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 terminal before performing any work that requires handling of connectors.

DETERMINING SHORT BETWEEN CIRCUITS LOCATION (CAN-BUS No. 1, US) - DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	INSPECT BODY CONTROL MODULE (BCM) FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector 3 which has body control module (BCM) terminals 3X and 3W. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W (wiring harness side). Is the voltage at body control module (BCM) terminals 3X and 3W (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-40 AND BODY CONTROL MODULE (BCM) FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector C-40. Connect the connector 3 which has body control module (BCM) terminals 3X and 3W. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between the body control module (BCM) and connector C-40 because the wiring harness is shorted between circuits.
2		No	Go to the next step.
3	INSPECT CAN LINE BETWEEN EPS CONTROL MODULE AND CONNECTOR C-40 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Inspect for continuity between EPS control module terminals 2C and 2A. Is there continuity?	Yes	Go to the next step.
3		No	Go to Step 5.
4	INSPECT EPS CONTROL MODULE FOR SHORT BETWEEN CIRCUITS Disconnect the EPS control module connector. Inspect for continuity between EPS control module terminals 2C and 2A (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the EPS control module and connector C-40 because the wiring harness is shorted between circuits.
4		No	Replace the EPS control module because there is a short between circuits in the EPS control module. (See STEERING WHEEL AND COLUMN REMOVAL/INSTALLATION (US) .)
5	INSPECT CAN LINE BETWEEN ADAPTIVE FRONT LIGHTING SYSTEM (AFS) CONTROL MODULE AND CONNECTOR C-40 FOR SHORT BETWEEN CIRCUITS Inspect for continuity between adaptive front lighting system (AFS) control module terminals E and H. Is there continuity?	Yes	Go to the next step.
5		No	Go to Step 7.
6	INSPECT ADAPTIVE FRONT LIGHTING SYSTEM (AFS) CONTROL MODULE FOR SHORT BETWEEN CIRCUITS Disconnect the adaptive front lighting system (AFS) control module connector. Inspect for continuity between adaptive front lighting system (AFS) control module terminals E and H (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the adaptive front lighting system (AFS) control module and connector C-40 because the wiring harness is shorted between circuits.
6		No	Replace the adaptive front lighting system (AFS) control module because there is a short between circuits in the adaptive front lighting system (AFS) control module. (See ADAPTIVE FRONT LIGHTING SYSTEM (AFS) CONTROL MODULE REMOVAL/INSTALLATION (US) .)
7	INSPECT CAN LINE BETWEEN CONNECTOR C-13 AND CONNECTOR C-40 FOR SHORT BETWEEN CIRCUITS Disconnect the connector C-13. Connect the connector C-40. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between connector C-13 and connector C-40 because the wiring harness is shorted between circuits.
7		No	Go to the next step.
8	INSPECT CAN LINE BETWEEN CONNECTOR C-21 AND CONNECTOR C-13 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector C-21. Connect the connector C-13. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between connector C-21 and connector C-13 because the wiring harness is shorted between circuits.
8		No	Go to the next step.
9	INSPECT CAN LINE BETWEEN CONNECTOR C-21 AND PCM FOR SHORT BETWEEN CIRCUITS Measure the voltage at PCM terminals 2S and 2T. Is the voltage at PCM terminals 2S and 2T the same?	Yes	Go to Step 13.
9		No	Go to the next step.
10	INSPECT CAN LINE BETWEEN CONNECTOR C-21 AND CONNECTORS C-55, C-56 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connectors C-55, C-56. Connect the connector C-21. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between connector C-21 and connectors C-55, C-56 because the wiring harness is shorted between circuits.
10		No	Go to the next step.
11	INSPECT CAN LINE BETWEEN SAS CONTROL MODULE AND CONNECTORS C-55, C-56 FOR SHORT BETWEEN CIRCUITS Measure the voltage at PCM terminals 2S and 2T. Is the voltage at PCM terminals 2S and 2T the same?	Yes	Repair or replace the wiring harness between the connectors C-55, C-56 and connector C-21 because the wiring harness is shorted between circuits.
11		No	Go to the next step.
12	INSPECT SAS CONTROL MODULE FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the SAS control module connector. Inspect for continuity between SAS control module terminals 3A and 3D (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the SAS control module and connectors C-55, C-56 because the wiring harness is shorted between circuits.
