TATA BSVI Gasoline_Bifuel Program – EMS ECU Bosch DTC Troubleshooting Service Manual Version: 2.6 Date: 5-10-2023 Prepared By: Pradip Shimpi Checked By: Yeshwant Jadhav Approved By: Sanjeev M. Document Part No: 2921 02 xxx xxxx Page: 1656 of 1720 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. P0703-14: Brake switch open error – Open or Short to Ground Overview: ISO Code P0703-14 Customer Symptom In AMT vehicle, vehicle will not start. Fault Effects (On Vehicle) 1. vehicle may not start in case of AMT vehicle. 3. Brake lamp may not turn ON pressing the brake. 4. Brake related fuse may be blown (Brake lamp fuse or Ignition brake fuse) Lamp Status (If Any) SIL (Service lamp) ON in 1st drive cycle Fault Detection Condition Brake connector open or Brake pins at EMS ECU are open or shorted and inputs received from brake switch to EMS ECU are not correct. Normal Operating Condition No fault present and inputs from brake switch to EMS are correct. Probable Trouble Area Brake Connector, Brake switch, brake Related WH, EMS ECU Healing Condition CEL Lamp will turn OFF after 1 driving cycle if fault is cleared. Fault Permanent deletion 1. Clear DTC Command from Scan tool 2. Stack Over Flow 3. 40 warm up cycles 4. ECU Flashing 5. ECU Power-Fail Component Details: Brake switch ia s 4 pole digital switch which is interfaced to EMS ECU. Brake main switch (first input with half press) and brake redundant input (second input with full brake press condition) are received by EMS ecu correctly in norma working condition. EMS publishes CAN signal as brake pressed when brake is pressed fully. Brake input is very critical input with respect to vehicle’s performance and safety. To start an AMT, it is required to completely press the brake pedal along with crank input. Preliminary Checks: 1) Loose/ Damaged Connections between Sensors/actuators and EMS ECU. 2) Check for back out of pins at both barke sensor and ECU connector. 3) Check for damage of pins at both Brake switch connector and ECU connector. 4) Check the continuity from Sensors/actuators connector pins to the ECU pins. 5) Check if brake lamp or ignition brake fuses are blown away? Trouble Shooting:- Step Checks IF YES IF NO 1 Visual inspection – check for open brake connector / loose connection / WH damage / back out of pins / fuse blow at brake switch connector side or EMS ECU side Rectify the problem. And press brake fully and release, Go to Step 2 2 Check if brake switch pins at EMS ECU (135 and 147) are open circuited or Short circuited to GND or battery? Rectify the problem. And press brake fully and release, Go to Step 3 3 Replace the brake switch sensor and brake connector? Rectify the problem. And press brake fully and release, Go to Step 4 4 Fault Still Persists? Replace the EMS ECU. And press brake fully and release, Clear DTC
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