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Home >> Mazda >> 2021 >> CX-30 Turbo Premium >> Repair and Diagnosis >> External Pages >> Different car >> Section 101 (On-Board Diagnostic - Body Control Module (BCM) (2 Of 3)) >> DTC B1A79-14: Rear Fog Light Circuit Malfunction (BCM) >> Diagnostic Procedure >> Overview

Diagnostic Procedure: Overview

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 B1A79:14 (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 LIFTGATE 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.
3 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.
4 INSPECT REAR FOG LIGHT SIGNAL CIRCUIT FOR SHORT TO GROUND
  • Inspect the applicable circuit for a short to ground. (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.
5 INSPECT REAR FOG LIGHT FOR MALFUNCTION
  • Install/connect the part removed/disconnected during the troubleshooting procedure.
  • Operate the fog light switch to the R.FOG position.
  • Does the rear fog light turn on?
 Yes Repair or replace the malfunctioning location and perform the repair completion verification.
(See LIFTGATE LIGHT REMOVAL/INSTALLATION .)
No Go to the next step.
6 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 repair completion verification 2.
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.
  • If the malfunction recurs, replace the body control module (BCM), then go to the next step.
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.


DTC B1A79:14 (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 FOG 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.
3 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.
4 INSPECT REAR FOG LIGHT SIGNAL CIRCUIT FOR SHORT TO GROUND
  • Inspect the applicable circuit for a short to ground. (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.
5 INSPECT REAR FOG LIGHT FOR MALFUNCTION
  • Install/connect the part removed/disconnected during the troubleshooting procedure.
  • Operate the fog light switch to the R.FOG position.
  • Does the rear fog light turn on?
 Yes Repair or replace the malfunctioning location and perform the repair completion verification.
No Go to the next step.
6 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 repair completion verification 2.
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.
  • If the malfunction recurs, replace the body control module (BCM), then go to the next step.
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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