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.
2012 Mazda CX-9 FWD V6-3.7LFACTORY OEM SERVICE PROCEDURE
Body Control Module: Testing and Inspection
BODY CONTROL MODULE (BCM) INSPECTION
1. Remove the front scuff plate inner (LH). (See Front Scuff Plate Removal/Installation)
2. Remove the front side trim (LH). Front Side Trim Removal/Installation
3. Remove the dashboard under cover. (Driver side) Dashboard Under Cover Removal/Installation
4. Set the hood release lever out of the way. Service and Repair
5. Remove the BCM with the connector connected.
6. Measure the voltage at each terminal is as indicated in the Terminal Voltage Tables.
- If the voltage is not as specified in the Terminal Voltage Table, inspect the parts under "Inspection item (s)".
- If the system does not work properly even though the parts or related wiring harnesses do not have any malfunction, replace the BCM.
Terminal Voltage Table (Reference)
*1
With theft-deterrent system
*2
With seat warmer system
*3
With inverter
*4
With seat position memory function
*5
With sunroof system
*6
With car-navigation system
*7
With advanced keyless entry and start system
*8
With AWD
*9
With auto light system
Generated pulse (reference)
Pattern 1
- Terminal:
- Lock/unlock input (passenger-side door lock-link switch): 1E (+) -> body ground (-)
- Lock/unlock input (rear door lock-link switch (LH)): 6U (+) -> body ground (-)
- Lock/unlock input (rear door lock-link switch (RH): 6W (+) -> body ground (-)
- Oscilloscope setting: 1 V/DIV (Y), 1 ms/DIV (X), DC range
Pattern 2
- Terminal:
- Hood latch switch signal: 1B (+) -> body ground (-)
- Unlock input (Driver-side door lock-link switch): 5K (+) -> body ground (-)
- Lock input (Driver-side door lock-link switch): 5N (+) -> body ground (-)
- Oscilloscope setting: 1 V/DIV (Y), 1 ms/DIV (X), DC range
Pattern 3
- Terminal: 3V (+) -> body ground (-)
- Oscilloscope setting: 1 V/DIV (Y), 200 microsecond/DIV (X), DC range
Pattern 4
- Terminal:
- Courtesy light (RH) control: 2E (+) -> body ground (-)
- Courtesy light (LH) control: 4B (+) -> body ground (-)
- Interior light control: 7I (+) -> body ground (-)
- Oscilloscope setting: 5 V/DIV (Y), 5 ms/DIV (X), DC range
Pattern 5
- Terminal:
- Lock/unlock input (passenger-side door lock-link switch): 1E (+) -> body ground (-)
- Oscilloscope setting: 2 V/DIV (Y), 1 ms/DIV (X), DC range
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
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