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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: 164 of 202
U0028-88:- Vehicle Communication Bus A-Bus off
Overview:
ISO Code
U0028-88
Customer Symptom
EPAS lamp ON , CE Lamp ON,MIL Lamp ON,ABS
Lamp ON,TCM Lamp ON,SRS Lamp ON,EBD Lamp ON
Fault Effects (On Vehicle)
Default steering assistance, ECM will go into default mode,
ABS degraded functionality, TCM degraded functionality
Lamp Status (If Any)
1) The HVAC outputs (motors and compressor request
signal) should be functional using default data values where
CAN data not available. For Default values refer the CAN
communication matrix (dbc or function net file)].
2) Error frames is observe on CAN bus during the Bus Off
condition.
3) CAN communication is normal.
4) Vehicle communication bus "A" Bus Off DTC is in passive
state in fault memory.
5) The HVAC outputs (motors and compressor request
signal) is respond to the panel request.
Fault Detection Condition
Short circuit between CAN_H -CAN_L, CAN_H -GND, CAN_L-
Vbatt lines. This DTC may also get logged in case of CANH
OR CAN L open circuit.
Normal Operating Condition
ECU communicates properly with all ECUs.
Probable Trouble Area
CAN_H and CAN_L wires
Healing Condition
Removal of the above mentioned shorts/open in the wiring
harness or at ECU pin.