1139 / 5157
Nexon Gasoline – EMS ECU Bosch
DTC Troubleshooting Manual
Version: 0.1
Date: 26-08-2017
Prepared By: Sunu S Babu/Yogesh Jadhav
Checked By: Yeshwant Jadhav
Approved By: Satish Kumar
Document Part No: 2921 02 224 A1736
Page: 1135 of 1203
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.
P302F-1: Detection of an Early Opening Main Relay– General Electrical Failure
Overview:
ISO Code
P302F-1
Customer Symptom
1. ECU will be switched off immediately without completing postdrive(loss of
data may occur)
2..In long term ECU can be damaged
Fault Effects (On Vehicle)
1. ECU will be switched off immediately without completing postdrive(loss of
data may occur)
2..In long term ECU can be damaged
Lamp Status (If Any)
No Lamp Indication
Fault Detection Condition
This fault gets logged if the Main relay control pin of EMS ECU is not getting
supply from battery.
Normal Operating Condition
Healthy wiring harness connections between Main Relay and EMS ECU
Probable Trouble Area
Wiring Harness Connections, Main Relay Pin Connection, Main Relay
Condition, Faulty Fuse, Low Battery
Healing Condition
Ignition On or Engine After Run & after 1 drive cycles of fault rectification.
Fault permanent Deletion
1. Clear DTC Command form Scan tool
2. Stack Over Flow.
3. 40 warm up cycles.
4. ECU Flashing.
5. ECU Power-Fail
Component Details:
Majority of the EMS components gets the power supply after the Main Relay is switched on by EMS ECU.
Preliminary Checks:
1. Check Relay Control Pin
2. Check Supply line from Battery to ECU also Battery to Main Relay
3. Check Main Relay is in Good Condition
4. Check whether Fuse is faulty.
5. Check the Battery condtion.