TIAGO/TIGOR AMT Gasoline DTC Troubleshooting Guide Version: 4.0 Date: 18-04-2017 Author: Sathi/Anupama Page: 137 of 427 Copyright © TATA MOTORS Ltd. This document must not be used in any way, such as copying and redistributing to third parties, without the consent of author. 42. P0703 -02: Brake switch input circuit – Signal not valid Overview: ISO Code P0703-02 Customer Symptom Transmission Fault Lamp ON Creeping inactive, Fault Effects (On Vehicle) Creeping inactive, Lamp Status (If Any) Transmission Fault Lamp ON Fault Detection Condition This fault gets detected after Ignition On if EMS signals the TCU that brake pedal information on CAN is invalid. Normal Operating Condition EMS signals the TCU that brake pedal information on CAN is valid Probable Trouble Area Wiring Harness Connections / EMS / TCU Healing Condition 200 milliseconds after valid sensor signal Component Details: Brake switch is connected to the EMS. Brake pedal position signal is transmitted by EMS via CAN bus to the TCU. Preliminary Checks: 1) Loose/ Damaged Brake pedal switch Connections. 2) Check for damage or back out of pins at EMS connector and TCU connector. 3) Check correct fitment of ground cable connections on vehicle chassis. Trouble Shooting:- Step Checks IF YES IF NO 1. Is there any rust/oxidation observed on EMS or TCU connectors? Clean the Rust or repair or replace Go to Step 2 2 Diagnose the Brake pedal input to EMS (Refer EMS service manual), is there a problem with Brake pedal switch or switch to EMS connection? Ensure correct connection of brake pedal input to EMS as per EMS service manual. Go to step 3 3 Is TCU power connections on TCU connector pins 5, 1, 3? Specifically check Ignition supply toggling with key on/off. Go to Step 4 Check and rectify harness power connections. 4 Connect the EMS diagnostic tool and check the value of brake pedal position with pressed and unpressed pedal, are correct values observed? Follow the steps again for reconfirmation Recheck the above steps DTC’s confirmation:- After rectification, clear all DTC’s and ensure the following points by referring TCU parameters using TML diagnostic tool before handing over to customer. After key and engine ON with TML TCU diagnostic tool connected, monitor the brake press status and confirm that it changes from about 0 unpressed to 1 when pressed fully. Drive the vehicle through all gears in both Automatic and Manual modes. Ensure no DTC is active and Transmission Fault Lamp is OFF. Circuit Schematic Diagram:
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