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 BETWEEN CIRCUITS LOCATION (CAN-BUS No. 8, US) - DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	INSPECT BODY CONTROL MODULE (BCM) FOR SHORT BETWEEN CIRCUITS 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 at body control module (BCM) terminals 3V and 3U (wiring harness side) the same?	Yes	Go to the next step.
1		No	Replace the body control module (BCM) because there is a short between circuits in the body control module (BCM). (See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION (US) .)
2	INSPECT TELEMATICS COMMUNICATION UNIT FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the telematics communication unit connector. Inspect for continuity between telematics communication unit terminals 1Q and 1S (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between telematics communication unit and body control module (BCM) because the wiring harness is shorted between circuits.
2		No	Replace the telematics communication unit because there is a short between circuits in the telematics communication unit. (See TELEMATICS COMMUNICATION UNIT REMOVAL/INSTALLATION .)