Vehicle Platform & ECU Name DTC Troubleshooting Data Ver: 1.0 Date: 30/11/2019 Author: ERC Page 441 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 P0504-00: Brake switch fault Overview: Description as per ISO standard Brake Switch “A” Circuit Customer Symptom Stop lamp function may get affected. ECU PIN No B46, B48 Fault Effects (On Vehicle) Stop lamp function may get affected. Lamp Status (If Any) CE Lamp ON Fault Detection Condition This fault gets detected if EMS doesn’t find coherence between the Main Brake switch input and Redundant Brake switch input for a calibratable time. Normal Operating Condition EMS ECU finds coherence between Brake Switch inputs Probable Trouble Area Wiring harness Connections between Brake Switches and EMS ECU, Improper Brake Switch Setting, Brake switches, EMS ECU Component Details: For safety reasons, Brake pedal is equipped with two Switches. These switches transition their states when the brake pedal is pressed. EMS ecu uses the brake press information in its control strategies like Torque demand calculation, Gear Shift indication, Accelerator pedal stuck detection, vehicle start function when clutch sensor fails etc., 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 Brake Light Switch / Brake safety Switch are either stuck open or closed. Check, if the Brake lights are on even when no brake pedal is pressed. Loose/ Damaged Connections between Brake Switch connector and EMS ECU. Check for back out / damage of pins at ECU connector. Check for back out / damage of pins at Brake switch connector. Check for any physical damage of EMS ecu / Brake switches connectors.
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