2. Introduction
Participant Name
Dealership Name
Location
Experience in Tata Motors (In years & months)
Specialization in which Models / Aggregates
Hobbies
What Bonds you with TATA MOTORS
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3. Program Objectives
At the end of this module the participants will be able to:
Understand the basic electrical systems in a Bus
Trace the starting circuit of a bus
Understand the basics of Multiplexing
Identify and locate the fuse box and fuses in a bus
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4. Program Agenda
Introduction
Bus electrical system
Starting circuit
Introduction to Multiplexing
Fuse box location and fuses
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6. Introduction
A circuit includes the following basic parts:
– Power Source, e.g. Battery
– Conductors, e.g. Wiring
– Load, e.g. Head Lamp
– Controls, e.g. Switch
In addition to these there are other devices used to protect these circuits. These are:
– Relays
– Fuses
– Circuit Breakers
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7. Basic Components of Body Electrical System
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Head Lamp Tail Lamp Combination Switch
Relays Switches
15. Introduction to Multiplexing
What is Multiplexing ?
Multiplexing is a concept of using just two / three (CAN) wires to perform the task of many
wires.
The multiplexing wiring system allows multiple electronic messages to travel back and forth
through the same data link wire.
The multiplexing wiring system’s electronic control modules remotely send information back
and forth, monitoring vehicle components and interpreting messages transmitted through
the wires.
Multiplexing integrates all the vehicle ECUs into a network where coded digital information is
transmitted through a single data cable.
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16. Benefits of Multiplexing
Improved reliability
The multiplexing wiring system
– Reduces the number of wires by over 40% there by reducing possible failure points
– Improves vehicles integration process by reducing the amount of cabling
– Complex knobs & switches can be replaced by cheaper touch keys
Easier to modify
It is easier to add or remove certain additional features from the vehicle by just reprograming
the process without actually changing the hardware. So the vehicle spends less time in the
shop and more time on the road.
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17. Benefits of Multiplexing..
Improved Diagnostic Capabilities
Software can be easily programmed to handle many diagnostic features from the detection of
blown light bulbs to the failure of emission control systems in an automobile
A major highlight of a multiplex system is ease of fault finding
Fault may be:
– An open circuit
– A short circuit
– Communication error
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18. Traditional Wiring Vs Multiplexed Wiring
Traditional wiring harness
Fuses on all lines
Single power lines
No diagnosis
Multiplexed wiring harness
Main fuse only
Main power line
Local power distribution
Diagnosis possible
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switches fuses
+
Battery
Load
fuse
Input/Output
+
MUX
CAN
Datenbus
Power
MUX
Input/Output
fuses
Battery
19. On Board Diagnostics with Multiplexing System
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Master
Switch light on
Slave
Software Handshake
Mail from Master to Slave
20. On Board Diagnostics with Multiplexing System
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Master
Okay,
well done
Slave
Light is on
Software Handshake
Mail from Slave to Master
21. On Board Diagnostics with Multiplexing System
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Master
Oh,
there is a problem
with my light
Light
not
working
• . . .
• Store for diagnosis
• Report to Driver
Slave
Software Handshake
Error with light
Mail from Slave to Master
25. Now we will trace the basic starting circuit of a multiplexed bus
Please pay close attention to the integration of the multiplexing
system in the starting circuit
Instructions:
Trace the current flow through different components of the starting
circuit
Trace the current flow through the different components of the
charging circuit
Trace the current flow through the ignition switch
Understand the function of particular components in the circuit
Practical
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Circuit Tracing
Duration 120 Mins Note:
1) This exercise is completely trainer led
2) Trainer is supposed to guide the trainees in
tracing the starting and charging circuits
