DTC U0401:00 [RADAR UNIT]

id1502a6019200

Description	Error signal received from PCM
Detection condition	•  Communication error between PCM and radar unit
Fail-safe	•  Inhibits the Mazda radar cruise control (MRCC) system control
Possible cause	•  DTCs are stored in the PCM. ―  PCM 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 the next step.
		No	Go to the next step.
2	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.
3	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.