Download Understanding Computer Control Systems

Electrical 2
Understanding Computer Control Systems
 Processing system
 Input
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Sensors
Switches
Data bus CAN or OBD
 Processing
 Electronic Control Module
(ECM)
 Parameters, setting and
programming
 Output
 Solenoids
 Data bus CAN or OBD
 MIL lights
 Motors or Actuators
Understanding Computer Control Systems
 Switches
 Key
 Cruise
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On off
Set resume
 Retarder
 On off
 Level
 Brake
 Service (some systems will
utilize 2)
 Park
 Switches
 Interlock
 PTO
 Door
 Throtle
 Idle Validation
Switch (IVS)
Understanding Computer Control Systems
 Temperature
 Thermistor
 Thermocouple
 Negative Temperature
Coefficient (NTC)
 Positive Temperature
Coefficient (PTC)
 Two wire

Passive sensor
 Three wire
 Active sensor
 Used for
 Water temp
 Oil temp
 Air temp
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EGR
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Ambiant
Manifold
Pre cooler
Post cooler
Fuel temp
Cabin temp
Understanding Computer Control Systems
 Pressure (piezo)
 Piezoresistive
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 Used for
 Oil pressure
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Standard on Detroit,
Caterpillar, and VolvoMack
 Piezoelectric
 Standard on Cummins and
some heavy equipment
 YouTube on Piezoelectric
 Mechanical
 Older electrical gauges
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Fuel pressure
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Engine lube
HEUI action
Hydraulic
Primary
Secondary
Air Pressure
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
Manifold
Atmospheric
Understanding Computer Control Systems
 Speed and position
 Permanent magnet
 Hall effect
 Potentiometer
 Used for
 Wheel speed
 Crankshaft
 Camshaft
 Fuel pump
 Actuators
 Vehicle speed
 Throttle
 Accessories
Understanding Computer Control Systems
 Databus
 Automotive
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
OBD I
 Vehicle manufacture sets standard
OBD II
 Current
 Heavy duty
 CAN
 J1587 or J1787
 J1939 or J1922
 Proprietary link
J1587
J1939
Connectors
Understanding Computer Control Systems
 Processor
 Electronic Control
Module (ECM)
 Programming and
Parameters
 Settings
 ECM used on
 SRS
 ABS/ATC
 Engine
 Transmission
 Dashboards
 Power trains
Understanding Computer Control Systems
 Solenoids
 Actuators for
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Injection
Retarder oil flow
Pneumatic fans
Hydraulics
Starting aids
EGR
Intake Valve Actuators or
Variable Valve Actuators
Understanding Computer Control Systems
 Malfunction Indicator
Lamp
 MIL
 Shutdown Engine Lamp
 SEL
 Check Engine Lamp
 CEL
 Antilock Brakes
 ABS
 Automatic traction Control
 ATC
 Transmission
 Automated
 Automatic
Understanding Computer Control Systems
 Motors/Actuators
 Electronic over
Mechanical pumps
 Emissions

EGR
 Variable Nozzle Turbo
 VNT
 Variable Geometry
Turbo

VGT
Understanding Computer Control Systems
 Diagnostic Trouble Codes
 DTC
 Flash codes or proprietary
codes
 SAE codes
 Message Identifier
 MID
 Parameter Identifier

PID
 System Identifier
 SID
 Component Identifier
 CID
 Utilizes only one of the
following PID, SID, or CID
 Failure mode Identifier
 Active
 Currently occurring
 Can not be cleared
 Historic
 Is a record of a code
 Can normally be cleared
some require a password
Understanding Computer Control Systems
 Examples of Common SAE J1708
Message Identification - MID
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MID 128 Engine
MID 130 Transmission
MID 136 Brakes, Power Unit - ABS
MID 140 Instrument Cluster
MID 144 Cruise Control / Vehicle
Control Unit
MID 146 Cab Climate Control
MID 150 Suspenstion, Power Unit
MID 166 Tires, Power Unit
MID 177 Particulate Trap System
MID 181 Communication Unit,
Satellite
MID 200 Auxillary Cab Climate
Control MID 216 Light Control
Administrator Unit
MID 232 Safety Restraint System
MID 249 Body Controller
 Examples of Common SAE 1708
Parameter Identification - PID
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PID 8 Brake system air pressure Low
warning switch statuts
PID 12 Brake Stroke Status
PID 27 Percent Exhaust Gas
Recirculation Valve #1 Postision
PID 51 Throttle Postion PID 80
Washer Fluid Level
PID 81 Particulate Trap Inlet
Pressure
PID 84 Road Speed
PID 91 Percent Accelerator Pedal
Position
PID 94 Fuel Delivery Pressure
PID 97 Water In Fuel Indicator
PID 98 Engine Oil Level f
Understanding Computer Control Systems
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Examples of Common SAE J1708 Subsystem
Identification - SID
SID 213 PLC Data Link
SID 231 SAE J1939 Data Link
SID 232 5 Volts DC Supply
SID 250 SAE J1708/J1587 Data Link
SID 251 Power Supply
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Examples of Common SAE J1708 Failure
Mode Identifiers - FMI
FMI 0 Data Valid but above normal
operational range
FMI 1 Data Valid but below normal
operational range
FMI 2 Data Erratic
FMI 3 Voltage above normal - Shorted High
FMI 4 Voltage below normal - Shorted Low
FMI 5 Current below normal - Open Circuit
FMI 6 Current above normal - Grounded
Circuit
FMI 7 Mechanical System Fault
FMI 8 Abnormal Frequency
FMI 9 Abnormal Update Rate
FMI 10 Abnormal Rate of Change
FMI 11 Failure Mode not Identified
FMI 12 Bad Device
FMI 13 Out of Calibration
FMI 14 Special Instructions
Understanding Computer Control Systems
 Reading codes
 Flash Codes

Utilizes equipment



Switches
Lights
Different procedure for
different equipment


Dedicated switches
Other switches
 Diagnostic Data Reader
 OEM specific
 Generic
 Personal computer
 Generic
 OEM
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
Insite
Electronic Technician
Detroit Diagnostic Data
Link
Understanding Computer Control Systems
 Strategy Based Diagnostics
(SBD)
 Verify customer complaint
 Quick check vehicle
 Check DTC and history
 Check TSB’s
 Follow the service manual
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
troubleshooting
Analyze and record DTCs
Clear codes
Recheck DTCs
Determine course of
action
Understanding Computer Control Systems
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Understanding Computer Control Systems
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