Vehicle Platform & ECU Name DTC Troubleshooting Data Ver: 1 Date: 23/11/2022 Author: ERC Page 665 of 834 Copyright by TATA MOTORS Ltd. This document must not be used in any w ay, such as copying and redistributing to third parties, w ithout our consent P0687-00: ECM/PCM Power relay Control Circuit/Open - Relay Stuck Overview: DTC Code P0687-00 DTC Description as per ISO standard ECM/PCM Power Relay Control Circuit Stuck 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. Trouble Shooting: Step Checks IF YES IF NO 1. Check whether the EMS ECU is getting power supply and GND Go to step 2 Rectify wiring Harness as per the schematic if found faulty 2. Check whether the Main relay is faulty. Check sensor connections for rust dirt etc., Rectify/Replace if found main relay is faulty and clean the rust or dirt. Go to step 3 3. Are there any pins damaged at EMS ECU Connector Replace the connector or wiring harness Go to step 4
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