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. 7, 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 4 which has body control module (BCM) terminals 4R and 4Q. 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 4R and 4Q (wiring harness side). Is the voltage at body control module (BCM) terminals 4R and 4Q (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 CAN LINE BETWEEN CONNECTOR C-49 AND 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 C-49. Connect the connector 4 which has body control module (BCM) terminals 4R and 4Q. 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 4R and 4Q. Is the voltage at body control module (BCM) terminals 4R and 4Q the same?	Yes	Repair or replace the wiring harness between the body control module (BCM) and connector C-49 because the wiring harness is shorted between circuits.
2		No	Go to the next step.
3	INSPECT JB NO. 2 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Connect the connector C-49. Disconnect the connector C-48. 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 4R and 4Q. Is the voltage at body control module (BCM) terminals 4R and 4Q the same?	Yes	Replace the JB No. 2 because there is a short between circuits in the JB No. 2.
3		No	Go to the next step.
4	INSPECT BETWEEN AUDIO AMPLIFIER AND CONNECTOR C-48 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Inspect for continuity between audio amplifier terminals 2N and 2M. (With Bose® type audio). Inspect for continuity between audio amplifier terminals 1Q and 1S. (Without Bose® type audio) Is there continuity?	Yes	Go to the next step.
4		No	Go to Step 6.
5	INSPECT AUDIO AMPLIFIER FOR SHORT BETWEEN CIRCUITS Disconnect the audio amplifier connector. Inspect for continuity between audio amplifier terminals 2N and 2M (wiring harness side). (With Bose® type audio). Inspect for continuity between audio amplifier terminals 1Q and 1S (wiring harness side). (Without Bose® type audio) Is there continuity?	Yes	Repair or replace the wiring harness between the audio amplifier and connector C-48 because the wiring harness is shorted between circuits.
5		No	Replace the audio amplifier because there is a short between circuits in the audio amplifier. (See AUDIO AMPLIFIER REMOVAL/INSTALLATION (US) .)
6	INSPECT BETWEEN CONNECTOR C-48 AND CONNECTOR C-13 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Connect the connector C-48. Disconnect the connector C-13. 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 4R and 4Q. Is the voltage at body control module (BCM) terminals 4R and 4Q the same?	Yes	Repair or replace the wiring harness between the connector C-48 and connector C-13 because the wiring harness is shorted between circuits.
6		No	Go to the next step.
7	INSPECT CONNECTIVITY MASTER UNIT (CMU) FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connectivity master unit (CMU) connector. Connect the connector C-13. 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 4R and 4Q. Is the voltage at body control module (BCM) terminals 4R and 4Q the same?	Yes	Repair or replace the wiring harness between the connectivity master unit (CMU) and connector C-13 because the wiring harness is shorted between circuits.
7		No	Replace the connectivity master unit (CMU) because there is a short between circuits in the connectivity master unit (CMU). (See CONNECTIVITY MASTER UNIT (CMU) REMOVAL/INSTALLATION .)