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OSPREY- Application
DTC Troubleshooting Data
Version: 4.0
Date: 10-02-2017
Prepared by: Mithipati Prasad
Checked by: G S Raju / Senthilnathan S
Page: 290 of 654
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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.
P0643: Sensor Reference Voltage “A” Circuit High
Overview:
DTC Description as per ISO standard
Sensor Reference Voltage “A” Circuit
High
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 greater than upper
threshold. This fault gets logged if the Sensor Reference Supply A pins of
EMS ECU are short circuited to Battery
Normal Operating Condition
Diagnostic tool display the Vref status at ignition ON
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
x
Check whether the customer voice / view about the issue is matching with the fault effects mentioned above. If
yes, go ahead with next steps. If not, check for other DTC’s presence.
x
Check whether similar complaints are earlier reported. If yes, perform the preliminary checks with respect to
earlier issue closure.