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 B1A21:2B (CONNECTIVITY MASTER UNIT) DIAGNOSTIC PROCEDURE (4SD)

Step	Inspection	Results	Action
1	INSPECT BODY CONTROL MODULE (BCM), CONNECTIVITY MASTER UNIT (CMU), AND REMOTE TUNER (RT) FOR MALFUNCTION Perform the DTC inspection for the body control module (BCM) and the connectivity master unit (CMU). (Refer to the [DTC INSPECTION] in the appropriate service information)) Are any of the following DTCs displayed? DTC related to malfunction in BCM DTC related to malfunction in CMU B1A33:49 for CMU	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting. (Refer to the [DTC TABLE [BODY CONTROL MODULE (BCM)]] in the appropriate service information) (See DTC TABLE [CONNECTIVITY MASTER UNIT (US)] .)
1		No	Go to the next step.
2	INSPECT REMOTE TUNER (RT) CONNECTOR FOR MALFUNCTION Inspect the applicable connector and terminal. (Refer to the [CONNECTOR INSPECTION] in the appropriate service information) 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 FM ANTENNA AMPLIFIER SIGNAL CIRCUIT FOR SHORT TO GROUND Inspect the applicable circuit for a short to ground. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Go to the next step.
3		No	Repair or replace the malfunctioning location and perform the repair completion verification. (Refer to the [ANTENNA FEEDER NO. 1 REMOVAL/INSTALLATION] in the appropriate service information)
4	INSPECT FM ANTENNA AMPLIFIER SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY Inspect the applicable circuit for a short to power supply. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning location and perform the repair completion verification. (Refer to the [ANTENNA FEEDER NO. 1 REMOVAL/INSTALLATION] in the appropriate service information)
5	INSPECT FM ANTENNA AMPLIFIER SIGNAL CIRCUIT AND MUTUAL SHIELD FOR SHORT CIRCUIT Inspect the applicable circuits for a short circuit. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Replace the FM antenna amplifier and perform the repair completion verification. (Refer to the [ANTENNA AMPLIFIER REMOVAL/INSTALLATION] in the appropriate service information)
5		No	Repair or replace the malfunctioning location and perform the repair completion verification. (Refer to the [ANTENNA FEEDER NO. 1 REMOVAL/INSTALLATION] in the appropriate service information)
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. (Refer to the [CLEARING DTC] in the appropriate service information) Perform the DTC inspection for the connectivity master unit (CMU). (Refer to the [DTC INSPECTION] in the appropriate service information) Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (Refer to the [CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW] in the appropriate service information) If the CAN communication is normal, perform the diagnosis from Step 1. If the malfunction recurs, replace the remote tuner (RT), then go to the next step. (Refer to the [REMOTE TUNER (RT) REMOVAL/INSTALLATION] in the appropriate service information)
Repair completion verification 1		No	Go to the next step.
Repair completion verification 2	VERIFY IF OTHER DTCs ARE DISPLAYED Perform the DTC inspection. (Refer to the [DTC INSPECTION] in the appropriate service information) Is a DTC displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting.
Repair completion verification 2		No	DTC troubleshooting completed.