Suzuki Grand Vitara JB416 / JB420 (ESP model). Service manual - part 108

10C-17 Immobilizer Control System: 

DTC P1638: Immobilizer Information Mismatched

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Wiring Diagram
Refer to “Immobilizer Control System Wiring Circuit Diagram”

DTC Detecting Condition and Trouble Area

Troubleshooting

Detecting Condition

Trouble Area

• The immobilizer control system information in ECM and 

the one in BCM does not match.

• The registration of the immobilizer control system 

information in ECM is failed.

• Use of the wrong ECM
• Steering angle sensor (if equipped) faulty
• Keyless start control module (if equipped) faulty
• 4WD control module (if equipped)
• TCM (if equipped) faulty
• CAN communication wire circuits faulty
• BCM faulty
• Combination meter faulty
• ABS/ESP

® control module faulty

• ECM faulty

Step

Action

Yes

No

1

Diagnostic Trouble Code (DTC) confirmation
1) Clear DTC(s) referring to “Diagnostic Trouble Code 

(DTC) Clearance in related manual”.

2) Turn the ignition switch to OFF position.
3) Check if any DTC is detected referring to “Diagnostic 

Trouble Code (DTC) Check in related manual”.

Is DTC P1638 still detected?

Go to Step 2.

The troubleshooting is 
completed.

2

Diagnostic Trouble Code (DTC) confirmation
1) Disconnect negative (–) cable from battery for more than 

5 seconds.

2) Connect negative (–) cable to battery.
3) Check if any DTC is detected referring to “Diagnostic 

Trouble Code (DTC) Check in related manual”.

Is DTC P1638 still detected?

Go to Step 3.

The troubleshooting is 
completed.

3

Check ECM specification
1) Check ECM part number to see if ECM is applicable to 

the vehicle in service.

Is a correct ECM used for the vehicle in service?

Go to Step 2.

Replace ECM with the 
correct one and recheck 
if DTC P1638 is still 
detected by ECM.

4

Diagnostic Trouble Code (DTC) check in ECM

Is any DTC other than P1638 detected in Step 1?

Perform the 
troubleshooting 
referring to the 
corresponding 
flowchart.

Go to Step 3.

5

Diagnostic Trouble Code (DTC) check in BCM
1) Check BCM for DTC referring to “DTC Check in Section 

10B in related manual”.

Is any DTC detected?

Perform the 
troubleshooting 
referring to the 
corresponding flowchart 
in Section 10B.

Go to Step 5.

Immobilizer Control System:  10C-18

6

Replacement of BCM
1) Replace BCM with new one referring to “BCM Removal 

and Installation in Section 10B in related manual”.

2) Check ECM for DTC referring to “Diagnostic Trouble 

Code (DTC) Check in related manual”.

Is DTC P1638 still detected?

Go to Step 6.

The troubleshooting is 
completed.

7

Replacement of ECM
1) Replace ECM with new one referring to “Engine Control 

Module (ECM) Removal and Installation in Section 1C in 
related manual”.

2) Check ECM for DTC referring to “Diagnostic Trouble 

Code (DTC) Check in related manual”.

Is DTC P1638 still detected?

Recheck CAN 
communication wire 
circuits and poor 
connection at ECM, 
ABS/ESP

® control 

module and BCM 
connectors.

The troubleshooting is 
completed.

Step

Action

Yes

No

10E-1 Keyless Start System: 

Control Systems

Keyless Start System

Precautions

Precautions in Diagnosing Troubles

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• The keyless start system executes data transmission/reception by means of the radio wave. Therefore, proper 

operation may not be obtained if use of the door lock function and engine start function of the keyless start system 
is attempted near the place where strong radio wave is emitted (TV and radio broadcasting stations, etc.).

• Diagnostic information stored in keyless start control module memory can be checked only by key indicator lamp.
• Be sure to use the trouble diagnosis procedure as described in “Keyless Start System Check in related manual”. 

Failure to follow it may result in incorrect diagnosis. (Some other DTC may be stored by mistake in the memory of 
keyless start control module during inspection.)

• Be sure to read “Precautions for Electrical Circuit Service in Section 00 in related manual” before inspection and 

observe what is written there.

• Communication of ECM, BCM, TCM (A/T model), 4WD control module (if equipped), ABS or ESP

® control module, 

keyless start control module, steering angle sensor (if equipped) and combination meter is established by CAN 
(Controller Area Network). (For detail of CAN communication for keyless start control module, refer to “CAN 
Communication System Description”). Therefore, handle CAN communication line with care referring to “Precaution 
for CAN Communication System in Section 00 in related manual”.

• Replacement of the keyless start control module

When keyless start control module is replaced with new one, make sure that register remote controller ID code to 
Keyless start control module correctly according to “Registration Procedure for Remote Controller ID Code in 
related manual”.

• Keyless start control module substitution

When the keyless start control module used in another vehicle was installed in the vehicle, register the ID code of 
the remote controller in the keyless start control module as well as the ignition key transponder code for the 
immobilizer control system in ECM. For the registration procedure of the ignition key transponder code, refer to 
“Registration of the Ignition Key in Section 10C in related manual”.

Keyless Start System:  10E-2

General Description

Operation Area of Remote Controller

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Shown below are the operation areas of the remote controller for the keyless engine start function and door lock 
function of the keyless start system.

[A]

[C]

[B]

1

2

5

6

3

3

4

1

2

2

1

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[A]: Door lock function of keyless start system

3. Center antenna

[B]: Function of keyless start system to prevent remote controller from being closed in 

vehicle compartment

4. Luggage room antenna

[C]: Keyless engine start function

5. Vehicle compartment including luggage room

1. About 80 cm (31.5 in, 2.6 ft)

6. Vehicle compartment excluding luggage room

2. Each door antenna