Diagnostic 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.

DTC U0187:00 (CONNECTIVITY MASTER UNIT) DIAGNOSTIC PROCEDURE

Step	Inspection	Results	Action
1	VERIFY REPEATABILITY Switch the ignition ON (engine off or on). Clear the DTC recorded in the memory. (Refer to the [CLEARING DTC] in the appropriate service information) Because the connectivity master unit (CMU) is in sleep mode, perform the following operation. Switch the ignition OFF. Remove all of the remote transmitters from the vehicle, lock all doors, and then wait for 10 min. Perform the DTC inspection for the connectivity master unit (CMU). (Refer to the [DTC INSPECTION] in the appropriate service information) Is the same Pending DTC present?	Yes	Go to the next step.
1		No	Go to repair completion verification 2.
2	INSPECT DVD/CD PLAYER CONNECTOR FOR MALFUNCTION Inspect the applicable connector and terminal. (Refer to the [CONNECTOR INSPECTION] in the appropriate service information) Are the connector and terminal normal?	Yes	Go to the next step.
2		No	Repair or replace the malfunctioning location and perform the repair completion verification.
3	VERIFY SUPPLY VOLTAGE TO DVD/CD PLAYER Measure the voltage at DVD/CD player terminal 1A (vehicle wiring harness side). Is the voltage B+?	Yes	Go to Step 5.
3		No	Go to the next step.
4	INSPECT DVD/CD PLAYER POWER SUPPLY CIRCUIT (B+) FOR SHORT TO GROUND AND OPEN CIRCUIT Inspect power supply circuit for short to ground and an open circuit. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning location and perform the repair completion verification.
5	INSPECT DVD/CD PLAYER GROUND CIRCUIT FOR OPEN CIRCUIT Inspect the applicable circuit for an open circuit. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Go to the next step.
5		No	Repair or replace the malfunctioning location and perform the repair completion verification.
6	VERIFY DVD/CD PLAYER ACC POWER SUPPLY VOLTAGE Switch the ignition to ACC. Measure the voltage at DVD/CD player terminal 1B (vehicle wiring harness side). Is the voltage B+?	Yes	Replace the DVD/CD player and perform the repair completion verification. (Refer to the [DVD/CD PLAYER REMOVAL/INSTALLATION] in the appropriate service information)
6		No	Go to the next step.
7	INSPECT DVD/CD PLAYER POWER SUPPLY CIRCUIT (ACC) FOR SHORT TO GROUND Inspect the applicable circuit for a short to ground. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning location and perform the repair completion verification.
8	INSPECT DVD/CD PLAYER POWER SUPPLY CIRCUIT (ACC) FOR OPEN CIRCUIT Inspect the applicable circuit for an open circuit. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Go to the next step.
8		No	Repair or replace the malfunctioning location and perform the repair completion verification.
9	VERIFY CONNECTIVITY MASTER UNIT (CMU) ACC POWER SUPPLY VOLTAGE Switch the ignition to ACC. Measure the voltage at connectivity master unit (CMU) terminal 1S. Is the voltage B+?	Yes	Go to the next step.
9		No	Replace the connectivity master unit (CMU) and perform the repair completion verification. (Refer to the [CONNECTIVITY MASTER UNIT (CMU) REMOVAL/INSTALLATION] in the appropriate service information)
10	INSPECT CONNECTIVITY MASTER UNIT (CMU) CONNECTOR FOR MALFUNCTION Inspect the applicable connector and terminal. (Refer to the [CONNECTOR INSPECTION] in the appropriate service information) Are the connector and terminal normal?	Yes	Go to the next step.
10		No	Repair or replace the malfunctioning location and perform the repair completion verification.
11	INSPECT USB CIRCUIT BETWEEN CONNECTIVITY MASTER UNIT (CMU) AND DVD/CD PLAYER FOR SHORT TO GROUND Inspect the applicable circuit for a short to ground. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Go to the next step.
11		No	Repair or replace the malfunctioning location and perform the repair completion verification.
12	INSPECT USB CIRCUIT BETWEEN CONNECTIVITY MASTER UNIT (CMU) AND DVD/CD PLAYER FOR SHORT TO POWER SUPPLY Inspect the applicable circuit for a short to power supply. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Go to the next step.
12		No	Repair or replace the malfunctioning location and perform the repair completion verification.
13	INSPECT USB CIRCUIT BETWEEN CONNECTIVITY MASTER UNIT (CMU) AND DVD/CD PLAYER FOR OPEN CIRCUIT Inspect the applicable circuit for an open circuit. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is the circuit normal?	Yes	Go to the next step.
13		No	Repair or replace the malfunctioning location and perform the repair completion verification.
14	INSPECT SHIELDING USB CIRCUIT BETWEEN CONNECTIVITY MASTER UNIT (CMU) AND DVD/CD PLAYER Inspect the applicable circuit for continuity with the body ground. (Refer to the [CIRCUIT INSPECTION] in the appropriate service information) Is there continuity?	Yes	Go to the next step.
14		No	Repair or replace the malfunctioning location and perform the repair completion verification.
15	VERIFY CONNECTIVITY MASTER UNIT (CMU) DTCs Clear the DTC recorded in the memory. (Refer to the [CLEARING DTC] in the appropriate service information) Perform the DTC inspection for the connectivity master unit (CMU). (Refer to the [DTC INSPECTION] in the appropriate service information) Are other DTCs displayed?	Yes	Replace the connectivity master unit (CMU) and perform the repair completion verification. (Refer to the [CONNECTIVITY MASTER UNIT (CMU) REMOVAL/INSTALLATION] in the appropriate service information)
15		No	Replace the DVD/CD player and perform the repair completion verification. (Refer to the [DVD/CD PLAYER REMOVAL/INSTALLATION] in the appropriate service information)
Repair completion verification 1	VERIFY THAT VEHICLE IS REPAIRED Install/connect the part removed/disconnected during the troubleshooting procedure. Clear the DTC recorded in the memory. (Refer to the [CLEARING DTC] in the appropriate service information) Because the connectivity master unit (CMU) is in sleep mode, perform the following operation. Switch the ignition OFF. Remove all of the remote transmitters from the vehicle, lock all doors, and then wait for 10 min. Perform the DTC inspection for the connectivity master unit (CMU). (Refer to the [DTC INSPECTION] in the appropriate service information) Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (Refer to the [CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW] in the appropriate service information) If the CAN communication is normal, perform the diagnosis from Step 1. If the malfunction recurs, replace the connectivity master unit (CMU), then go to the next step. (Refer to the [CONNECTIVITY MASTER UNIT (CMU) REMOVAL/INSTALLATION] in the appropriate service information)
Repair completion verification 1		No	Go to the next step.
Repair completion verification 2	VERIFY IF OTHER DTCs ARE DISPLAYED Perform the DTC inspection. (Refer to the [DTC INSPECTION] in the appropriate service information) Is a DTC displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting.
Repair completion verification 2		No	DTC troubleshooting completed.