Vehicle Platform & ECU Name DTC Troubleshooting Data Ver: 1.0 Date: 30/11/2019 Author: ERC Page 528 of 610 Copyright by TATA MOTORS Ltd. This document must not be used in any way, such as copying and redistributing to third parties, without our consent P0687-00: ECM/PCM Power relay Control Circuit/Open - Relay Stuck Open Overview: DTC Description as per ISO standard ECM/PCM Power Relay Control Circuit Stuck/Open ECU Pin Number 3,5,6,41,64 & 87 Customer Symptom Engine will not start Fault Effects (On Vehicle) Cannot communicate with the ECU. Lamp Status (If Any) CE lamp ON Fault Detection Condition This DTC gets logged due to EMS power supply cutoff due to drop out of main power relay..or relay switch stuck(PIN 87 and PIN 30 of main relay) Normal Operating Condition Diagnostic tool displays the Battery supply status at ignition ON. Probable Trouble Area ECU Main relay, ECU, Wiring harness Healing Condition Clear the errors, Ignition OFF to ON, engine idle & fly-up condition Component Details: EMS ecu gets wake up with Ignition switch input and energizes the main power relay coil to get the power supply to EMS. Preliminary Checks Check whether the customer voice / view about the issue is matching with the fault effects mentioned above. If yes, go ahead with next steps. If not, check for other DTC’s presence. Check whether similar complaints are earlier reported. If yes, perform the preliminary checks with respect to earlier issue closure. Check whether the EMS ECU is getting power supply and GND. Rectify wiring Harness as per the schematic if found faulty. Check whether the Fuse of EMS main relay supply is blown Off. If so replace the fuse. Check whether the Main relay is faulty / contacts stuck open. Rectify/Replace if found main relay is faulty. Check for damage / back out of pins at EMS Connector. If found rectify / replace.
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