Diagnostic Procedure

WARNING: This page is about a different car, the 2016 Mazda CX-5. However, it is still accessible from the selected car via links, so may be relevant.

STEP	Inspection		Action
1	VERIFY FRONT BODY CONTROL MODULE (FBCM) DTCs AGAIN Clear front body control module (FBCM) DTCs using the M-MDS. (See CLEARING DTC [FRONT BODY CONTROL MODULE (FBCM)] .) Switch the ignition ON (engine off or on) and wait for 5 s or more. Perform the front body control module (FBCM) DTC inspection using the M-MDS. (See DTC INSPECTION [FRONT BODY CONTROL MODULE (FBCM)] .) Is the DTC U0164:68 displayed?	Yes	A malfunction in LIN bus communication line can be considered. Repair or replace the wiring harness between the climate control unit and front body control module (FBCM), then go to the next step.
1		No	Go to Step 9.
2	INSPECT CLIMATE CONTROL UNIT CONNECTOR CONDITION Switch the ignition to off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Disconnect the climate control unit 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 CLIMATE CONTROL UNIT CIRCUIT FOR SHORT TO GROUND Verify that the climate control unit and front body control module (FBCM) connectors are disconnected. Inspect for continuity between front body control module (FBCM) terminal 1C (vehicle wiring harness side) and body ground. Is there continuity?	Yes	Repair or replace the wiring harness which is shorted to ground, then go to Step 8.
4		No	Go to the next step.
5	INSPECT CLIMATE CONTROL UNIT CIRCUIT FOR SHORT TO POWER SUPPLY Verify that the climate control unit and front body control module (FBCM) connectors are disconnected. Connect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Switch the ignition ON (engine off or on). Measure the voltage at front body control module (FBCM) terminal 1C (vehicle wiring harness side). Is the voltage 0 V ?	Yes	Go to the next step.
5		No	Repair or replace the wiring harness which is shorted to power supply, then go to Step 8.
6	INSPECT CLIMATE CONTROL UNIT CIRCUIT FOR OPEN CIRCUIT Verify that the climate control unit and front body control module (FBCM) connectors are disconnected. Switch the ignition to off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Inspect the wiring harness for continuity between climate control unit terminal N (vehicle wiring harness side) and front body control module (FBCM) terminal 1C (vehicle wiring harness side). Is there continuity?	Yes	Go to the next step.
6		No	Repair or replace the wiring harness which has an open circuit, then go to Step 8.
7	PERFORM DTC INSPECTION AND VERIFY IF MALFUNCTIONING PART IS CLIMATE CONTROL UNIT Reconnect all the disconnected connectors. Reconnect the disconnected negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Clear front body control module (FBCM) DTCs using the M-MDS. (See CLEARING DTC [FRONT BODY CONTROL MODULE (FBCM)] .) Switch the ignition ON (engine off or on) and wait for 5 s or more. Perform the front body control module (FBCM) DTC inspection using the M-MDS. (See DTC INSPECTION [FRONT BODY CONTROL MODULE (FBCM)] .) Is the DTC U0164:68 displayed?	Yes	Replace the climate control unit, then go to the next step. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER] .)
7		N	Go to Step 9.
8	VERIFY THAT REPAIRS HAVE BEEN COMPLETED Reconnect all the disconnected connectors. Reconnect the disconnected negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Clear front body control module (FBCM) DTCs using the M-MDS. (See CLEARING DTC [FRONT BODY CONTROL MODULE (FBCM)] .) Switch the ignition ON (engine off or on) and wait for 5 s or more. Perform the front body control module (FBCM) DTC inspection using the M-MDS. (See DTC INSPECTION [FRONT BODY CONTROL MODULE (FBCM)] .) Is the DTC U0164:68 displayed?	Yes	Replace the front body control module (FBCM), then go to the next step. (See FRONT BODY CONTROL MODULE (FBCM) REMOVAL/INSTALLATION .)
8		No	Go to the next step.
9	VERIFY IF OTHER DTCs DISPLAYED Are any other DTCs displayed?	Yes	Repair the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [FRONT BODY CONTROL MODULE (FBCM)] .)
9		No	DTC troubleshooting completed.