NEXON 2.0 EV DTC Troubleshooting Document for VCU Version: 1.0 draft Date: 31-Jan-2022 Copyright © TATA MOTORS Ltd. This document must not be used in anyway, such as copying and redistributing to third parties, without the consent of author. U1321 - 08: - Lost Communication with Motor control Unit (MCU) module - Bus Signal / Message Failures Overview: ISO Code U1321-08 Customer Symptom Vehicle is not driveable even when D/R/S is selected Fault Effects (On Vehicle) Vehicle is not driveable even when Drive/Reverse/Sport is selected and seen on the cluster. Charging will happen. Lamp Status (If Any) No indication Fault Detection Condition This DTC gets logged when MCU lost CAN communication with VCU Normal Operating Condition Proper CAN communication normal between MCU and VCU Probable Trouble Area LV wiring Harness MCU signal connector/terminals MCU unit Healing Condition Disconnect the MCU and connect it back after VCU sleeps Component Details: Motor Controller Unit controls the Electric motor which draws power from the High voltage battery and converts that electric power into kinetic engrgy which helps to rotate the vehicle. During braking vheicle kinetic energy convert in to eletric energy. Preliminary Checks: 1. Check for proper terminal connection of 12V LV Battery 2. Check LV Battery voltage to be in range (7.5V - 14V) 3. Check LV Supply Connection of MCU for damage (connectors, terminals bending & rusting of pins) 4. Check for loose connection of LV wiring harness between MCU and VCU 5. Check for damage to LV wiring harness connections between MCU and VCU Trouble Shooting: - 1. Check there is no MCU DTC P1306-00 read by the tool. 2. Check for the LV wiring harness connection between VCU and MCU on Powertrain CAN network as per the details given in LV schematic.
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