
hydraulic unit / control module?

Go to applicable DTC 
diag. flow.

Go to Step 2.

2

Was “A/T System Check” performed?

Go to Step 2.

Go to “A/T System 
Check”.

3

Do you have SUZUKI scan tool?

Go to Step 4.

Go to Step 5.

Automatic Transmission/Transaxle:  5A-69

DTC P1875: 4L Switch Circuit Malfunction (Open)

S5JB0A5104048

Wiring Diagram
Refer to “DTC P1874: 4L Switch Circuit Malfunction (Short)”.

DTC Detecting Condition and Trouble Area

DTC Confirmation Procedure

1) Connect scan tool to DLC with ignition switch OFF.
2) Clear DTCs in TCM and ECM memories by using scan tool.
3) Start engine and transfer position switch to “4L” position.
4) Keep engine running at idle speed for 10 seconds or more with select lever “D” range.
5) Start vehicle and increase vehicle speed to about 50 km/h (31 mile/h) in “4L” position for 2 minutes.
6) Stop vehicle.
7) Check DTC, pending DTC and freeze-frame data.

4

4L switch and its circuit check
1) Connect SUZUKI scan tool to DLC with ignition switch 

OFF.

2) Turn ignition switch ON.
3) Select “DATA LIST” mode on scan tool.
4) Check 4L/N switch signal (ON or OFF) on display when 

turning transfer position switch to each position.

4L/N switch specifications (scan tool)
“4H” position: OFF
“4L” position: ON

Is OFF / ON displayed as described above?

Intermittent trouble or 
faulty TCM. Check for 
intermittent trouble 
referring to “Intermittent 
and Poor Connection 
Inspection in Section 
00”. If OK, substitute a 
known-good TCM and 
recheck.

Go to Step 6.

5

4L/N switch and its circuit check
1) Turn ignition switch ON.
2) Check terminal voltage “E93-4” of TCM connector 

connected when turning transfer position switch to each 
position.

4L/N switch specifications
“4H” position: 10 – 14 V
“4L” position: 0 – 1 V

Is voltage as specified?

Intermittent trouble or 
faulty TCM. Check for 
intermittent trouble 
referring to “Intermittent 
and Poor Connection 
Inspection in Section 
00”. If OK, substitute a 
known-good TCM and 
recheck.

Go to Step 6.

6

4L/N switch check
1) Check 4WD low switch for operation referring to 

“Transfer Assembly Inspection: Motor-Shift Type 
(Transfer with Shift Actuator) in Section 3C”.

Is check result satisfactory?

4L/N circuit is shorted to 
ground. If wire and 
connections are OK, 
substitute a known-
good TCM and recheck.

Replace 4L/N switch.

Step

Action

Yes

No

DTC Detecting Condition

Trouble Area

Actual transfer position is 4L although TCM detected low switch is 
turned OFF with vehicle speed between 29 km/h (18 mile/h) and 
88 km/h (55 mile/h).
(1 driving cycle detection logic)

• 4L/N switch or its circuit.
• TCM