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Front Body Control Module (FBCM) Inspection: Notes

  1. Remove the fuse box cover. (See RELAY AND FUSE BLOCK REMOVAL/INSTALLATION ).
  2. Remove the front body control module (FBCM) from the fuse box. (See FRONT BODY CONTROL MODULE (FBCM) REMOVAL/INSTALLATION ).
  3. Verify that the voltages of each of the terminals are as indicated in the Terminal Voltage Table (Reference).
    • If the voltage is not as indicated in the table, inspect the parts under Inspection item(s).
    • If the system does not launch normally even though inspection items are normal, specify the location of the malfunction based on the instructions from the on-board diagnostic system and the symptom troubleshooting, and perform repairs.

Terminal Voltage Table (Reference) 

G12265143Courtesy of MAZDA
Terminal Signal Connected to Measurement conditions Voltage (V) Inspection item(s)
1A Power supply HAZARD 25 A fuse Under any condition B+
  • HAZARD 25 A fuse
  • Related wiring harness
1B Power supply HAZARD 25 A fuse Under any condition B+
  • HAZARD 25 A fuse
  • Related wiring harness
1C Ignition power supply
  • Climate control unit
  • Rear seat warmer control unit
  • A/C relay
 Ignition switched ON (engine off) B+
  • Climate control unit
  • Rear seat warmer control unit
  • A/C relay
  • Related wiring harness
Ignition switched OFF (LOCK) 1.0 or less
1D Signal ground Body ground Under any condition 1.0 or less
  • Related wiring harness
1E Rear turn light (RH) control Rear turn light (RH) Ignition switched ON (engine off) Turn switch at right turn light position 1.0 or less ↔ B+
  • Rear turn light (RH)
  • Related wiring harness
Turn switch is in position other than above 1.0 or less
1F Side turn light (RH) control Side turn light (RH) Ignition switched ON (engine off) Turn switch at right turn light position 1.0 or less ↔ B+
  • Side turn light (RH)
  • Related wiring harness
Turn switch is in position other than above 1.0 or less
1G Front turn light (RH) control Front turn light (RH) Ignition switched ON (engine off) Turn switch at right turn light position 1.0 or less ↔ B+
  • Front turn light (RH)
  • Related wiring harness
Turn switch is in position other than above 1.0 or less
1H - - - - -
1I TNS relay control
  • TNS relay
  • Rear combination light (LH, RH)
  • License plate light (LH, RH)
 Light switch at TNS position B+
  • TNS relay
  • Rear combination light (LH, RH)
  • License plate light (LH, RH)
  • Related wiring harness
Light switch at OFF position 1.0 or less
1J - - - - -
1K - - - - -
1L Horn relay control Horn relay Horn switch not pressed B+
  • Horn relay
  • Related wiring harness
Horn switch pressed 1.0 or less
1M Headlight relay (LO) control Headlight LO relay No. 2 Ignition switched ON (engine off) Light switch at HEAD position 1.0 or less
  • Headlight LO relay No. 2
  • Related wiring harness
Light switch is in position other than above B+
1N - - - - -
1O (1) Theft-deterrent horn input signal Rear body control module (RBCM) M-MDS is connected and theft-deterrent is sounded using data monitor function 1.0 or less
  • Rear body control module (RBCM)
  • Related wiring harness
M-MDS is connected and theft-deterrent is not sounded using data monitor function B+
1P Rear window defogger relay control Rear window defogger relay Ignition switched ON (engine off) Rear window defogger switch OFF B+
  • Rear window defogger relay
  • Related wiring harness
Rear window defogger switch ON 1.0 or less
1Q - - - - -
1R (1) Theft-deterrent horn power supply R.WIPER 15 A fuse Under any condition B+
  • R.WIPER 15 A fuse
  • Related wiring harness
1S - - - - -
1T (1) Theft-deterrent horn output signal Theft-deterrent horn M-MDS is connected and theft-deterrent is sounded using data monitor function B+
  • Theft-deterrent horn
  • Related wiring harness
M-MDS is connected and theft-deterrent is not sounded using data monitor function 1.0 or less
2A Interior light power supply INTERIOR1 15A fuse Under any condition B+
  • INTERIOR1 15A fuse
  • Related wiring harness
2B Front turn light (LH) control Front turn light (LH) Ignition switched ON (engine off) Turn switch at left turn light position 1.0 or less ↔ B+
  • Front turn light (LH)
  • Related wiring harness
Turn switch is in position other than above 1.0 or less
2C Daytime running light control DRL relay Ignition switched ON (engine off) and light switch OFF Daytime running light illuminates B+
  • DRL relay
  • Related wiring harness
Daytime running light turns off 1.0 or less
2D Rear turn light (LH) control Rear turn light (LH) Ignition switched ON (engine off) Turn switch at left turn light position 1.0 or less ↔ B+
  • Rear turn light (LH)
  • Related wiring harness
Turn switch is in position other than above 1.0 or less
2F Side turn light (LH) control Side turn light (LH) Ignition switched ON (engine off) Turn switch at left turn light position 1.0 or less ↔ B+
  • Side turn light (LH)
  • Related wiring harness
Turn switch is in position other than above 1.0 or less
2G (2) LIN communication Humidity sensor/auto-light sensor/rain sensor Terminal used for communication therefore determination based on terminal voltage is not possible.
2H - - - - -
2I CAN_L CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
2J - - - - -
2K CAN_H CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
2L CAN_L CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
2M Ignition power supply C/U IG1 15 A fuse Ignition switched ON (engine off) B+
