April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis Procedure

Regarding Wiring Diagram information, refer to VEHICLE SECURITY SYSTEM: WIRING DIAGRAM [KING CAB] or VEHICLE SECURITY SYSTEM: WIRING DIAGRAM [CREW CAB] .

DIAGNOSIS PROCEDURE

Step	Action	YES	NO
1	CHECK DOOR KEY CYLINDER SWITCH LH With SDT Check front door lock assembly LH (key cylinder switch) ("KEY CYL LK-SW") and ("KEY CYL UN-SW") in "Data list" mode in SDT. Refer to [SDT FUNCTION (BCM - DOOR LOCK) ] When key inserted in front key cylinder is turned to LOCK: KEY CYL LK-SW: ON When key inserted in front key cylinder is turned to UNLOCK: KEY CYL UN-SW: ON Without SDT Check voltage between BCM connector M18 terminals 7, 8 and ground. Is the inspection result normal?	Front door lock assembly LH (key cylinder switch) signal is OK.	GO TO 2.
2	CHECK FRONT DOOR LOCK ASSEMBLY LH (KEY CYLINDER SWITCH) Turn ignition switch OFF. Disconnect front door lock assembly LH (key cylinder switch). Check continuity between front door lock assembly LH (key cylinder switch) connector terminals 3, 4 and 5. Courtesy of SUZUKI OF AMERICA CORP. Is the inspection result normal?	GO TO 3.	Replace front door lock assembly LH (key cylinder switch). Refer to [FRONT DOOR LOCK: REMOVAL AND INSTALLATION ]
3	CHECK FRONT DOOR LOCK ASSEMBLY LH HARNESS Disconnect BCM. Check continuity between BCM connector M18 terminals 7, 8 and front door lock assembly LH connector D14 terminals 3, 5. Courtesy of SUZUKI OF AMERICA CORP. 7 - 3: Continuity should exist. 8 - 5: Continuity should exist. 3. Check continuity between BCM connector M18 terminals 7, 8 and ground. 7 - Ground: Continuity should not exist. 8 - Ground: Continuity should not exist. Is the inspection result normal?	GO TO 4.	Repair or replace harness.
4	CHECK FRONT DOOR LOCK ASSEMBLY LH GROUND Check continuity between front door lock assembly LH connector D14 terminal 4 and ground. 4 - Ground: Continuity should exist. Is the inspection result normal?	GO TO 5.	Repair or replace harness.
5	CHECK BCM OUTPUT VOLTAGE Connect BCM. Check voltage between BCM connector M18 terminals 7, 8 and ground. Courtesy of SUZUKI OF AMERICA CORP. 7 - Ground: Approx. 5V 8 - Ground: Approx. 5V Is the inspection result normal?	Check condition of the harness and connector.	Replace BCM. Refer to [BCM (BODY CONTROL MODULE): REMOVAL AND INSTALLATION ]