Transcript Chapter 21

Chapter 21
Instrumentation and Information
Displays
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Instrument Panels
• Dashboard is called the instrument panel
• Consists of gauges, switches, and controls
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Types of Displays
• Analog
– An indicator moves in front of a fixed scale to
indicate a condition
• Digital
– Uses numbers or graphic symbols instead of a
moving needle
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Analog Display
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Digital Display
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Heads-Up Displays
• Projects information
on the windshield in
front of the driver
• Reduces the necessity
to look away from the
road
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duplicated, or posted to a publicly accessible website, in whole or in part.
Types of Digital Displays
• Light-Emitting Diodes (LED)
– Use special diodes that light when energized
• Liquid Crystal Displays (LCD)
– Must have an external light source
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An LCD Display
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Instrument Gauges
• Provide scaled information
• Require voltage regulators and sending
units
• Instrument voltage regulators (IVRs)
stabilize and limit voltage to gauges
• Gauge input is from a sending unit
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Instrument Voltage Regulator
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Air Core Gauge
• Most common type in
modern vehicles
• Needle movement
controlled by a
sending unit
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Quartz Analog Gauge
• Driven by a stepper
motor
• The motor position is
known by the number
of steps commanded
• Commonly used in GM
speedometers
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Magnetic Gauges
• Magnet attracts
ferrous needle
• Armature field
opposes PM
• Attractive or
repulsive forces
move needle
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Instrument Gauges (Cont.)
• Two Coil (Balancing Coil) Gauge
– Uses the interaction of two electromagnets
and the total field effect on an armature to
cause needle movement
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Balancing Coil Gauge
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duplicated, or posted to a publicly accessible website, in whole or in part.
Instrument Gauges (Cont.)
• Bimetallic Gauges
– Are sometimes called thermoelectric gauges
– Use two dissimilar metals to transform the
heating effect of electricity into mechanical
movement
– Some use an instrument voltage regulator (IVR)
to provide a constant voltage to the gauge
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duplicated, or posted to a publicly accessible website, in whole or in part.
Prove-Out Display
• Used to test indicator lights and gauges
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Knowledge Check
• Which type of gauge may be controlled
by a module and a stepper motor?
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duplicated, or posted to a publicly accessible website, in whole or in part.
Basic Information Gauges
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Speedometer
Odometer
Oil pressure gauge
Coolant temperature gauge
Fuel level gauge
Tachometer
Charging gauges
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Speedometer
• Older vehicles used a drive cable
• Vehicles may use a transmission mounted
vehicle speed sensor (VSS)
• Some vehicles use ABS wheel speed sensor
data
• The VSS sends pulses to speedometer head
• VSS information also used by cruise control,
ride control, and engine control modules
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Odometer
• A mechanical odometer may
be driven off speedometer
shaft or by a small motor
• Electronic odometers receive
VSS input
• Mileage data is stored nonvolatile ROM
• Replacement odometers
must represent correct
mileage
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Odometer
• Electronic
odometers receive
VSS input
• Mileage data is
stored non-volatile
ROM
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duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Pressure Gauge
• Typical oil pressure between 45 and 70 psi
• If low pressure or engine off, no current flows
through gauge winding
• A piezoresistive sensor controls current flow
through the gauge
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duplicated, or posted to a publicly accessible website, in whole or in part.
Coolant Temperature Gauge
• Sending unit is usually a
NTC thermistor
• Low coolant
temperature equals
high sender resistance
• High resistance equals
low current flow
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duplicated, or posted to a publicly accessible website, in whole or in part.
Fuel Level Gauge
• Uses a variable
resistor
• Low fuel level
equals low
resistance
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duplicated, or posted to a publicly accessible website, in whole or in part.
Tachometer
• Pulses to the tach usually come from ignition
module or PCM
• Uses a balanced coil gauge
• Increased engine RPM increases the pulses to
the gauge
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duplicated, or posted to a publicly accessible website, in whole or in part.
Charging Gauges
• Most vehicles use a volt gauge or indicator
light
• Older vehicles may have an ammeter
• Indicator lamp will light when charging
system voltage is less than battery voltage
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duplicated, or posted to a publicly accessible website, in whole or in part.
Knowledge Check
• Technician A says when a NTC thermistor is
cold, its resistance is low. Technician B says
when a NTC thermistor is hot, its resistance is
low. Who is correct?
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Indicator and Warning Lights
• Inform the driver of something that is
normally off is now on
• May inform the driver something that is
normally on is now off
• Rear defroster grid indicator lights when on
• ABS and/or traction control light means the
system is off
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Indicator Lights
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Indicator and Warning Lights (Cont.)
