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. P302D - 07: - HV Battery Cooling Pump - Mechanical Failures Overview: ISO Code P302D – 07 (Impeller Speed below minimum Speed) Customer Symptom Coolant pump not working Fault Effects (On Vehicle) No coolant circulation in HV battery HV battery over temperature while in crank or charging (subsequent effect) Lamp Status (If Any) If temperature of battery is reached above operable threshold, battery over-heat tell-tale is seen on cluster. Fault Detection Condition As per Bosch base software, Impeller speed of battery cooling pump is below the min speed Normal Operating Condition Low voltage battery voltage between 8V – 14V. Recommended coolant present until prescribed level of coolant tank. Pump operated at requested duty cycle. Probable Trouble Area 1. LV connector 2. Damage/short circuit in wire harness 3. Damage in pump Healing Condition 1. POR (Power-On Reset, i.e. remove the negative terminal of LV battery for 2s) 2. Adjust the Battery cooling pump PWM Duty Cycle as per troubleshooting table Component Details: The BCS pump operates on LV supply. It has the following electrical connections: Switched supply voltage (+ve) UPump, Input signal / diagnosis connection (S = PWM) and Ground (terminal 31, GND, -ve). The pump contains a microcontroller, which decodes the input PWM signal, calculates corresponding set speed of the pump and controls the motor. The pulse-width modulated (PWM) signal is defined by VCU. The operating mode and the set speed of the motor represents frequency (fin) and Duty Cycle (DCin) of the signal.
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