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. 4, 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 2 which has body control module (BCM) terminals 2D and 2B. 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 2D and 2B (wiring harness side). Is the voltage at body control module (BCM) terminals 2D and 2B (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-08 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-08. Connect the connector 2 which has body control module (BCM) terminals 2D and 2B. 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 2D and 2B. Is the voltage at body control module (BCM) terminals 2D and 2B the same?	Yes	Repair or replace the wiring harness between the body control module (BCM) and connector C-08 because the wiring harness is shorted between circuits.
2		No	Go to the next step.
3	INSPECT CAN LINE BETWEEN CONNECTOR C-69 AND CONNECTOR C-08 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector C-69. Connect the connector C-08. 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 2D and 2B. Is the voltage at body control module (BCM) terminals 2D and 2B the same?	Yes	Repair or replace the wiring harness between connector C-69 and connector C-08 because the wiring harness is shorted between circuits.
3		No	Go to the next step.
4	INSPECT CAN LINE BETWEEN ELECTRICAL SUPPLY UNIT (ESU) AND CONNECTOR C-69 FOR SHORT BETWEEN CIRCUITS Measure the voltage at electrical supply unit (ESU) terminals 1X and 1W. Is the voltage at electrical supply unit (ESU) terminals 1X and 1W the same?	Yes	Go to the next step.
4		No	Go to Step 6. (with parking sensor system) Go to Step 11. (without parking sensor system)
5	INSPECT ELECTRICAL SUPPLY UNIT (ESU) FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Connect the connector C-69. Disconnect the electrical supply unit (ESU) connector. 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 2D and 2B. Is the voltage at body control module (BCM) terminals 2D and 2B the same?	Yes	Repair or replace the wiring harness between the electrical supply unit (ESU) and connector C-69 because the wiring harness is shorted between circuits.
5		No	Replace the electrical supply unit (ESU) because there is a short between circuits in the electrical supply unit (ESU). (See ELECTRICAL SUPPLY UNIT (ESU) REMOVAL/INSTALLATION .)
6	INSPECT CAN LINE BETWEEN CONNECTOR C-58 AND CONNECTOR C-69 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Connect the connector C-69. Disconnect the connector C-58. 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 2D and 2B. Is the voltage at body control module (BCM) terminals 2D and 2B the same?	Yes	Repair or replace the wiring harness between connector C-58 and connector C-69 because the wiring harness is shorted between circuits.
6		No	Go to the next step.
7	INSPECT BETWEEN PARKING ASSIST UNIT (ULTRASONIC) AND CONNECTOR C-58 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Inspect for continuity between parking assist unit (ultrasonic) terminals 1X and 1Z. Is there continuity?	Yes	Go to the next step.
7		No	Go to Step 9.
8	INSPECT PARKING ASSIST UNIT (ULTRASONIC) FOR SHORT BETWEEN CIRCUITS Disconnect the parking assist unit (ultrasonic) connector. Inspect for continuity between parking assist unit (ultrasonic) terminals 1X and 1Z (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the parking assist unit (ultrasonic) and connector C-58 because the wiring harness is shorted between circuits.
8		No	Replace the parking assist unit (ultrasonic) because there is a short between circuits in the parking assist unit (ultrasonic). (See PARKING ASSIST UNIT (ULTRASONIC) REMOVAL/INSTALLATION .)
9	INSPECT BETWEEN REAR SIDE RADAR SENSOR (RH) AND CONNECTOR C-70 FOR SHORT BETWEEN CIRCUITS Connect the connector C-58. Disconnect the connector C-70. 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 2D and 2B. Is the voltage at body control module (BCM) terminals 2D and 2B the same?	Yes	Repair or replace the wiring harness between the connector C-70 and connector C-58 because the wiring harness is shorted between circuits.
9		No	Go to the next step.
10	INSPECT REAR SIDE RADAR SENSOR (RH) FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the rear side radar sensor (RH) connector. Inspect for continuity between rear side radar sensor (RH) terminals C and D (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the rear side radar sensor (RH) and connector C-70 because the wiring harness is shorted between circuits.
10		No	Replace the rear side radar sensor (RH) because there is a short between circuits in the rear side radar sensor (RH). (See REAR SIDE RADAR SENSOR REMOVAL/INSTALLATION .)
11	INSPECT CAN LINE BETWEEN CONNECTOR C-68 AND CONNECTOR C-69 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Connect the connector C-69. Disconnect the connector C-68. 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 2D and 2B. Is the voltage at body control module (BCM) terminals 2D and 2B the same?	Yes	Repair or replace the wiring harness between connector C-68 and connector C-69 because the wiring harness is shorted between circuits.
11		No	Go to the next step.
12	INSPECT CAN LINE BETWEEN CONNECTOR C-70 AND CONNECTOR C-68 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector C-70. Connect the connector C-68 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 2D and 2B. Is the voltage at body control module (BCM) terminals 2D and 2B the same?	Yes	Repair or replace the wiring harness between the connector C-70 and connector C-68 because the wiring harness is shorted between circuits.
12		No	Go to the next step.
13	INSPECT REAR SIDE RADAR SENSOR (RH) FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the rear side radar sensor (RH) connector. Inspect for continuity between rear side radar sensor (RH) terminals C and D (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the rear side radar sensor (RH) and connector C-70 because the wiring harness is shorted between circuits.
13		No	Replace the rear side radar sensor (RH) because there is a short between circuits in the rear side radar sensor (RH). (See REAR SIDE RADAR SENSOR REMOVAL/INSTALLATION .)