• Fasten Seal Belt Indicator
– Illuminates if driver’s seat belt is not buckled
• Tire Pressure Monitor (TPM)
– May light yellow or red depending on pressure
• Brake Warning Light
– Indicates parking brake is engaged, there is low
brake fluid, or a problem with the brake system
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TPMS Warning Lights
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Indicator and Warning Lights (Cont.)
• Antilock Light
– Indicates an ABS fault
• Brake Pad Indicator
– Brake sensors sense thin brake pad lining
• Stop Light Warning Light
– Illuminates if a brake light is inoperative
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Pad Wear Warning Light
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Indicator and Warning Lights (Cont.)
• Traction/Stability Control Lamp
– Indicates a problem in the traction and/or
stability control system
• Check Engine Light
– On late model vehicles this indicates an
emissions system related fault has occurred
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MIL and TC Warning Lights
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Indicator and Warning Lights (Cont.)
• Oil Pressure Light
– May be red or yellow depending on oil
pressure
• Charge Indicator Light
– If charging system voltage is below battery
voltage this light will illuminate
• Check Filler Cap
– Check and tighten fuel filler cap
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duplicated, or posted to a publicly accessible website, in whole or in part.
Indicator and Warning Lights (Cont.)
• Low Fuel Warning
– Indicates fuel level is below one quarter full
• Add Coolant Lamp
– Illuminates if coolant level is low
• Maintenance Reminder
– Mileage triggered light to have vehicle inspected
and serviced
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duplicated, or posted to a publicly accessible website, in whole or in part.
Maintenance Light
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Indicator and Warning Lights (Cont.)
• Transmission Indicator
– Indicates a transmission fault and may place
transmission in limp-in/fail-safe mode
• Drive Indicator
– Used on some 4WD vehicles
• O/D Off Indicator
• Rear Defrost Indicator
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duplicated, or posted to a publicly accessible website, in whole or in part.
Indicator and Warning Lights (Cont.)
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High-Beam Indicator
Left and Right Turn Indicators
Fog Light Indicator
Lamp-out Warning
Cruise Control Light
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Indicator and Warning Lights (Cont.)
• Air Suspension Light
– Illuminates if a fault is present in the air
suspension control system
• Door Ajar Warning
• Washer Fluid Lamp
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duplicated, or posted to a publicly accessible website, in whole or in part.
Sound Warning Devices
• Used to remind drivers of certain vehicle
conditions
– Fasten seat belts
– Air bag operational
– Key left in ignition
– Door ajar
– Lights left on
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duplicated, or posted to a publicly accessible website, in whole or in part.
Park Distance Control (PDC)
• Sensors measure distance from the front
and/or rear of vehicle to an object
• An audible signal increases in frequency as the
vehicle gets closer to the object
• Uses ultrasonic sensors
• May include a visual indicator
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duplicated, or posted to a publicly accessible website, in whole or in part.
PDC Sensors
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Driver Information Centers
• Various gauges, warning lights, and controls
may be grouped together
• May also provide fuel range, economy, and
usage details
• Can show average vehicle speeds, oil life
index, and various engine-operating
parameters
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duplicated, or posted to a publicly accessible website, in whole or in part.
Driver Information Center
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Knowledge Check
• Technician A says a driver warning may be a
yellow or red light on the dash. Technician B
says a driver warning may be an audible
warning. Who is correct?
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duplicated, or posted to a publicly accessible website, in whole or in part.
Hybrid Vehicles
• Honda
– Displays status of
hybrid system, fuel
economy, battery
status, and
charge/assist
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duplicated, or posted to a publicly accessible website, in whole or in part.
Hybrid Vehicles
• Toyota
– Pressure sensitive touch screen
– Energy monitor display
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duplicated, or posted to a publicly accessible website, in whole or in part.
Hybrid Vehicles (Cont.)
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Ready light
Output control warning light
HV battery warning light
Hybrid system warning light
Malfunction indicator light
Discharge warning light
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Ready Light
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General Diagnosis and Testing
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Fuses
Indicator bulbs
Detector switches (indicator systems)
Sender units (gauge systems)
IVR (gauge systems)
Gauges (gauge systems)
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duplicated, or posted to a publicly accessible website, in whole or in part.
Intermittent Problem Causes
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Poor mating of connector halves
Backed out terminals
Wire chafing
Connector body damage
Dirty or corroded terminals
Poor wire-to-terminal connections
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duplicated, or posted to a publicly accessible website, in whole or in part.