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Home >> Mazda >> 2023 >> MX-5 Miata Club >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> On-Board Diagnostic - Start Stop Unit >> DTC B10C9-1F: Keyless Antenna (Interior, Front) Circuit Malfunction [Start Stop Unit] >> With Advanced Keyless Entry System >> Diagnostic Procedure
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Diagnostic Procedure

DTC B10C9:1F (START STOP UNIT) DIAGNOSTIC PROCEDURE - WITH ADVANCED KEYLESS ENTRY SYSTEM

Step Inspection Action
1 INSPECT KEYLESS ANTENNA (INTERIOR, FRONT) CONNECTOR CONDITION 
  • Switch the ignition off.
  • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
  • Disconnect the keyless antenna (interior, front) connector.
  • Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection.
  • Is the connector normal?
Yes Go to the next step.
No Repair or replace the connector, then go to Step 7.
2 INSPECT LF CONTROL UNIT CONNECTOR CONDITION 
  • Disconnect the LF control unit connector.
  • Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection.
  • Is the connector normal?
Yes Go to the next step.
No Repair or replace the connector, then go to Step 7.
3 INSPECT KEYLESS ANTENNA (INTERIOR, FRONT) CIRCUIT FOR SHORT TO GROUND 
  • Verify that the LF control unit and keyless antenna (interior, front) connectors are disconnected.
  • Inspect for continuity between the following terminals (wiring harness-side) and body ground:
    • Keyless antenna (interior, front) terminal B
    • Keyless antenna (interior, front) terminal A
  • Is there continuity?
Yes Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:
  • LF control unit terminal K-Keyless antenna (interior, front) terminal B
  • LF control unit terminal M-Keyless antenna (interior, front) terminal A

If there is a common connector: 
  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.
  • Repair or replace the malfunctioning part.

If there is no common connector: 
  • Repair or replace the wiring harness which has a short to ground.

Go to Step 7.
No Go to the next step.
4 INSPECT KEYLESS ANTENNA (INTERIOR, FRONT) CIRCUIT FOR OPEN CIRCUIT 
  • Verify that the LF control unit and keyless antenna (interior, front) connectors are disconnected.
  • Inspect for continuity between the following terminals (wiring harness-side):
    • LF control unit terminal K-Keyless antenna (interior, front) terminal B
    • LF control unit terminal M-Keyless antenna (interior, front) terminal A
  • Is there continuity?
Yes Go to the next step.
No Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:
  • LF control unit terminal K-Keyless antenna (interior, front) terminal B
  • LF control unit terminal M-Keyless antenna (interior, front) terminal A

If there is a common connector: 
  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit.
  • Repair or replace the malfunctioning part.

If there is no common connector: 
  • Repair or replace the wiring harness which has an open circuit.

Go to Step 7.
5 INSPECT LF CONTROL UNIT  Yes Go to the next step.
No Replace the LF control unit, then go to Step 7. (See LF CONTROL UNIT REMOVAL/INSTALLATION .)
6 VERIFY IF MALFUNCTIONING LOCATION IS KEYLESS ANTENNA (INTERIOR, FRONT) DEPENDING ON REPEATABILITY  Yes Replace the keyless antenna (interior, front), then go to the next step. (See KEYLESS ANTENNA REMOVAL/INSTALLATION .)
No Go to Step 8.
7 VERIFY THAT REPAIRS HAVE BEEN COMPLETED  Yes Repeat the inspection from Step 1.
No Go to the next step.
8 VERIFY IF OTHER DTCs DISPLAYED 
  • Are any other DTCs displayed?
Yes Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [START STOP UNIT] .)
No DTC troubleshooting completed.