  • C/U IG1 15 A fuse
  • Related wiring harness
Ignition switched OFF (LOCK) 1.0 or less
2N CAN_L CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
2O - - - - -
2P CAN_H CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
2Q Brake fluid level switch signal Brake fluid level sensor Ignition switched ON (engine off) Brake fluid level is less than MIN (brake fluid level sensor ON) 1.0 or less
  • Brake fluid level sensor
  • Related wiring harness
Brake fluid level is MIN or more (brake fluid level sensor OFF) Wave pattern (See Pattern 1 ).
2R CAN_H CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
2S Washer level switch signal Washer fluid-level sensor Ignition switched ON (engine off) Washer level is less than MIN (washer fluid-level sensor ON) 1.0 or less
  • Washer fluid-level sensor
  • Related wiring harness
Washer level is MIN or more (washer fluid-level sensor OFF) Wave pattern (See Pattern 1 ).
2T (5) PTC heater signal PTC heater Terminal used for communication therefore determination based on terminal voltage is not possible.
2U Ignition power supply Start stop unit Ignition switched ON (engine off) B+
  • Start stop unit
  • Related wiring harness
Ignition switched OFF (LOCK) 1.0 or less
2V Headlight relay (LO) control Headlight LO relay No. 1 Ignition switched ON (engine off) Light switch at HEAD position 1.0 or less
  • Headlight LO relay No. 1
  • Related wiring harness
Light switch is in position other than above B+
2W Headlight (LO) switch signal Start stop unit Light switch at HEAD position 1.0 or less
  • Start stop unit
  • Related wiring harness
Light switch at OFF position B+
2X Headlight relay (HI) control Headlight HI relay Ignition switched ON (engine off) Headlight at HEAD position and dimmer switch at LO position B+
  • Headlight HI relay
  • Related wiring harness
Headlight at HEAD position and dimmer switch at HIGH or passing position 1.0 or less
2Y Windshield wiper(LO) switch signal Start stop unit Ignition switched ON (engine off) Windshield wiper switch at ON position 1.0 or less
  • Start stop unit
  • Related wiring harness
Windshield wiper switch at OFF position B+
2Z Blower motor relay control Blower relay Ignition switched ON (engine off) 1.0 or less
  • Blower relay
  • Related wiring harness
Ignition switched OFF (LOCK) B+
2AA Autostop switch signal Windshield wiper motor Ignition switched ON (engine off) Wipers are stopped in position other than park B+
  • Windshield wiper motor
  • Related wiring harness
Wipers are stopped in park position 1.0 or less
2AB (3) Front fog light relay control Front fog light relay Light switch at HEAD position Front fog light switch OFF B+
  • Front fog light relay
  • Related wiring harness
Front fog light switch ON 1.0 or less
3A Wiper power supply WIPER 20 A fuse Under any condition B+
  • WIPER 20 A fuse
  • Related wiring harness
3B Wiper power supply WIPER 20 A fuse Under any condition B+
  • WIPER 20 A fuse
  • Related wiring harness
3C Windshield wiper motor (HI) control Windshield wiper motor Ignition switched ON (engine off) Windshield wiper switch at HI position B+
  • Windshield wiper motor
  • Related wiring harness
Windshield wiper switch at OFF position 1.0 or less
3D Power ground Body ground Under any condition 1.0 or less
  • Related wiring harness
3E Windshield wiper motor (HI) control Windshield wiper motor Ignition switched ON (engine off) Windshield wiper switch at HI position B+
  • Windshield wiper motor
  • Related wiring harness
Windshield wiper switch at OFF position 1.0 or less
3F Windshield washer motor control Washer motor Ignition switched ON (engine off) Windshield washer switch ON B+
  • Washer motor
  • Related wiring harness
Windshield washer switch OFF 1.0 or less
3G Windshield wiper motor (LOW) control Windshield wiper motor Ignition switched ON (engine off) Windshield wiper switch at LOW position B+
  • Windshield wiper motor
  • Related wiring harness
Windshield wiper switch at OFF position 1.0 or less
3H Rear window washer motor control Washer motor Ignition switched ON (engine off) Rear washer switch ON B+
  • Washer motor
  • Related wiring harness
Rear washer switch OFF 1.0 or less
3I Windshield wiper motor (LOW) control Windshield wiper motor Ignition switched ON (engine off) Windshield wiper switch at LOW position B+
  • Windshield wiper motor
  • Related wiring harness
Windshield wiper switch at OFF position 1.0 or less
3J Interior illumination power supply
  • Electric parking brake switch
  • Shift panel
  • Drive selection switch
  • Steering switch
  • Commander switch
  • Hazard warning switch
  • Clock spring
  • Cluster switch
  • Front map light
  • Rear map light
 Light switch at TNS position B+
  • Electric parking brake switch
  • Shift panel
  • Drive selection switch
  • Steering switch Commander switch
  • Hazard warning switch
  • Clock spring
  • Cluster switch
  • Front map light
  • Rear map light
  • Related wiring harness
Light switch at OFF position -(4)
3K Power supply HAZARD 25 A fuse Under any condition B+
  • HAZARD 25 A fuse
  • Related wiring harness
3L Power supply HAZARD 25 A fuse Under any condition B+
  • HAZARD 25 A fuse
  • Related wiring harness
(1) With theft-deterrent system

(2) With auto wiper/auto light system

(3) With front fog light system

(4) The measured voltage changes according to the tester specification, therefore determination based on terminal voltage is not possible.

(5) Vehicles with PTC heater
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