Intake Manifold Temperature Sensor Engine Coolant Temperature Sensor
System Components - Wiring Harness • Engine harness connects engine mounted sensors and actuators to ECM
• Traditionally wiring and connectors is highest cause of reliability problems
• Incorporates robust sealed connectors • Connectors are designed for long service life • Cable insulation is capable of withstanding temperature and fluid exposure
• Outer covering provides protection from damage due to vibration, heat and general abuse
• Harness routing and connector ‘keying’ is used to prevent incorrect connection of components
Electronically Controlled Fuel Systems Caterpillar 3000 Series z VP30 Pump
Bosch VP30 Fuel Injection Pump Pump ECU Fuel Temperature Sensor
Basic System - Interactions CONTROL INPUTS Sensors: Pressure,Temperature, Speed/Timing Cables/Connectors
Switches/Pushbuttons Power Supply 12 v or 24 v
INPUTS
OUTPUTS
5/8 volts sensor supplies and operation
Computer Hardware + Software
Indicator lights Actuators Cables/Connectors
ECM
Relays
OUTPUTS CAT DATA LINK
SERVICE TOOL
C.A.N. DATA LINK
PUMP TO ECM/FLASH
System Components ECM Hardware INPUTS
COMMUNICATIONS LINKS
Digital
Digital Analogue voltage
OUTPUTS
PROCESSOR
PWM MEMORY
PWM
Electronic Control Module: Essential Facts • High reliability • External connectors most vulnerable • No serviceable parts • Never replace without full diagnostic test • All warranty returns checked • No fault warranty returns - no warranty credit • ECM is the LAST component you should suspect being faulty
Engine Speed Controls Sensor Types
System Components – Speed Controls Throttle Position Sensors/Controls
• Cat Machines
- Pulse Width Modulation (PWM) - Set Speed Switches
• Industrial Engine, pedal
position/operator demand
Voltage o/p
- Pulse Width Modulation (PWM) - Contacting, resistive track potentiometer type devices. • Provide linear voltage output (0.5v to 4.5v) Low Idle
High Idle
• Should have idle validation switches on mobile applications for failure detection.
PWM Throttle Position Sensor Three wires:
• Ground • +8 Volt supply • PWM Output
System Components Throttle Position Sensors • Pulse Width Modulation (PWM) is an output that is defined by its duty cycle.
• The duty cycle is the relation between the time on to the time off.
• More consistent than a linear sensor type. • Above 90% and below 10% implies there is an error present.
IDLE(0.9volts)
FULL THROTTLE (4.6volts)
System Components • Temperature Sensors: Passive type - Commonly known as magnetic pick-ups - Produce a sinusoidal voltage signal. Signal conditioning is required in the ECM
• Pressure Sensors: Active type: - Hall effect - Produce a ‘conditioned’ square wave signal - More costly than passive sensors
Engine Mounted Sensors
On Engine Sensor Wiring J201 P201
ENGINE OIL PRESSURE SENSOR
SENSOR VREF +5V
A
ENGINE OIL PRESSURE
C
SENSOR COMMON
B
P1 J1
J200 P200
INTAKE MANIFOLD PRESSURE SENSOR
ENGINE COOLANT TEMPERATURE SENSOR
SENSOR VREF +5V
A
INTAKE MANIFOLD PRESSURE
C
SENSOR COMMON
B
ECM
L730
26
SENSOR VREF +5 VOLTS
994 X731
24 14
ENGINE OIL PRESSURE
995
15
ENGINE COOLANT TEMPERATURE
C967 L731
32 34
SENSOR COMMON O VOLTS
INTAKE MANIFOLD PRESSURE
J100 P100 ENGINE COOLANT TEMPERATURE
1
SENSOR COMMON
2
J103 P103
INTAKE MANIFOLD TEMPERATURE SENSOR
INTAKE MANIFOLD AIR TEMPERATURE SENSOR COMMON
1 2
J401 P401
SPEED AND TIMING SENSOR NO.1
CRANKSHAFT POSITION +
2
CRANKSHAFT POSITION -
1
INTAKE MANIFOLD AIR TEMP
E966
E965
41 49 33
CRANKSHAFT POSITION +
CRANKSHAFT POSITION CRANKSHAFT POSITION SCREEN
System Components Temperature Sensors
• Thermistors: - Semiconductor sensing devices - Resistance varies with temperature - Negative Temperature Coefficient (NTC) most common i.e. As temperature increases its resistance decreases - 40 to 300ºF range - Passive sensor ⇒ lower cost
Temperature Sensors • Thermistor Ground Pin No 2
Signal Pin No 1
Temperature Sensors • 3054E/3056E Applications - Intake Manifold Temperature Sensor - Engine Coolant Temperature Sensor
System Components Temperature Sensors Volts
Ohms (Resistance)
25,000
Volts Ohms
5.0
5,000 0.5 Increasing Temperature
ECM
Temperature (Passive) Sensor Operation
+5 VOLTS REFERENCE SUPPLY
R1
MIC R
ANALOGUE TO DIGITAL CONVERTER
R2 0 VOLTS TEMPERATURE SENSOR
OP RO CE SS OR
System Components Pressure Sensors Pressure: • Active Sensors (i.e. with built in conditioning electronics) provide analogue voltage output with linear and temperature compensation.
