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Q5/X451 FATC
DTC Troubleshooting Data
Version: 1.0
Date: 16-Oct-2018
Copyright ©
TATA MOTORS Ltd.
This document must not be used in any way, such as copying and redistributing to third parties, without the consent of author.
Author: ERC
Page: 196 of 202
U0401-81:- Invalid Data Received From ECM
Overview:
ISO Code
U0401-81
Customer Symptom
Reduced climate functionality and performance. Cooling does not happen as per
user set temperature request.
Fault Effects (On Vehicle)
1)
Accurate heating/Cooling cannot be achieved
2)
Cold start compensation for Blower and Air distribution will not be
possible
Lamp Status (If Any)
1) The value of signal "EMS_Invalid_Failure_Status" in supervision frame is
changes from '0' to '1'.
2) Invalid Data Received from ECM/PCM "A" DTC is in active state in fault
memory.
3) The HVAC outputs (motors and compressor request signal) is functional using
default data values where CAN data not available
4) CAN communication is normal.
5) The value of signal "EMS_Invalid_Failure_Status" in supervision frame is '1' to
'2'.
6) Invalid Data Received from ECM/PCM "A" DTC is in passive state in fault
memory.
7) The HVAC outputs (motors and compressor request signal) is functional using
acutal data values of CAN message from ECM node.
8) CAN communication is normal.
Fault Detection Condition
Relevant functional DTCs present in ECM
Normal Operating
Condition
ECM ECU sends correct data in normal condition.
Probable Trouble Area
Incorrect data received from ECM.
Healing Condition
After rectifying relevant functional failures in the ECM
ECU