HARRIER BOOK 2

Q501 4 Cylinder MT Application

DTC Troubleshooting Data

Version: 0.1

Date: 21-Sep-2018

Prepared By: Mithi Prasad, Sarang Kulkarni, Manish Gupta

Checked By: Yogesh Jadhav

Approved By: Satish Kumar P

Page: 428 of 1052

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.

P1279-72: Relay Stuck Open Plausibility error

Overview:

DTC Description (User Friendly)

Relay Stuck Open Plausibility error

ECU Pin Number

K072 – EMS Output to starter relay high side

K055 – EMS Output to starter relay low side

K085 – Input signal to EMS ECU from VSensing sensor.

Customer Symptom

MIL OFF, CEL ON

Fault Effects (On Vehicle)

Lamp Status (If Any)

CEL ON. CEL Turns Off as and when fault condition is not

present / healed.

Fault Detection Condition (Root cause)

The error is checked only if the following conditions are

satisfied.

1. Starter relay activation command is present for a minimum

period of 200ms.

2. when battery voltage is above certain voltage 8000 volt.

3. Engine speed is detected i.e > 0.

4. The engine running condition is used as a condition for

evaluation the DTC in case of no feedback circuitry for the

starter.

Normal Operating Condition

Proper wire harness connection between starter relay and

EMS ECU.

Probable Trouble Area

Wire harness connection between starter relay and EMS

ECU.

Healing Condition

Rectify the error Clear through diagnostic tool.

Ignition OFF & ON

Component Details:

A starter

relay

is the part of an

automobile

which switches a large

electric current t

o the

starter motor,

in response to a

small control current, and which in turn sets the engine in motion.

Preliminary Checks:

1. Check whether the customer voice / view about the issue is matching with the fault effects mentioned in above

Table. If yes, go ahead with next steps. If not, check for other DTC’s presence.

2. Check whether other customers report similar complaints earlier. If yes, perform the preliminary checks with

respect to earlier issue closure.

3. Check for wire harness connection between EMS and starter relay.

4. Check for any back out of pins at EMS ECU connector.

5. Check for any damage of pins at EMS ECU connector.

Trouble Shooting: