Diagnostic Procedure

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

NO SOUND OUTPUT IN MULTIPLE MODES (ENTERTAINMENT SYSTEM - WITH CENTER DISPLAY) - DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	INSPECT TAU CONNECTOR Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Disconnect the TAU connector. Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. Is the connector normal?	Yes	Go to the next step.
1		No	Repair or replace the connector, then go to Step 7.
2	INSPECT CMU CONNECTOR Disconnect the CMU connector. Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. Is the connector normal?	Yes	Go to the next step.
2		No	Repair or replace the connector, then go to Step 7.
3	VERIFY IF MALFUNCTION CAUSE IS OPEN CIRCUIT IN WIRING HARNESS BETWEEN CMU AND TAU Verify that the CMU and TAU connectors are disconnected. Inspect the wiring harness for continuity between the following terminals (vehicle wiring harness side). CMU terminal 1Y and TAU terminal 1Q CMU terminal 1Z and TAU terminal 1R CMU terminal 1AA and TAU terminal 1S CMU terminal 1AB and TAU terminal 1T Is there continuity?	Yes	Go to the next step.
3		No	Refer to the wiring diagram and verify if there is a common connector between the following terminals. CMU terminal 1Y and TAU terminal 1Q CMU terminal 1Z and TAU terminal 1R CMU terminal 1AA and TAU terminal 1S CMU terminal 1AB and TAU terminal 1T If there is a common connector: Inspect the common connector and terminals for corrosion, damage, or disconnection and the common wiring harnesses for an open circuit to determine the malfunctioning location. Repair or replace the malfunctioning location. If there is no common connector: Repair or replace the wiring harness which has an open circuit. Go to Step 7.
4	VERIFY IF MALFUNCTION CAUSE IS SHORT TO GROUND IN WIRING HARNESS BETWEEN CMU AND TAU Verify that the CMU and TAU connectors are disconnected. Inspect for continuity between the following wiring harness terminals (vehicle wiring harness side) and body ground. TAU terminal 1Q TAU terminal 1R TAU terminal 1S TAU terminal 1T Is there continuity?	Yes	Refer to the wiring diagram and verify if there is a common connector between the following terminals. CMU terminal 1Y and TAU terminal 1Q CMU terminal 1Z and TAU terminal 1R CMU terminal 1AA and TAU terminal 1S CMU terminal 1AB and TAU terminal 1T If there is a common connector: Inspect the common connector and terminals for corrosion, damage, or disconnection and the common wiring harnesses for short to ground to determine the malfunctioning location. Repair or replace the malfunctioning location. If there is no common connector: Repair or replace the wiring harness which is shorted to ground. Go to Step 7.
4		No	Go to the next step.
5	VERIFY IF MALFUNCTION CAUSE IS SHORT TO POWER SUPPLY IN WIRING HARNESS BETWEEN CMU AND TAU Verify that the CMU and TAU connectors are disconnected. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Switch the ignition to ACC or ON (engine off or on). Measure the voltage at the following terminals (vehicle wiring harness side). TAU terminal 1Q TAU terminal 1R TAU terminal 1S TAU terminal 1T Is the voltage B+?	Yes	Refer to the wiring diagram and verify if there is a common connector between the following terminals. CMU terminal 1Y and TAU terminal 1Q CMU terminal 1Z and TAU terminal 1R CMU terminal 1AA and TAU terminal 1S CMU terminal 1AB and TAU terminal 1T If there is a common connector: Inspect the common connector and terminals for corrosion, damage, or disconnection and the common wiring harnesses for an open circuit to determine the malfunctioning location. Repair or replace the malfunctioning location. If there is no common connector: Repair or replace the wiring harness which is shorted to the power supply. Go to Step 7.
5		No	Go to the next step.
6	DETERMINE IF MALFUNCTION CAUSE IS TAU Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Replace the TAU. (See TUNER AND AMP UNIT (TAU) REMOVAL/INSTALLATION .) Connect all the connectors. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Switch the ignition to ACC or ON (engine off or on). Select the mode when the malfunction occurred by operating the center display or the commander switch. Is audio output normally?	Yes	Go to the next step.
6		No	Replace the CMU, then go to the next step. (See CONNECTIVITY MASTER UNIT (CMU) REMOVAL/INSTALLATION .)
7	VERIFY IF MALFUNCTION CAUSE IS CORRECTED Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Connect all the connectors. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Switch the ignition to ACC or ON (engine off or on). Select the mode when the malfunction occurred by operating the center display or the commander switch. Is audio output normally?	Yes	Troubleshooting completed. (Explain the contents of the servicing to the customer.)
7		No	Verify the malfunction symptom in the symptom troubleshooting chart and perform the other applicable malfunction diagnosis. (See SYMPTOM TROUBLESHOOTING [ENTERTAINMENT SYSTEM [WITH CENTER DISPLAY]] .)