DTC U0401:00 [INTEGRATED STARTER GENERATOR (ISG)]

id140202302000

Outline

System malfunction location	Error signal received from PCM
Detection condition	Determination conditions	•  The integrated starter generator (ISG) receives an error signal from the PCM for 1 s.
	Precondition	•  1.5 s have elapsed after the ignition was switched ON (engine off or on) •  The initialization for the stator coil drive circuit in the integrated starter generator (ISG) is completed. •  The voltage at terminal 1A is 10 V or more for a continuous 1.5 s.
Fail-safe	•  Stops power supply from the Mazda M Hybrid battery and supplies power to the vehicle’s electrical devices (12 V power supply) from the 12 V battery.(If the vehicle continues to be driven while the DTC is detected, the 12 V battery will be depleted and the vehicle can no longer be driven.) •  Inhibits the i-stop control. •  Inhibits the non-power generation control. •  Inhibits regenerative braking by the ISG. •  Inhibits motor assist control by the ISG.
Possible cause	•  PCM malfunction •  Integrated starter generator (ISG) malfunction
System wiring diagram	•  Not applicable
Connector diagram	•  Not applicable

Diagnostic Procedure

Step	Inspection	Results	Action
1	RECORD VEHICLE STATUS WHEN DTC WAS DETECTED TO UTILIZE WITH REPEATABILITY VERIFICATION •  Record the snapshot data. Note •  Recording can be facilitated using the screen capture function of the PC.	—	Go to the next step.
2	VERIFY PCM DTC •  Perform the DTC inspection for the PCM. (See DTC INSPECTION.) •  Are any DTCs displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [PCM (SKYACTIV-G (E))].) (See DTC TABLE [PCM (SKYACTIV-X)].)
		No	Go to the next step.
3	INSPECT PCM FOR MALFUNCTION DEPENDING ON REPEATABILITY •  Install/connect the part removed/disconnected during the troubleshooting procedure. •  Clear the DTC recorded in the memory. (See CLEARING DTC.) •  Switch the ignition off, then ON (engine off). •  Perform the DTC inspection for the integrated starter generator (ISG). (See DTC INSPECTION.) •  Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW [(E)].) If the CAN communication is normal, perform the diagnosis from Step 1. •  If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (E))].) (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (E))].) (See PCM REMOVAL/INSTALLATION [SKYACTIV-X 2.0].) Go to repair completion verification 1.
		No	Go to the next step.
4	INSPECT PCM FOR MALFUNCTION DEPENDING ON REPEATABILITY AGAIN •  Perform the "Action for Non-repeatable Malfunction" procedure. (See TROUBLESHOOTING PROCEDURE [(E)].) •  Perform the DTC inspection for the integrated starter generator (ISG). (See DTC INSPECTION.) •  Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW [(E)].) If the CAN communication is normal, perform the diagnosis from Step 1. •  If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (E))].) (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (E))].) (See PCM REMOVAL/INSTALLATION [SKYACTIV-X 2.0].) Go to repair completion verification 1.
		No	If noise is applied to communication, a DTC may be displayed. •  Go to repair completion verification 2.
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. (See CLEARING DTC.) •  Replicate the vehicle conditions at the time the DTC was detected using the following procedure. ―  Switch the ignition off, then ON (engine off). •  Perform the DTC inspection for the integrated starter generator (ISG). (See DTC INSPECTION.) •  Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW [(E)].) If the CAN communication is normal, perform the diagnosis from Step 1. •  If the malfunction recurs, replace the integrated starter generator (ISG), then go to the next step. (See INTEGRATED STARTER GENERATOR (ISG) REMOVAL/INSTALLATION [SKYACTIV-G].) (See INTEGRATED STARTER GENERATOR (ISG) REMOVAL/INSTALLATION [SKYACTIV-X 2.0].)
		No	Go to the next step.
Repair completion verification 2	VERIFY IF OTHER DTCs DISPLAYED •  Perform the DTC inspection. (See DTC INSPECTION.) •  Are any other DTCs displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting.
		No	DTC troubleshooting completed.