DTC U0301:09 [RADAR UNIT]

id1502a6018800

Description	Error signal received from PCM
Detection condition	•  Radar unit receives the following signals from the PCM. ―  Brake switch error signal ―  Cruise control switch error signal ―  PCM internal malfunction signal ―  Cruise control error signal ―  Engine speed error signal ―  Accelerator opening angle error signal
Fail-safe	•  Inhibits the Mazda radar cruise control (MRCC) system control •  Inhibits the smart brake support (SBS) system control*1 •  Inhibits the distance recognition support system (DRSS) control*1 *1: Enabled depending on malfunction content.
Possible cause	•  DTCs are stored in the PCM. ―  PCM malfunction •  DTCs are stored in the DSC HU/CM. ―  DSC HU/CM malfunction •  Radar unit malfunction
System wiring diagram	Not applicable

Diagnostic Procedure

Step	Inspection		Action
1	PERFORM DTC INSPECTION FOR PCM •  Perform the PCM DTC inspection using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-D 2.2)].) (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.5T)].) (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))].) (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5 (WITHOUT CYLINDER DEACTIVATION))].) •  Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [PCM (SKYACTIV-D 2.2)].) (See DTC TABLE [PCM (SKYACTIV-G 2.5T)].) (See DTC TABLE [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))].) (See DTC TABLE [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5 (WITHOUT CYLINDER DEACTIVATION))].) Go to Step 4.
		No	Go to the next step.
2	PERFORM DTC INSPECTION FOR DSC HU/CM •  Perform the DSC HU/CM DTC inspection using the M-MDS. (See DTC INSPECTION [DYNAMIC STABILITY CONTROL (DSC)].) •  Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [DYNAMIC STABILITY CONTROL (DSC)].) Go to Step 4.
		No	Go to the next step.
3	VERIFY IF MALFUNCTIONING LOCATION IS DSC HU/CM DEPENDING ON REPEATABILITY •  Clear radar unit DTCs using the M-MDS. (See CLEARING DTC [RADAR UNIT].) •  Switch the ignition ON (engine on). •  Perform the radar unit DTC inspection using the M-MDS. (See DTC INSPECTION [RADAR UNIT].) •  Is the same Pending DTC present?	Yes	Replace the DSC HU/CM, then go to the next step. (See DSC HU/CM REMOVAL/INSTALLATION.)
		No	Go to the next step.
4	VERIFY THAT REPAIRS HAVE BEEN COMPLETED •  Clear radar unit DTCs using the M-MDS. (See CLEARING DTC [RADAR UNIT].) •  Switch the ignition ON (engine on). •  Perform the radar unit DTC inspection using the M-MDS. (See DTC INSPECTION [RADAR UNIT].) •  Is the same Pending DTC present?	Yes	Repeat the inspection from Step 1. •  If the malfunction does not recur, go to the next step. •  If the malfunction recurs, replace the radar unit. (See RADAR UNIT REMOVAL/INSTALLATION.) Go to the next step.
		No	Go to the next step.
5	VERIFY THAT NO OTHER DTCs ARE PRESENT •  Verify other DTCs displayed. •  Are any other DTCs output?	Yes	Perform the corresponding DTC inspection.
		No	DTC troubleshooting completed.