DTC U0401:68 [DC-DC CONVERTER (Mazda M Hybrid)]
id140206302200
Outline
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System malfunction location |
Error signal received from PCM |
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Detection condition
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• The DC-DC converter (Mazda M Hybrid) receives an error signal from the PCM.
Precondition
• 1.5 s have elapsed after the ignition was switched ON (engine off or on)
• Voltage at DC-DC converter (Mazda M Hybrid) terminal 1A is 9-16 V for a continuous 1 s
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Fail-safe
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• Inhibits the i-stop control.
• Inhibits the non-power generation control.
• Inhibits regenerative braking by the integrated starter generator (ISG).
• Inhibits motor assist control by the integrated starter generator (ISG).
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Possible cause
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• PCM malfunction
• DC-DC converter (Mazda M Hybrid) malfunction
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System wiring diagram
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• Not applicable
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Connector diagram
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• Not applicable
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Diagnostic Procedure
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Step |
Inspection |
Results |
Action |
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1
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RECORD VEHICLE STATUS WHEN DTC WAS DETECTED TO UTILIZE WITH REPEATABILITY VERIFICATION
• Record the snapshot data.
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—
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Go to the next step.
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2
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INSPECT FOR OTHER RELATED DTCs
• Perform the DTC inspection for the DC-DC converter (Mazda M Hybrid).
(See DTC INSPECTION.)
• Are any of the following DTCs displayed?
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Yes
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Repair the malfunctioning location according to the applicable DTC troubleshooting.
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No
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Go to the next step.
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3
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VERIFY PCM DTC
• Perform the DTC inspection for the PCM.
(See DTC INSPECTION.)
• Are any DTCs displayed?
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Yes
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Repair the malfunctioning location according to the applicable DTC troubleshooting.
(See DTC TABLE [PCM (SKYACTIV-G)].)
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No
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Go to the next step.
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4
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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 DC-DC converter (Mazda M Hybrid).
(See DTC INSPECTION.)
• Is the same Pending DTC present?
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Yes
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Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error.
If the CAN communication is normal, perform the diagnosis from Step 1.
• If the malfunction recurs, replace the PCM.
Go to repair completion verification 1.
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No
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Go to the next step.
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5
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INSPECT PCM FOR MALFUNCTION DEPENDING ON REPEATABILITY AGAIN
• Perform the "Action for Non-repeatable Malfunction" procedure.
• Perform the DTC inspection for the DC-DC converter (Mazda M Hybrid).
(See DTC INSPECTION.)
• Is the same Pending DTC present?
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Yes
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Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error.
If the CAN communication is normal, perform the diagnosis from Step 1.
• If the malfunction recurs, replace the PCM.
Go to repair completion verification 1.
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No
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The system is normal. (Explain to the customer that a malfunction was detected temporarily, but the vehicle is currently normal.)
Go to repair completion verification 2.
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Repair completion verification 1
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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.)
• Switch the ignition off, then ON (engine off).
• Perform the DTC inspection for the DC-DC converter (Mazda M Hybrid).
(See DTC INSPECTION.)
• Is the same Pending DTC present?
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Yes
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Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error.
If the CAN communication is normal, perform the diagnosis from Step 1.
• If the malfunction recurs, replace the DC-DC converter (Mazda M Hybrid), then go to the next step.
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No
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Go to the next step.
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Repair completion verification 2
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VERIFY IF OTHER DTCs DISPLAYED
• Perform the DTC inspection.
(See DTC INSPECTION.)
• Are any other DTCs displayed?
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Yes
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Repair the malfunctioning location according to the applicable DTC troubleshooting.
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No
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DTC troubleshooting completed.
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