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 B13BD:87 [DASH-ELECTRICAL SUPPLY UNIT] DIAGNOSTIC PROCEDURE

Step	Inspection	Results	Action
1	INSPECT CLOCK SPRING CONNECTOR FOR MALFUNCTION Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION .) Are the connector and terminal normal?	Yes	Go to the next step.
1		No	Repair or replace the malfunctioning location and perform the repair completion verification.
2	INSPECT HEATED STEERING WHEEL CONTROL UNIT CONNECTOR FOR MALFUNCTION Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION .) Are the connector and terminal normal?	Yes	Go to the next step.
2		No	Repair or replace the malfunctioning location and perform the repair completion verification.
3	INSPECT CLOCK SPRING FOR MALFUNCTION Inspect the applicable part. (See CLOCK SPRING INSPECTION [TWO-STEP DEPLOYMENT CONTROL SYSTEM - US/CANADA SPEC.] .) Is the part normal?	Yes	Go to the next step.
3		No	Repair or replace the malfunctioning location and perform the repair completion verification. (See CLOCK SPRING REMOVAL/INSTALLATION [TWO-STEP DEPLOYMENT CONTROL SYSTEM - US/CANADA SPEC.] .)
4	INSPECT DASH-ELECTRICAL SUPPLY UNIT CONNECTOR FOR MALFUNCTION Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION .) Are the connector and terminal normal?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification.
4		No	Go to the next step.
5	INSPECT HEATED STEERING WHEEL CONTROL UNIT LIN COMMUNICATION LINE 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.
5		No	Repair or replace the malfunctioning location and perform the repair completion verification.
6	INSPECT HEATED STEERING WHEEL CONTROL UNIT LIN COMMUNICATION LINE FOR SHORT TO POWER SUPPLY Inspect the applicable circuit for a short to power supply. (See CIRCUIT INSPECTION .) Is the circuit normal?	Yes	Go to the next step.
6		No	Repair or replace the malfunctioning location and perform the repair completion verification.
7	INSPECT HEATED STEERING WHEEL CONTROL UNIT LIN COMMUNICATION LINE FOR OPEN CIRCUIT Inspect the applicable circuit for an open circuit. (See CIRCUIT INSPECTION .) Is the circuit normal?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning location and perform the repair completion verification.
8	INSPECT HEATED STEERING WHEEL CONTROL UNIT 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 dash-electrical supply unit. (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 HEATED STEERING WHEEL CONTROL UNIT REMOVAL/INSTALLATION .)
8		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 dash-electrical supply unit. (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 dash-electrical supply unit, then go to the next step. (See DASH-ELECTRICAL SUPPLY UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER (US)] .) (See DASH-ELECTRICAL SUPPLY UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER (US)] .)
Repair completion verification 1		No	Go to the next step.
Repair completion verification 2	VERIFY IF OTHER DTCs DISPLAYED Perform the DTC inspection. (See DTC INSPECTION .) Are any DTCs displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting.
Repair completion verification 2		No	DTC troubleshooting completed.