12		No	Replace the SAS control module because there is a short between circuits in the SAS control module. (See SAS CONTROL MODULE REMOVAL/INSTALLATION [TWO-STEP DEPLOYMENT CONTROL SYSTEM - US/CANADA SPEC.] .)
13	INSPECT CAN LINE BETWEEN CONNECTOR C-07 AND CONNECTOR C-21 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector C-07. Connect the connector C-21. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between connector C-07 and connector C-21 because the wiring harness is shorted between circuits.
13		No	Go to the next step. (SKYACTIV-G 2.0, SKYACTIV-G 2.5 with connectors C-37, C-36) Go to Step 18. (SKYACTIV-G 2.0, SKYACTIV-G 2.5 without connectors C-37, C-36)
14	INSPECT CAN LINE BETWEEN CONNECTORS C-37, C-36 AND CONNECTOR C-07 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connectors C-37, C-36. Connect the connector C-07. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between the connectors C-37, C-36 and connector C-07 because the wiring harness is shorted between circuits.
14		No	Go to the next step.
15	INSPECT CAN LINE BETWEEN DSC HU/CM AND CONNECTORS C-37, C-36 FOR SHORT BETWEEN CIRCUITS Inspect for continuity between DSC HU/CM terminals L and J. Is there continuity?	Yes	Go to the next step.
15		No	Go to Step 17.
16	INSPECT DSC HU/CM FOR SHORT BETWEEN CIRCUITS Disconnect the DSC HU/CM connector. Inspect for continuity between DSC HU/CM terminals L and J (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the DSC HU/CM and connectors C-37, C-36 because the wiring harness is shorted between circuits.
16		No	Replace the DSC HU/CM because there is a short between circuits in the DSC HU/CM. (See DSC HU/CM REMOVAL/INSTALLATION [L.H.D. (US)] .)
17	INSPECT CAN LINE BETWEEN CONNECTORS C-37, C-36 AND CONNECTOR C-02 FOR SHORT BETWEEN CIRCUITS Disconnect the connector C-02. Connect the connectors C-37, C-36. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between the connectors C-37, C-36 and connector C-02 because the wiring harness is shorted between circuits.
17		No	Go to Step 20. (ATX) Go to Step 24. (MTX)
18	INSPECT CAN LINE BETWEEN CONNECTOR C-02 AND CONNECTOR C-07 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector C-02. Connect the connector C-07. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Go to the next step.
18		No	Go to Step 20. (ATX) Go to Step 24. (MTX)
19	INSPECT DSC HU/CM FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the DSC HU/CM connector. Inspect for continuity between DSC HU/CM terminals L and J (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between connector C-07 and connector C-02 because the wiring harness is shorted between circuits.
19		No	Replace the DSC HU/CM because there is a short between circuits in the DSC HU/CM. (See DSC HU/CM REMOVAL/INSTALLATION [L.H.D. (US)] .)
20	INSPECT CAN LINE BETWEEN CONNECTOR C-38 AND CONNECTOR C-02 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector C-38. Connect the connector C-02. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between connector C-38 and connector C-02 because the wiring harness is shorted between circuits.
20		No	Go to the next step.
21	INSPECT CAN LINE BETWEEN TCM AND CONNECTOR C-38 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Inspect for continuity between TCM terminals E and F. Is there continuity?	Yes	Go to the next step.
21		No	Go to Step 23.
22	INSPECT TCM FOR SHORT BETWEEN CIRCUITS Disconnect the TCM connector. Inspect for continuity between TCM terminals E and F (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the TCM and connector C-38 because the wiring harness is shorted between circuits.
22		No	Replace the TCM because there is a short between circuits in the TCM. (See CONTROL VALVE BODY REMOVAL/INSTALLATION [ET6A-EL, ET6AX-EL (US)] .) (See CONTROL VALVE BODY REMOVAL/INSTALLATION [EV6A-EL, EV6AX-EL (US)] .)
23	INSPECT CAN LINE BETWEEN CONNECTOR C-38 AND CONNECTOR C-01 FOR SHORT BETWEEN CIRCUITS Disconnect the connector C-01. Connect the connector C-38. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between connector C-01 and connector C-38 because the wiring harness is shorted between circuits.
23		No	Go to Step 25.
24	INSPECT CAN LINE BETWEEN CONNECTOR C-02 AND CONNECTOR C-01 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Connect the connector C-02. Disconnect the connector C-01. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Repair or replace the wiring harness between connector C-02 and connector C-01 because the wiring harness is shorted between circuits.
