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 B10A8:12 (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 6.
2	INSPECT HEADLIGHT LO RELAY Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5] .) Remove the headlight LO relay. (See RELAY LOCATION .) Inspect the headlight LO relay. (See RELAY INSPECTION .) Is the headlight LO relay normal?	Yes	Go to the next step.
2		No	Replace the headlight LO relay, then go to Step 5. (See RELAY LOCATION .)
3	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.
3		No	Repair or replace the connector, then go to Step 5.
4	INSPECT FOR SHORT TO POWER SUPPLY IN HEADLIGHT LO RELAY CONTROL CIRCUIT Verify that the headlight LO relay is removed. Verify that the front body control module FBCM) connector is disconnected. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5] .) Switch the ignition ON (engine off or on). Measure the voltage at the front body control module (FBCM) terminal 1M (wiring harness-side). Is the voltage 0 V ?	Yes	Go to the next step.
4		No	Refer to the wiring diagram and verify whether or not there is a common connector between headlight LO relay terminal A and front body control module (FBCM) terminal 1M. 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 power supply. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has a short to power supply. Go to the next step.
5	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.
5		No	Go to the next step.
6	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)] .)
6		No	DTC troubleshooting completed.