FixVault

Brake Light Unit Inspection

  1. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
  2. Remove the following parts:
  3. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
  4. Verify that the voltages of each of the terminals are as indicated in the terminal voltage table.
    • If the voltage is not as indicated in the table, inspect the parts under Inspection item (s).
      • If the system does not work normally even though the parts or related wiring harnesses do not have any malfunction, replace the brake light unit. (See BRAKE LIGHT UNIT REMOVAL/INSTALLATION .)
      Fig 1: Identifying Brake Light Unit Connector Terminals
      G10988026Courtesy of MAZDA MOTORS CORP.
Terminal Signal Connection Test condition Voltage (V) Inspection item(s)
A Ground Body ground Under any condition 1.0 or less Body ground
D Brake light illumination request signal Rear body control module (RBCM) Because this terminal is for communication, good/no good judgment by terminal voltage is not possible.
F Power supply STOP 10 A fuse Under any condition B+
  • STOP 10 A fuse
  • Battery
G High-mount brake light signal High-mount brake light Brake pedal depressed B+ High-mount brake light
Brake pedal not depressed 1.0 or less
H Brake light illumination status signal DSC HU/CM Brake pedal depressed B+ DSC HU/CM
Brake pedal not depressed 1.0 or less
I Brake switch (No. 1 signal) signal Brake switch (No. 1 signal) Brake pedal depressed B+ Brake switch (No. 1 signal)
Brake pedal not depressed 1.0 or less
J Brake light signal
  • Brake light
  • Rear body control module (RBCM)
Brake pedal depressed B+
  • Brake light
  • Rear body control module (RBCM)
Brake pedal not depressed 1.0 or less