CAN-BUS No. 4

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION:

When disconnecting the connector, verify that there is no looseness, damage, deformation, corrosion, or poor connection of the connector terminals.
When inspecting the connector, touch it with a paper clip or similar thin pin without directly inserting a tester probe into the terminal.
Disconnect the negative battery terminal before performing any work that requires handling of connectors.

CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW (US) - DIAGNOSTIC PROCEDURE (CAN-BUS No. 4)

Step	Inspection		Action
1	INSPECT FOR SHORT TO GROUND IN CAN-BUS No. 4 Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US)) Inspect for continuity at the following terminals: Between body control module (BCM) terminal 2D and body ground Between body control module (BCM) terminal 2B and body ground Is there continuity?	Yes	Short to ground in CAN-BUS No. 4 has occurred. Determine the location of a short to ground according to the diagnosis procedure for determining the location of a short to ground in CAN-BUS No. 4. (See DETERMINING SHORT TO GROUND LOCATION (CAN-BUS No. 4) (US))
1		No	Go to the next step.
2	INSPECT FOR SHORT TO POWER SUPPLY IN CAN-BUS No. 4 Connect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminal 2D and 2B. Is the voltage between 1.5-3.5 V?	Yes	Go to the next step.
2		No	Short to power supply in CAN-BUS No. 4 has occurred. Determine the location of a short to power supply according to the diagnosis procedure for determining the location of a short to power supply in CAN-BUS No. 4. (See DETERMINING SHORT TO POWER SUPPLY LOCATION (CAN-BUS No. 4) (US))
3	INSPECT FOR SHORT BETWEEN CIRCUITS IN CAN-BUS No. 4 Measure the voltage at body control module (BCM) terminals 2D and 2B. Is the voltage at body control module (BCM) terminals 2D and 2B the same?	Yes	Short between circuits in CAN-BUS No. 4 has occurred. Determine the location of a short between circuits according to the diagnosis procedure for determining the location of a short between circuits in CAN-BUS No. 4. (See DETERMINING SHORT BETWEEN CIRCUITS LOCATION (CAN-BUS No. 4) (US))
3		No	An open circuit in CAN-BUS No. 4 has occurred. Determine the location of an open circuit in CAN-BUS No. 4. (See DETERMINING OPEN CIRCUIT LOCATION (CAN-BUS No. 4) (US))