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Home >> Mazda >> 2023 >> 3 Select, 4D Hatchback >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> On-Board Diagnostic - Body Control Module (BCM) (3 Of 4) >> DTC U0300-57: Body Control Module (BCM) Internal Malfunction [Body Control Module (BCM)] >> Diagnostic Procedure
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Diagnostic Procedure

DTC U0300:57 - BODY CONTROL MODULE (BCM) DIAGNOSTIC PROCEDURE

Step Inspection Results Action
1 VERIFY BODY CONTROL MODULE (BCM) REPLACEMENT RECORD 
  • Verify if the body control module (BCM) has been replaced before performing this troubleshooting procedure.
  • Has the body control module (BCM) been replaced?
Yes After performing the procedure required for the body control module (BCM) replacement again, perform the repair completion verification according to the [BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION].
(See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION .)
No Go to the next step.
2 INSPECT BODY CONTROL MODULE (BCM) FOR MALFUNCTION 
  • 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 body control module (BCM) and perform the repair completion verification.
(See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION .)
No Go to the next step.
Repair completion verification 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.