Diagnostic Procedure

WARNING: This page is about a different car, the 2025 Mazda CX-5. However, it is still accessible from the selected car via links, so may be relevant.

DTC B1A69:86 (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 .) Switch the ignition ON (engine off or on) and wait for 3s or more. Retrieve the front body control module (FBCM) DTCs using the M-MDS. (See DTC INSPECTION .) Is the same DTC displayed?	Yes	Go to the next step.
1		No	Go to Step 9.
2	INSPECT AUTO LIGHT SENSOR/HUMIDITY SENSOR/RAIN SENSOR CONNECTOR CONDITION Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Disconnect the auto light sensor/humidity sensor/rain 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.
2		No	Repair or replace the connector, then go to Step 8.
3	INSPECT FRONT BODY CONTROL MODULE (FBCM) CONNECTOR CONDITION 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 8.
4	INSPECT AUTO LIGHT SENSOR/HUMIDITY SENSOR/RAIN SENSOR CIRCUIT FOR SHORT TO GROUND Verify that the auto light sensor/humidity sensor/rain sensor and front body control module (FBCM) connectors are disconnected. Inspect for continuity between front body control module (FBCM) terminal 2G (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 auto light sensor/humidity sensor/rain sensor terminal C and front body control module (FBCM) terminal 2G. 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 8.
4		No	Go to the next step.
5	INSPECT AUTO LIGHT SENSOR/HUMIDITY SENSOR/RAIN SENSOR CIRCUIT FOR SHORT TO POWER SUPPLY Verify that the auto light sensor/humidity sensor/rain sensor and front body control module (FBCM) connectors are disconnected. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Switch the ignition ON (engine off or on). Measure the voltage at the front body control module (FBCM) terminal 2G (wiring harness-side). Is the voltage 0 V?	Yes	Go to the next step.
5		No	Refer to the wiring diagram and verify whether or not there is a common connector between auto light sensor/humidity sensor/rain sensor terminal C and front body control module (FBCM) terminal 2G. 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 Step 8.
6	INSPECT AUTO LIGHT SENSOR/HUMIDITY SENSOR/RAIN SENSOR CIRCUIT FOR SHORT TO OPEN CIRCUIT Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Verify that the auto light sensor/humidity sensor/rain sensor and front body control module (FBCM) connectors are disconnected. Inspect the wiring harness for continuity between auto light sensor/humidity sensor/rain sensor terminal C (wiring harness-side) and front body control module (FBCM) terminal 2G (wiring harness-side). Is there continuity?	Yes	Go to the next step.
6		No	Refer to the wiring diagram and verify whether or not there is a common connector between auto light sensor/humidity sensor/rain sensor terminal C and front body control module (FBCM) terminal 2G. 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 an open circuit. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has an open circuit. Go to Step 8.
7	VERIFY IF MALFUNCTIONING LOCATION IS AUTO LIGHT SENSOR/HUMIDITY SENSOR/RAIN SENSOR DEPENDING ON REPEATABILITY Always reconnect all disconnected connectors. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Clear the DTC for the front body control module (FBCM) using the M-MDS. (See CLEARING DTC .) Switch the ignition ON (engine off or on) and wait for 3s or more. Retrieve the front body control module (FBCM) DTCs using the M-MDS. (See DTC INSPECTION .) Is the same DTC displayed?	Yes	Go to the next step.
7		No	Replace the auto light sensor/humidity sensor/rain sensor, then go to the next step. (See RAIN SENSOR REMOVAL/INSTALLATION .)
8	VERIFY THAT REPAIRS HAVE BEEN COMPLETED Always reconnect all disconnected connectors. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Clear the DTC for the front body control module (FBCM) using the M-MDS. (See CLEARING DTC .) Switch the ignition ON (engine off or on) and wait for 3s or more. Retrieve the front body control module (FBCM) DTCs using the M-MDS. (See DTC INSPECTION .) 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.
8		No	Go to the next step.
9	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 .)
9		No	DTC troubleshooting completed.