Diagnostic Procedure

WARNING: This page is about a different car, the 2014 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

DTC B1048:7B (FRONT BODY CONTROL MODULE) DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	VERIFY FRONT BODY CONTROL MODULE (FBCM) DTCs AGAIN Clear the DTC for the front body control module (FBCM) using the M-MDS. (See CLEARING DTC [FRONT BODY CONTROL MODULE (FBCM)] .) Retrieve the front body control module (FBCM) DTCs using the M-MDS. (See DTC INSPECTION [FRONT BODY CONTROL MODULE (FBCM)] .) 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. (See 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 Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5] .) 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 FRONT BODY CONTROL MODULE (FBCM) CONNECTOR Disconnect the front body control module (FBCM) 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 FOR SHORT TO GROUND IN BRAKE FLUID LEVEL SENSOR SIGNAL CIRCUIT Verify that the brake fluid level sensor and front body control module (FBCM) connectors are disconnected. Inspect for continuity between front body control module (FBCM) terminal 2Q (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 front body control module (FBCM) terminal 2Q. 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. (See 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. (See MASTER CYLINDER REMOVAL/INSTALLATION .)
7	VERIFY THAT REPAIRS HAVE BEEN COMPLETED Always reconnect all disconnected connectors. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5] .) Clear the DTC for the front body control module (FBCM) using the M-MDS. (See CLEARING DTC [FRONT BODY CONTROL MODULE (FBCM)] .) Retrieve the front body control module (FBCM) DTCs using the M-MDS. (See DTC INSPECTION [FRONT BODY CONTROL MODULE (FBCM)] .) Is the same DTC displayed?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the front body control module (FBCM). (See FRONT BODY CONTROL MODULE (FBCM) 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. (See DTC TABLE [FRONT BODY CONTROL MODULE (FBCM)] .)
8		No	DTC troubleshooting completed.