3500B Engines Electronic Circuits Caterpillar


Electronic Circuits
`
3500B Engines [RENR1304]
ELECTRICAL AND STARTING SYSTEM
ELECTRONICS GP-ENGINE
1.1. Electronic Control Module (ECM)
2.1. Engine Speed/Timing Input Circuit
3.1. Coolant Temperature Input Circuit
4.1. Hydraulic Oil Temperature Input Circuit
5.1. Throttle Switch Input Circuit
6.1. Automatic Engine Speed Control (AESC)
7.1. User Defined Shutdown Circuit
8.1. Aftercooler Temperature Input Circuit
9.1. Gear Box Temperature Input Circuit
10.1. Demand Control Fan System Output Circuit
11.1. Injector Output Circuits
12.1. Atmospheric Pressure Input Circuit
13.1. Turbocharger Inlet Pressure Circuit
14.1. Turbocharger Outlet Pressure Circuit
15.1. Elevated Low Idle Override
16.1. Air Filter Restriction
17.1. Engine Overspeed
18.1. Low Oil Pressure Alarm
19.1. High Coolant Temperature Alarm
20.1. Throttle Backup Input Circuit
21.1. Ground Level Shutdown Input
22.1. User Defined Shutdown Circuit
23.1. Engine Oil Pressure Input Circuit

Electronic Control Module (ECM)

The ECM allows the ordinary switch input circuits that go to the ECM to have a tolerance for resistance and shorts between wires. These tolerances are the following items:

  • The ECM will tolerate resistance in any ordinary switch up to 2.5 ohms without malfunctioning.

  • The ECM will tolerate shorts to the ground or shorts between wires in any ordinary switch input that is 5000 ohms or more without malfunctioning.

The ECM draws a maximum of 10 amp at 24 volts from the electrical system. However, the ECM will function with less than 12 volts. A minimum of 9 volts is required by the ECM while the engine is cranking or running.

Power enters the ECM through the +Battery wire. Power exits through the −Battery wire. The −Battery wire is grounded to the engine block. The −Battery wire must be within 0.5 ohms of the machine frame ground. There must be a good, direct path to the −Battery terminal.

The ECM is protected against power surges on the 24 volt power supply.

Engine Speed/Timing Input Circuit

Engine speed is sensed by an electronic sensor. The same sensor is used for monitoring the position of the camshaft and engine speed . The speed/timing sensor has a self-adjusting pickup head. The signals are created as the timing reference ring rotates past the pickup (sliphead) of the engine speed/timing sensor. The timing reference ring is mounted on the rear of the left camshaft. A unique tooth pattern on the timing reference ring allows the ECM to determine the crankshaft position, the direction of rotation, and the speed. The ECM supplies the engine speed/timing sensor with 12.5 ± 1.0 VDC which is required for proper operation.

The output of the speed/timing sensor is a series of pulses. The frequency of the pulses is dependent upon the speed of the engine. The ECM interprets the frequency of the pulses as engine speed. The shape of the pulses is dependent upon the rotation position of the camshaft. The ECM reads the shape of the pulses in order to determine the position of the camshaft.

Coolant Temperature Input Circuit

The temperature of the engine coolant is measured by an electronic sensor. The sensor is mounted on the cover of the regulator housing. The signal from the sensor is used to modify the fueling of the engine. The signal is also used to modify the timing for an improved cold start and reduction in white smoke. The ECM supplies the coolant temperature sensor with 5.0 ± 0.5 VDC. The sensor's output voltage is 0.2 ± 4.6 VDC. This depends on the temperature of the engine's coolant.

Hydraulic Oil Temperature Input Circuit

Hydraulic oil temperature is measured by an electronic sensor that is mounted in the rear suction line near the hydraulic oil tank. The sensor signal is used to determine optimum fan speed for the hydraulic oil demand fan. The ECM supplies the hydraulic oil temperature sensor with 5.0 ± 0.5 VDC. The sensor output voltage is 0.5 to 4.5 VDC. The ECM interprets the output voltage as hydraulic oil temperature.

Throttle Switch Input Circuit

Desired engine speed is selected by the operator by using a ten position switch that is mounted in the cab area. The switch consists of four poles that connect to four switch inputs on the ECM through the vehicle wiring. Each pole is read as "grounded" or "open" by the ECM. The ECM compares the pattern of "grounded" or "open" switch poles to a preprogrammed table in memory in order to select the desired engine speed.

Automatic Engine Speed Control (AESC)

The AESC switch allows the operator to enable the automatic engine speed control. The AESC system reduces engine speed to 1350 rpm when the operator has not moved a hydraulic control for four seconds. The AESC switch also acts as a backup for the throttle switch.

User Defined Shutdown Circuit

The ECM reads this switch input. The ECM will terminate the fuel injection if the input is connected to the chassis ground. The shutdown is permanently recorded in the ECM as a logged event.

Aftercooler Temperature Input Circuit

The aftercooler temperature sensor is located in the elbow for the aftercooler at the rear of the engine. The sensor receives a 13 volt supply voltage from the ECM. The sensor produces a 5000 Hz PWM signal. The signal's pulse width is interpreted by the ECM as aftercooler temperature.

