Diagnostic Procedure

WARNING: This page is about a different car, the 2016 Mazda CX-3. However, it is still accessible from the selected car via links, so may be relevant.

Step	Inspection		Action
1	VERIFY BCM DTCs AGAIN Clear the DTC for the BCM using the M-MDS. (Refer to CLEARING DTC [BCM] .) Retrieve the BCM DTCs using the M-MDS. (Refer to DTC INSPECTION [BCM] .) Is the same DTC displayed?	Yes	Go to the next step.
1		No	Go to Step 8.
2	INSPECT BRAKE FLUID LEVEL Inspect the brake fluid level. (Refer to BRAKE FLUID INSPECTION .) Is the brake fluid level normal?	Yes	Go to the next step.
2		No	Add genuine brake fluid, then go to Step 7.
3	INSPECT BRAKE FLUID LEVEL SENSOR CONNECTOR CONDITION Switch the ignition off. Disconnect the negative battery cable. (Refer to NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .) Disconnect the brake fluid level sensor connector. Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. Is the connector normal?	Yes	Go to the next step.
3		No	Repair or replace the connector, then go to Step 7.
4	INSPECT BCM CONNECTOR CONDITION Disconnect the BCM connector. Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. Is the connector normal?	Yes	Go to the next step.
4		No	Repair or replace the connector, then go to Step 7.
5	INSPECT BRAKE FLUID LEVEL SENSOR SIGNAL CIRCUIT FOR SHORT TO GROUND Verify that the brake fluid level sensor and BCM connectors are disconnected. Inspect for continuity between BCM terminal 3R (wiring harness-side) and body ground. Is there continuity?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between brake fluid level sensor terminal B and BCM terminal 3R. If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has a short to ground. Go to Step 7.
5		No	Go to the next step.
6	INSPECT BRAKE FLUID LEVEL SENSOR Inspect the brake fluid level sensor. (Refer to BRAKE FLUID LEVEL SENSOR INSPECTION .) Is the brake fluid level sensor normal?	Yes	Go to the next step.
6		No	Replace the brake fluid level sensor, then go to the next step. (Refer to MASTER CYLINDER REMOVAL/INSTALLATION .)
7	VERIFY THAT REPAIRS HAVE BEEN COMPLETED Always reconnect all disconnected connectors. Connect the negative battery cable. (Refer to NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .) Clear the DTC for the BCM using the M-MDS. (Refer to CLEARING DTC [BCM] .) Retrieve the BCM DTCs using the M-MDS. (Refer to DTC INSPECTION [BCM] .) Is the same DTC displayed?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the BCM. (Refer to BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION .) Go to the next step.
7		No	Go to the next step.
8	VERIFY IF OTHER DTCs DISPLAYED Are any other DTCs displayed?	Yes	Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (Refer to DTC TABLE [BCM] .)
8		No	DTC troubleshooting completed.