• Various working ranges to suit measured parameter e.g. - 12 to +17 psi (abs) - Atmospheric pressure 0 to 70 psi (abs) - Intake manifold pressure 0 to 115 psi (abs) - Engine oil pressure abs = absolute (pressure)
System Components Other Sensors (Industrial): • Coolant Level Sensor
System Components Speed/Timing Sensors • Applications: - Determine rotational speed and rotational position • Primary - Crankshaft speed and position • Secondary - Camshaft/fuel pump speed and position
Primary Speed/Timing Sensor
Speed/Timing Sensor • The 3000 series engines use a 36-1 tooth ring. i.e. the timing ring has space for 36 teeth, and one is missing. The missing tooth allows the ECM to determine the timing of the engine. The wheel is dowelled to index it to the crankshaft.
40 Degrees - 6 Cylinder
Top Dead Center
70 Degrees 4 CYL
Rotation
System Components - Speed Sensors Passive Speed Sensors Iron Core
Magnet Coil Flux Lines
Pole Piece Direction of motion Teeth
Crankshaft
Secondary Speed/Timing Sensor Installation
ECM (6 cylinder Engine)
Speed/Timing Sensor
System Components – Speed/Timing Sensors Speed/Timing Sensors – failure Modes Primary sensor Defaults to Secondary Engine runs in “limp home” mode (max 1200 rpm) Engine will start and run with a failed sensor
Secondary sensor Engine stops and will not start
Teeth
System Components Output Devices • Typically include: - Relays - Lamps - Gauges (PWM)
System Components - Actuators Electronically Controlled Fuel Pump
• “Intelligent” rotary pump e.g. Bosch VP30 - Local pump mounted ECU controls pump solenoids to achieve desired fuel delivery and timing. - Main ECM communicates desired timing and fuelling via CAN communication link
Electronic Service Tools • Communication Adapter (CA II) (CA I can be used if necessary)
• CAT ET (Electronic Technician)
Electronic Service Tools CAT ET Service Tool:
• PC based, multi function - Status Screens - Diagnostics - Flash Programming
Electronic Technician CAT ET z
The first element of STW (Service Technician Workbench)
z
Common for all future Caterpillar electronic engines
z
Hardware and software required
z
Annual subscription
z
Not compatible with Perkins 1100 Series engines
ET Service Tool Communication Adapter Group
CAT ET (Electronic Technician) Functionality includes: z
Controller Area Network (CAN) z (Two CAN data links on 3054E/56E)
Example of CAN wiring HAND HELD SERVICE TOOL
NODE DATA BUS
Address 249
Ohm TERMINATING RESISTOR
120 Ohm TERMINATING RESISTOR
MACHINE INTERFACE CONNECTOR 52 61
INSTRUMENT PANEL Address 23
GEARBOX ECM
NODE
Address 3
The CAN shield not connected to ECM
ENGINE ECM Address 0
Controller Area Networks (CAN) Introduction:
• CAN is the communication network between intelligent electronic devices used on an application.
• Ground based equipment use a version of CAN that conforms to an international standard known as J1939
• Application control, monitoring and diagnostics is possible using J1939.
Controller Area Networks (CAN) Advantages:
• Uses less wiring, lower weight, lower cost, etc. • Uses fewer connections, more reliable. • Easier to install. • Improved quality of signal. • Transmission of huge amounts of data.
3054E/3056E CAN Data Link Usage CAN J1939
• Flash Programming
CAN Proprietary Data Link
• ECM to Pump ECU communication
CAN - J1939 Examples of CAN Data link Uses: • ECM to Engine Fuel Pump: Transmits engine power requirements to pump ECU
• Transmission to Engine: Tells the engine what gear is currently selected
• Engine to Machine: Broadcasting of engine parameters (e.g. engine speed, oil pressure, coolant temp.)
