Determination Procedure

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 cable before performing any work that requires handling of connectors.

DETERMINING SHORT TO POWER SUPPLY LOCATION (CAN-BUS No. 8, US) - DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	INSPECT CAN LINE BETWEEN BODY CONTROL MODULE (BCM) AND TELEMATICS COMMUNICATION UNIT FOR SHORT TO POWER SUPPLY Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector 3 which has body control module (BCM) terminals 3V and 3U. 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) terminals 3V and 3U (wiring harness side). Is the voltage between 1.5-3.5 V?	Yes	Replace the body control module (BCM) because there is a short to the power supply in the body control module (BCM). (See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION (US) .)
1		No	Go to the next step.
2	INSPECT TELEMATICS COMMUNICATION UNIT FOR SHORT TO POWER SUPPLY Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the telematics communication unit connector. Connect the connector 3 which has body control module (BCM) terminals 3V and 3U. 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) terminals 3V and 3U. Is the voltage between 1.5-3.5 V?	Yes	Replace the telematics communication unit because there is a short to the power supply in the telematics communication unit. (See TELEMATICS COMMUNICATION UNIT REMOVAL/INSTALLATION .)
2		No	Repair or replace the wiring harness between the telematics communication unit and body control module (BCM) because the wiring harness is shorted to the power supply.