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.

ERROR IS DISPLAYED ON VEHICLE IDENTIFICATION (VEHICLE INFORMATION ACQUISITION) SCREEN (US) - DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	INSPECT FOR SHORT TO GROUND IN CAN-BUS NO. 1 Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US)) Inspect for continuity at the following terminals: Between body control module (BCM) terminal 3X and body ground Between body control module (BCM) terminal 3W and body ground Is there continuity?	Yes	Short to ground in CAN-BUS No. 1 has occurred. Determine the location of a short to ground according to the diagnosis procedure for determining the location of a short to ground in CAN-BUS No. 1. (See DETERMINING SHORT TO GROUND LOCATION (CAN-BUS No. 1) (US))
1		No	Go to the next step.
2	INSPECT FOR SHORT TO POWER SUPPLY IN CAN-BUS No. 1 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) terminal 3X and 3W. Is the voltage between 1.5-3.5 V?	Yes	Go to the next step.
2		No	Short to power supply in CAN-BUS No. 1 has occurred. Determine the location of a short to power supply according to the diagnosis procedure for determining the location of a short to power supply in CAN-BUS No. 1. (See DETERMINING SHORT TO POWER SUPPLY LOCATION (CAN-BUS No. 1) (US))
3	INSPECT FOR SHORT BETWEEN CIRCUITS IN CAN-BUS No. 1 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	Short between circuits in CAN-BUS No. 1 has occurred. Determine the location of a short between circuits according to the diagnosis procedure for determining the location of a short between circuits in CAN-BUS No. 1. (See DETERMINING SHORT BETWEEN CIRCUITS LOCATION (CAN-BUS No. 1) (US))
3		No	Go to the next step.
4	INSPECT FOR OPEN CIRCUIT IN THE WIRING HARNESS BETWEEN PCM AND BODY CONTROL MODULE (BCM) Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Disconnect the EPS control module connector. Disconnect the adaptive front lighting system (AFS) control module connector. Disconnect the SAS control module connector. Disconnect the DSC HU/CM connector. Disconnect the TCM connector. Inspect for continuity at the following terminals: Between PCM terminal 2S and body control module (BCM) terminals 3X Between PCM terminal 2T and body control module (BCM) terminals 3W Is there continuity?	Yes	Because the circuit between the PCM and body control module (BCM) is currently normal, go back to the [TROUBLESHOOTING PROCEDURE].
4		No	Any of the following malfunctions may have occurred. Repair or replace the wiring harness because there is an open circuit in the wiring harness between PCM terminal 2S and body control module (BCM) terminal 3X. Repair or replace the wiring harness because there is an open circuit in the wiring harness between PCM terminal 2T and body control module (BCM) terminal 3W. 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) .) Replace the PCM because there is a short to ground in the PCM. (See PCM REMOVAL/INSTALLATION (VIN M) .) (See PCM REMOVAL/INSTALLATION (VIN L) .)