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 MANUALSMAZDA20086 S SPORT, 4D HATCHBACK, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 605 (SYMPTOM TROUBLESHOOTING (KEYLESS ENTRY SYSTEM))NO. 2 ALL ON-BOARD DIAGNOSTIC FUNCTIONS INOPERATIVE

2008 Mazda 6 s Sport, 4D Hatchback, Standard

No. 2 All On-Board Diagnostic Functions Inoperative

2008 Mazda 6 s Sport, 4D Hatchback, StandardSECTION No. 2 All On-Board Diagnostic Functions Inoperative

WARNING: This page is about a different car, the 2007 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

When performing an asterisked (*) troubleshooting inspection, slightly shake the wiring harness and connectors while performing the inspection to discover whether poor contact points are, the cause of any intermittent malfunctions. If there is a problem, verify that the connectors, terminals and wiring harnesses are connected correctly and undamaged.

NO. 2 ALL ON-BOARD DIAGNOSTIC FUNCTIONS INOPERATIVE POSSIBLE CAUSE

2	All on-board diagnostic functions inoperative
DESCRIPTION	Malfunction in BCM power supply circuit, door latch switch circuit, BCM ground circuit, or keyless receiver.
POSSIBLE CAUSE	Malfunction in IG1 or power supply-signal circuit of BCM BCM power supply fuse malfunction Malfunction in wiring harness between BCM power supply fuses and BCM Malfunction in door open/closed signal circuit of BCM Door latch switch system malfunction BCM malfunction Malfunction in wiring harness between BCM and door latch switch Malfunction in BCM GND signal circuit Malfunction in wiring harness between BCM and ground Malfunction in keyless receiver Keyless receiver malfunction Malfunction in wiring harness between keyless receiver and BCM

NO. 2 ALL ON-BOARD DIAGNOSTIC FUNCTIONS INOPERATIVE DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	INSPECT BCM POWER SUPPLY FUSES Are the BCM power supply fuses normal?	Yes	Go to the next step.
1		No	Install an appropriate amperage fuse.
2	INSPECT DOOR LATCH SWITCH INSTALLATION Are the door latch switches installed securely?	Yes	Go to the next step.
2		No	Install the door latch switches securely, then go back to Step 5 of KEYLESS ENTRY SYSTEM PRELIMINARY INSPECTION.
*3	INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN FUSE BLOCK AND BCM) OR ELSEWHERE Turn the ignition switch to the ON position. Measure the voltage at the following BCM terminals: IG1 signal (terminal 40, 31, 7U) Power supply signal (terminal 3J, 3G, 3E, 4D,4P,8K) Is the voltage B+ ?	Yes	Go to the next step.
*3		No	Repair the wiring harness between the fuse block and BCM, then go to Step 13.
*4	INSPECT IF MALFUNCTION IS IN WIRING HARNESS (SHORT TO POWER SUPPLY BETWEEN FUSE BLOCK AND BCM, OR BETWEEN BCM AND GROUND) OR ELSEWHERE Turn the ignition switch to the LOCK position. Disconnect the BCM connector. Measure the voltage at the following BCM terminal (wiring harness-side): IG1 signal (terminal 40, 31, 7U) Is the voltage B+ ?	Yes	Repair the malfunctioning wiring harness, then go to Step 13.
*4		No	Go to the next step.
*5	INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN BCM AND GROUND) OR ELSEWHERE Is there continuity between BCM terminal 7A, 8A and ground?	Yes	Go to the next step.
*5		No	Repair the wiring harness between the BCM and ground, then go to Step 13.
6	INSPECT FOR CHECK CODE 04 IN INSTRUMENT CLUSTER Inspect the door latch switch using the instrument cluster input/output check mode. (See INSTRUMENT CLUSTER INPUT/OUTPUT CHECK MODE. ) Is DTC 04 displayed?	Yes	Go to the next step.
6		No	Repair the door latch switch system using the DTC 04 inspection procedure, then go to Step 13.
7	INSPECT BCM OR WIRING HARNESS (BETWEEN BCM AND DOOR LATCH SWITCHES FOR CONTINUITY) Open all doors. Is there continuity between BCM terminals 1F, 7B, 7D, 7F and ground?	Yes	Replace the BCM and reprogram the transmitter ID code, then go to the next step.
7		No	Repair the wiring harness between the BCM and door latch switches, then go to the next step.
8	INSPECT POWER SUPPLY FUSE Is the keyless receiver power supply fuse normal?	Yes	Go to the next step.
8		No	Install an appropriate amperage fuse.
9	INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN FUSE BLOCK AND KEYLESS RECEIVER) OR ELSEWHERE Turn the ignition switch to the ON position. Measure the voltage at the following keyless receiver terminal: IG1 signal (terminal A) Is the voltage B+ ?	Yes	Go to the next step.
9		No	Repair the wiring harness between the fuse block and keyless receiver, then go to Step 13.
10	INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN KEYLESS RECEIVER AND GROUND) OR ELSEWHERE Is there continuity between keyless receiver terminal E and ground?	Yes	Go to the next step.
10		No	Repair the wiring harness between the keyless receiver and ground, then go to Step 13.
11	INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN KEYLESS RECEIVER AND BCM) OR ELSEWHERE Turn the ignition switch to the ON position. Disconnect the keyless receiver connector and BCM connector. Is there continuity between the following terminals? 7I (BCM connector)-C (keyless receiver connector)	Yes	Go to the next step.
11		No	Repair the wiring harness between the keyless receiver and BCM, then go to Step 13.
12	INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN KEYLESS RECEIVER AND BCM) OR BCM Measure the voltage at keyless receiver terminal C. When transmitter operated: Any transmitter button is operated : 0.5 V Any transmitter button is not operated : 3.5 V Is the voltage normal?	Yes	Replace the BCM, then go to the next step.
12		No	Replace the keyless receiver, then go to the next step.
13	REINSPECT MALFUNCTION SYMPTOM AFTER REPAIR Does the keyless entry system operate properly?	Yes	Troubleshooting completed. Explain repairs to the customer.
13		No	Reinspect the malfunction symptoms, then repeat from Step 1 if the malfunction recurs.

RENDER: 1.0x

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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.