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Diagnostic Procedure

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.
DTC C0023:14 (BCM) DIAGNOSTIC PROCEDURE

Step Inspection Results Action
1 VERIFY BODY CONTROL MODULE (BCM) DTCs AGAIN
  • Clear the DTC recorded in the memory. (See CLEARING DTC .)
  • Perform the DTC inspection for the body control module (BCM). (See DTC INSPECTION .)
  • Is the same Pending DTC present?
 Yes Go to the next step.
No Go to repair completion verification 2.
2 INSPECT REAR COMBINATION LIGHT (LH) CONNECTOR FOR MALFUNCTION
  • Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION .)
  • Are the connector and terminal normal?
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
3 INSPECT BRAKE LIGHT (LH) GROUND CIRCUIT FOR OPEN CIRCUIT
  • Inspect the applicable circuit for an open circuit. (See CIRCUIT INSPECTION .)
  • Is the circuit normal?
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
4 INSPECT REAR COMBINATION LIGHT (RH) CONNECTOR FOR MALFUNCTION
  • Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION .)
  • Are the connector and terminal normal?
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
5 INSPECT BRAKE LIGHT (RH) GROUND CIRCUIT FOR OPEN CIRCUIT
  • Inspect the applicable circuit for an open circuit. (See CIRCUIT INSPECTION .)
  • Is the circuit normal?
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
6 INSPECT HIGH-MOUNT BRAKE LIGHT CONNECTOR FOR MALFUNCTION
  • Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION .)
  • Are the connector and terminal normal?
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
7 INSPECT HIGH-MOUNT BRAKE LIGHT GROUND CIRCUIT FOR OPEN CIRCUIT
  • Inspect the applicable circuit for an open circuit. (See CIRCUIT INSPECTION .)
  • Is the circuit normal?
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
8 INSPECT ELECTRICAL SUPPLY UNIT (ESU) CONNECTOR FOR MALFUNCTION
  • Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION .)
  • Are the connector and terminal normal?
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
9 INSPECT BRAKE LIGHT SIGNAL CIRCUIT FOR OPEN CIRCUIT
  • Inspect the applicable circuit for an open circuit. (See CIRCUIT INSPECTION .)
  • Is the circuit normal?
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
10 INSPECT HIGH-MOUNT BRAKE LIGHT SIGNAL CIRCUIT FOR OPEN CIRCUIT
  • Inspect the applicable circuit for an open circuit. (See CIRCUIT INSPECTION .)
  • Is the circuit normal?
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
11 INSPECT BRAKE LIGHT FOR MALFUNCTION
  • Install/connect the part removed/disconnected during the troubleshooting procedure.
  • Depress the brake pedal.
  • Are there any lights among the following which are not turned on?
  • Brake light (LH)
    • Brake light (RH)
 Yes If the brake light (LH) malfunction does not turn on:

If the brake light (RH) malfunction does not turn on:
No Go to the next step.
12 INSPECT HIGH-MOUNT BRAKE LIGHT FOR MALFUNCTION
 Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification.
(See HIGH-MOUNT BRAKE LIGHT REMOVAL/INSTALLATION .)
13 INSPECT ELECTRICAL SUPPLY UNIT (ESU) FOR MALFUNCTION DEPENDING ON REPEATABILITY
  • Install/connect the part removed/disconnected during the troubleshooting procedure.
  • Clear the DTC recorded in the memory. (See CLEARING DTC .)
  • Perform the DTC inspection for the body control module (BCM). (See DTC INSPECTION .)
  • Is the same Pending DTC present?
 Yes Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error.
(See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW (US) .)
If the CAN communication is normal, replace the malfunctioning location and perform the repair completion verification.
(See ELECTRICAL SUPPLY UNIT (ESU) REMOVAL/INSTALLATION .)
No Go to the next step.
Repair completion verification 1 VERIFY THAT VEHICLE IS REPAIRED
  • Install/connect the part removed/disconnected during the troubleshooting procedure.
  • Clear the DTC recorded in the memory. (See CLEARING DTC .)
  • Perform the DTC inspection for the body control module (BCM). (See DTC INSPECTION .)
  • Is the same Pending DTC present?
 Yes Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error.
(See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW (US) .)
If the CAN communication is normal, perform the diagnosis from Step 1.
No Go to the next step.
Repair completion verification 2 VERIFY IF OTHER DTC IS DISPLAYED
  • Perform the DTC inspection. (See DTC INSPECTION .)
  • Are any other DTCs displayed?
 Yes Repair the malfunctioning location according to the applicable DTC troubleshooting.
No DTC troubleshooting completed.
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