Diagnostic Procedure

DTC U0198:00 (AUDIO CONTROL UNIT (ACU)) 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) Switch the ignition OFF, and then switch it ON (engine off or on) and wait for 30 s or more. Perform the DTC inspection for the audio control unit (ACU). (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 Mazda EMERGENCY ASSISTANCE CONTROL MODULE FOR MALFUNCTION Perform the DTC inspection for the Mazda EMERGENCY ASSISTANCE control module. (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. (Refer to the [DTC TABLE [Mazda EMERGENCY ASSISTANCE CONTROL MODULE]] in the appropriate service information )
2		No	Go to the next step.
3	VERIFY Mazda EMERGENCY ASSISTANCE CONTROL MODULE POWER SUPPLY VOLTAGE Measure the voltage at Mazda EMERGENCY ASSISTANCE control module terminal 1AF (vehicle wiring harness side). Is voltage supplied?	Yes	Go to Step 7.
3		No	Go to the next step.
4	INSPECT Mazda EMERGENCY ASSISTANCE CONTROL MODULE 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.
4		No	Repair or replace the malfunctioning location and perform the repair completion verification.
5	INSPECT Mazda EMERGENCY ASSISTANCE CONTROL MODULE POWER SUPPLY CIRCUIT FOR SHORT TO GROUND AND OPEN CIRCUIT Inspect the power supply circuit for a short to ground and 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	INSPECT Mazda EMERGENCY ASSISTANCE CONTROL MODULE 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.
6		No	Repair or replace the malfunctioning location and perform the repair completion verification.
7	INSPECT Mazda EMERGENCY ASSISTANCE CONTROL MODULE 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.
7		No	Repair or replace the malfunctioning location and perform the repair completion verification.
8	INSPECT AUDIO CONTROL UNIT (ACU) 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.
8		No	Repair or replace the malfunctioning location and perform the repair completion verification.
9	INSPECT CIRCUIT BETWEEN AUDIO CONTROL UNIT (ACU) AND Mazda EMERGENCY ASSIST EMERGENCY ASSISTANCE CONTROL MODULE 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.
9		No	Repair or replace the malfunctioning location and perform the repair completion verification.
10	INSPECT CIRCUIT BETWEEN AUDIO CONTROL UNIT (ACU) AND Mazda EMERGENCY ASSISTANCE CONTROL MODULE 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.
10		No	Repair or replace the malfunctioning location and perform the repair completion verification.
11	INSPECT CIRCUIT BETWEEN AUDIO CONTROL UNIT (ACU) AND Mazda EMERGENCY ASSISTANCE CONTROL MODULE 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.
11		No	Repair or replace the malfunctioning location and perform the repair completion verification.
12	INSPECT SHIELDING CIRCUIT BETWEEN AUDIO CONTROL UNIT (ACU) AND Mazda EMERGENCY ASSISTANCE CONTROL MODULE 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.
12		No	Repair or replace the malfunctioning location and perform the repair completion verification.
13	DETERMINE MALFUNCTIONING LOCATION Clear the DTC recorded in the memory. (Refer to the [CLEARING DTC ] in the appropriate service information) Perform the DTC inspection for the audio control unit (ACU). (Refer to the [DTC INSPECTION ] in the appropriate service information) Are other DTCs displayed that are the same as this DTC?	Yes	Replace the audio control unit (ACU) and perform the repair completion verification. (Refer to the [AUDIO CONTROL UNIT (ACU) REMOVAL/INSTALLATION ] in the appropriate service information)
13		No	Replace the Mazda EMERGENCY ASSISTANCE control module and perform the repair completion verification. (Refer to the [Mazda EMERGENCY ASSISTANCE CONTROL MODULE 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) Perform the DTC inspection for the audio control unit (ACU). (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 audio control unit (ACU), then go to the next step. (Refer to the [AUDIO CONTROL UNIT (ACU) 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) Are other DTCs displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting.
Repair completion verification 2		No	DTC troubleshooting completed.