Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSMAZDA20066 I, 4D SEDAN, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTCOMMUNICATION DEVICESON-BOARD DIAGNOSTIC [BODY CONTROL SYSTEM)DTC B1320

2006 Mazda 6 i, 4D Sedan, Automatic

DTC B1320

2006 Mazda 6 i, 4D Sedan, AutomaticSECTION DTC B1320

DTC B1320 DETECTION CONDITION AND POSSIBLE CAUSE

DTC B1320	Door ajar (driver-side) circuit open
DETECTION CONDITION	Open circuit in wiring harness between BCM and front door switch (driver-side)
POSSIBLE CAUSE	Open circuit in wiring harness between BCM terminal 7B and door switch (driver-side) terminal A Door switch (driver-side) malfunction BCM malfunction

DTC B1320 DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	INSPECT DOOR SWITCH (DRIVER-SIDE) CONNECTOR Turn the ignition switch off. Disconnect the door switch (driver-side) connector. Inspect the door switch (driver-side) connector terminals for poor connection (such as damaged/pulled-out pins, and corrosion). Is there any malfunction?	Yes	Repair or replace the terminal, then go to Step 5.
1		No	Go to the next step.
2	INSPECT BCM CONNECTOR Disconnect the BCM connector. Inspect the BCM connector terminals for poor connection (such as damaged/pulled-out pins, and corrosion). Is there any malfunction?	Yes	Repair or replace the terminal, then go to Step 5.
2		No	Go to the next step.
3	INSPECT DOOR SWITCH (DRIVER-SIDE) SIGNAL CIRCUIT FOR OPEN CIRCUIT Inspect for continuity between BCM terminal 7B (wiring harness-side) and door switch (driver-side) terminal A (wiring harness-side). Is there continuity?	Yes	Go to the next step.
3		No	Repair or replace the wiring harness for a possible open circuit, then go to Step 5.
4	INSPECT FRONT DOOR LATCH AND LOCK ACTUATOR (DRIVER-SIDE) Inspect the front door latch and lock actuator (driver-side). (See DOOR SWITCH INSPECTION. ) Is there any malfunction?	Yes	Replace the door switch (driver-side), then go to the next step. (See DOOR SWITCH REMOVAL/INSTALLATION. )
4		No	Go to the next step.
5	VERIFY TROUBLESHOOTING COMPLETED Make sure to reconnect all disconnected connectors. Perform the self-test. (See BCM SELF-TEST ). Is the same DTC present?	Yes	Replace the BCM. (See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION. )
5		No	DTC troubleshooting completed.

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.