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. Electric coolant pump and its pin details Pump can recognize dry run if the impeller speed is below minimum speed nMin. After a recognized event “impeller speed below minimum speed”, the pump speed is set to zero. After a certain time, a restart attempt is performed. Restart attempts will take place after certain pause times, if the event “impeller speed below minimum speed” is permanently detected and a diagnosis will be sent Figure 1 Pause time between the restart attempts Preliminary Checks: 1. Check for design intended LV Battery. Voltage should be in range of 8V – 14V 2. Check if coolant is present until prescribed level of coolant tank. 3. Check for any leak in coolant lines. 4. Check for the pump connection with VCU using LV schematic Troubleshooting: Step Description Check point If Yes If No 1 Check whether the vehicle is in Ignition State, vehicle speed is 0 and LV battery voltage is >11 V. Using TML Diagnostic Service Tool give command to operate actuator: ‘Battery cooling pump PWM Duty cycle’ (DID No: 3437- Confirm whether positive response is received. Go to step 2 Ensure the preconditions to be OK (Vehicle is in Ignition mode; vehicle speed is 0 and LV battery Voltage is >11 V) Check for the negative response
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