24		No	Go to the next step.
25	INSPECT PCM FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the PCM connector. Inspect for continuity between PCM terminals 2S and 2T (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the PCM and connector C-01 because the wiring harness is shorted between circuits.
25		No	Replace the PCM because there is a short between circuits in the PCM. (See PCM REMOVAL/INSTALLATION (VIN M) .) (See PCM REMOVAL/INSTALLATION (VIN L) .)
26	INSPECT CAN LINE BETWEEN CONNECTORS C-37, C-36 AND CONNECTOR C-07 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connectors C-37, C-36. Connect the connector C-07. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off). Measure the voltage at body control module (BCM) terminals 3X and 3W. Is the voltage at body control module (BCM) terminals 3X and 3W the same?	Yes	Go to the next step.
26		No	Go to Step 29.
27	INSPECT CAN LINE BETWEEN TCM AND CONNECTOR C-02 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector C-02. Inspect for continuity between TCM terminals E and F. Is there continuity?	Yes	Go to the next step.
27		No	Repair or replace the wiring harness between connector C-07 and connector C-02 and connectors C-37, C-36 because the wiring harness is shorted between circuits.
28	INSPECT TCM FOR SHORT BETWEEN CIRCUITS Disconnect the TCM connector. Inspect for continuity between TCM terminals E and F (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the TCM and connector C-02 because the wiring harness is shorted between circuits.
28		No	Replace the TCM because there is a short between circuits in the TCM. (See CONTROL VALVE BODY REMOVAL/INSTALLATION [ET6A-EL, ET6AX-EL (US)] .) (See CONTROL VALVE BODY REMOVAL/INSTALLATION [EV6A-EL, EV6AX-EL (US)] .)
29	INSPECT CAN LINE BETWEEN DSC HU/CM AND CONNECTORS C-37, C-36 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Inspect for continuity between DSC HU/CM terminals L and J. Is there continuity?	Yes	Go to the next step.
29		No	Go to Step 31.
30	INSPECT DSC HU/CM FOR SHORT BETWEEN CIRCUITS Disconnect the DSC HU/CM connector. Inspect for continuity between DSC HU/CM terminals L and J (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the DSC HU/CM and connectors C-37, C-36 because the wiring harness is shorted between circuits.
30		No	Replace the DSC HU/CM because there is a short between circuits in the DSC HU/CM. (See DSC HU/CM REMOVAL/INSTALLATION [L.H.D. (US)] .)
31	INSPECT PCM FOR SHORT BETWEEN CIRCUITS Disconnect the PCM connector. Inspect for continuity between PCM terminals 2S and 2T (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the PCM and connectors C-37, C-36 because the wiring harness is shorted between circuits.
31		No	Replace the PCM because there is a short between circuits in the PCM.
32	INSPECT CAN LINE BETWEEN TCM AND CONNECTOR C-02 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the connector C-02. Inspect for continuity between TCM terminals E and F. Is there continuity?	Yes	Go to the next step.
32		No	Go to Step 34.
33	INSPECT TCM FOR SHORT BETWEEN CIRCUITS Disconnect the TCM connector. Inspect for continuity between TCM terminals E and F (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the TCM and connector C-02 because the wiring harness is shorted between circuits.
33		No	Replace the TCM because there is a short between circuits in the TCM. (See CONTROL VALVE BODY REMOVAL/INSTALLATION [ET6A-EL, ET6AX-EL (US)] .) (See CONTROL VALVE BODY REMOVAL/INSTALLATION [EV6A-EL, EV6AX-EL (US)] .)
34	INSPECT DSC HU/CM FOR SHORT BETWEEN CIRCUITS Disconnect the DSC HU/CM connector. Inspect for continuity between DSC HU/CM terminals L and J. Is there continuity?	Yes	Replace the DSC HU/CM because there is a short between circuits in the DSC HU/CM. (See DSC HU/CM REMOVAL/INSTALLATION [L.H.D. (US)] .)
34		No	Go to the next step.
35	INSPECT PCM FOR SHORT BETWEEN CIRCUITS Disconnect the PCM connector. Inspect for continuity between PCM terminals 2S and 2T (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the PCM and the DSC HU/CM and connector C-02 and connector C-07 because the wiring harness is shorted between circuits.
35		No	Replace the PCM because there is a short between circuits in the PCM.