NEXON DIAGNOSTIC MANUAL

OSPREY- Application

DTC Troubleshooting Data

Version: 4.0

Date: 10-02-2017

Prepared by: Mithipati Prasad

Checked by: G S Raju / Senthilnathan S

Page: 284 of 654

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.

P0642: Sensor Reference Voltage “A” Circuit Low

Overview:

DTC Description as per ISO standard

Sensor Reference Voltage “A” Circuit Low

ECU Pin Number

75, 37, 77

Customer Symptom

Reduced torque mode gets activated.

Engine may not start; Engine vibrates if this fault gets detected in Engine

running condition.

Fuel Consumption Increases

Fault Effects (On Vehicle)

Disable discharge on injector 3

Temporized engine stop

Disable RPC trim fault detection

Ensures the rail pressure demand is inferior to a maximum rail

pressure demand.

Pressure is controlled by the high pressure valve open loop, Rail pressure

control is in HPV Only mode, TDC measurement is not valid, tooth one is

used as recovery.

Disables discharge on injector 1

Disables cylinder balancing strategy

Disables the RPC Build measurement

Activation of the reduced torque 3

Disable the Rail Pressure Control Fault Detection

Disable high pressure leak detection strategy

Disable discharge on injector 2

Disable pilot and post injections

Limp home mode activation

Lamp Status (If Any)

CE lamp is on

Fault Detection Condition

This DTC gets logged if the sensor supply Voltage 1 is less than lower

threshold.

Normal Operating Condition

Diagnostic tool displays the Vref status at ignition ON. Healthy Supply

Voltage to Sensors (5 Volts).

Probable Trouble Area

ECU Main relay, ECU, Wiring harness

Healing Condition

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

Component Details:

EMS ECU has two Internal 5 Volts power supplies. Power Supply 1 will provide input voltage to a group of sensors

–

A. and Power Supply 2 will give input voltage to another group of Sensors-B.

Preliminary Checks

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

yes, go ahead wi

th next steps. If not, check for other DTC’s presence.

Check whether similar complaints are earlier reported. If yes, perform the preliminary checks with respect to

earlier issue closure.