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: 368 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.

P0194-84: Fuel Rail Pressure Sensor "A" Circuit Intermittent/Erratic : Negative offset of the rail pressure sensor

exceeded

Overview:

DTC Description (User Friendly)

Fuel Rail Pressure Sensor "A" Circuit Intermittent/Erratic:

Negative offset of the rail pressure sensor exceeded.

ECU Pin Number

A042 – 5V supply from EMS to rail pressure sensor

A062 – Input analog signal from rail pressure sensor to EMS

A063 – Gnd supply from EMS to rail pressure sensor

Customer Symptom

Once the engine is started and running - Engine vibrates and

makes noise, Power loss. Engine will stop after delay.

Fault Effects (On Vehicle)

Group Fault for Engine stop after delay gets activated.

Group Fault for disabling pilot injection will get activated

Rail Valve Discharge will be disabled, EGR will be disabled,

Allows the IMV to operate without trim values, Deactivates the

Leak Detection test, Forces the IMV to open fully,

Limits the System Pressure demand to calibratable pressure

in bar, Deactivates the Rail pressure sensing/ Measurement,

Rail Pressure Build measurement is deactivated, Disables the

Rail pressure control fault detection, Limp Home Mode

activated.

Lamp Status (If Any)

MIL Lamp is ON1 and CEL is OFF.

Fault Detection Condition (Root cause)

If the raw value of the rail pressure remains below the

threshold 424 volt for the number of monitoring cycles 3

during startup or below the threshold 424 volt for the number

of monitoring cycles 10 during afterrun, the offset is too great

in the negative direction and the rail pressure sensor will be

classified as defective.

Fault detection time:

During startup 3;

In afterrun 10.

Duration of healing time:

During startup 3;

In afterrun 10

Normal Operating Condition

No faults related to Rail Pressure circuit.

Probable Trouble Area

Rail pressure sensor, ECU, Wiring harness.

Healing Condition

Clear the errors, Ignition OFF to ON, engine idle, fly-up and

specially vehicle running in different speed condition

Component Details:

Rail pressure sensor is a piezoelectric type one, which is used to measure the fuel pressure inside the Rail. It provides the

pressure in terms of voltage to the ECU. This rail possesses an under pressure supply of diesel fuel which is ready to be

used by the injectors. The drop of pressure in the rail is immediately signaled by the sensor to the engine control unit. This

is followed by the restoration of pressure in the pump. It is the engine control unit that controls the fuel supply of the rail

from a pump possessing very high pressure. This is done by using a valve for controlling the pressure of fuel.

Preliminary Checks: