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 B1038:63 [DASH-ELECTRICAL SUPPLY UNIT (US)] DIAGNOSTIC PROCEDURE

Step	Inspection	Results	Action
1	VERIFY OTHER DTCs RELATED TO SEAT WARMER UNIT (LH) CIRCUIT Perform the DTC inspection for the dash-electrical supply unit. (See DTC INSPECTION .) Are other DTCs related to the seat warmer unit (LH) circuit displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [DASH-ELECTRICAL SUPPLY UNIT (US)] .)
1		No	Go to the next step.
2	INSPECT SEAT WARMER 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 SEAT WARMER UNIT (LH) AND SEAT WARMER UNIT (LH) SIGNAL CIRCUIT AND GROUND CIRCUIT FOR MALFUNCTION Install/connect the part removed/disconnected during the troubleshooting procedure. Switch the ignition off. Switch the ignition ON (engine off or on). With the seat warmer switch (LH) turned on, measure the resistance between the following terminals (vehicle wiring harness side). Seat warmer control unit terminal 2O Seat warmer control unit terminal 2X Does the resistance change with the elapse of time (temperature increase)?	Yes	Go to the next step.
3		No	Repair or replace the malfunctioning location and perform the repair completion verification. (See FRONT SEAT REMOVAL/INSTALLATION (US) .)
4	INSPECT SEAT WARMER 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 POSITION MEMORY CONTROL MODULE REMOVAL/INSTALLATION (US) .)
4		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.