Gear Box Temperature Input Circuit

The gear box temperature sensor is located in the pump drive case at the rear of the engine. The sensor receives a 13 volt supply voltage from the ECM. The sensor produces a 5000 Hz PWM signal. The signal's pulse width is interpreted by the ECM as gear box oil temperature.

Demand Control Fan System Output Circuit

The demand fan control provides a 0 to 1.8 amp signal to the solenoid valve that controls the oil flow to the fan drive motor. A 1.8 amp signal sets oil flow in the fan drive to minimum resulting in minimum fan speed. Conversely, a 0 amp signal sets oil flow in the fan drive to maximum resulting in maximum fan speed. The ECM reads the engine coolant temperature sensor in order to control the fan speed.

Injector Output Circuits

An electrical signal from the ECM controls each electronic unit injector (EUI). This electrical signal determines the fuel injection timing. The duration of the electrical signal determines the quantity of fuel that is injected. The signal allows precise control of the injectors.

Atmospheric Pressure Input Circuit

Atmospheric pressure is monitored by the atmospheric pressure sensor. The sensor is located on the mounting bracket for the ECM. A 5.0 ± 0.5 VDC supply voltage is provided by the ECM. The output of the atmospheric pressure sensor is a DC signal. This signal has a range from 0.2 volts to 4.8 volts. The ECM interprets the output voltage as atmospheric pressure.

Turbocharger Inlet Pressure Circuit

The air pressure in the air induction system for the engine is monitored by the turbocharger inlet pressure sensors. The sensors are located in each air inlet tube. The ECM provides the sensor with a 5.0 ± 0.5 VDC supply voltage. The output of the turbocharger inlet pressure sensor is a DC voltage signal. The signal has a range from 0.2 volts to 4.8 volts. The ECM interprets the signal from this sensor as the inlet air pressure to the turbocharger compressors.

Turbocharger Outlet Pressure Circuit

The engine's air inlet manifold pressure is monitored by the turbocharger outlet pressure sensor. The sensor is located at the front of the engine. The sensor is mounted in a block on the bracket of the front water regulator housing. The sensor receives a 5.0 ± 0.5 VDC supply voltage from the ECM. The output of the sensor is a DC signal. The signal has a range from 0.2 volts to 4.8 volts. The signal is interpreted by the ECM as the absolute pressure of the inlet manifold.

Elevated Low Idle Override

Under some ambient operating temperatures without increased engine speed, the machine will not reach the proper operating temperature after start-up. This is due to the cooling capacity of the machine. The machine will cool below the proper operating temperature during idling.

The elevated idle is enabled when the transmission is in neutral and the parking brake is engaged. Neutral status and parking brake status are based on inputs over the data link. These inputs are from the transmission control. The activation of the elevated idle is delayed on the engine start-up or on the engine cooldown.

Air Filter Restriction

The air filter restriction is indicated by the VIMS display window when the pressure drop across the air cleaner filters exceeds the maximum allowable level. The monitoring control module receives the air restriction warning from the ECM through the data link.

Engine Overspeed

The ECM provides a signal to the machine's VIMS display window via the data link. This signal indicates whether the engine speed is at an acceptable level. A warning can be indicated on the VIMS display window. The warning is indicated with an action lamp and an alarm. Overspeed is activated when engine speed exceeds 2200 rpm. The warning remains active until the engine speed decreases to 1900 rpm.

Low Oil Pressure Alarm

The ECM provides a signal to the machine's VIMS display window via the data link. The signal indicates whether engine oil pressure is at an acceptable level for the operating condition. The ECM compares the actual engine oil pressure to an oil pressure map. The map is stored in the ECM memory. A warning is indicated on the VIMS display window if the engine oil pressure is less than the predetermined value from the map.

High Coolant Temperature Alarm

The ECM provides a signal to the machine's VIMS display window via the data link. The signal indicates the engine's coolant temperature. The coolant temperature is displayed in the indicator cluster. If the coolant temperature reaches the red area on the indicator, the VIMS module illuminates the action lamp.

The monitoring panel is supplied 24 volts by the machine's electrical system. The ECM closes the "High Coolant Temperature" output circuit when the coolant temperature is acceptable. The ECM will open the "High Coolant Temperature" output circuit if the coolant temperature is excessively high. A "High Coolant Temperature" indication will result on the VIMS module.

Throttle Backup Input Circuit

The throttle backup switch is used to increase engine speed to 1300 rpm when the electronic control module (ECM) receives an erroneous throttle position signal. This switch position is ignored unless the ECM determines that the throttle signal is incorrect.

If the switch is in the "OFF" position (open), the input line to the ECM will go to approximately 12 volts. If the switch is depressed the input line to the ECM is pulled to 0 volts (ground).

Ground Level Shutdown Input

The ground level shutdown switch is a single pole double throw. The ground level shutdown switch is used in order to shut down the engine from the ground level. The ground level shutdown switch allows the engine to be cranked without starting the engine. This procedure is used for servicing the engine. When the switch is down the switch is in Run Mode. When the switch is up the switch is in Shutdown Mode.

When the remote shutdown switch has been switched to the shutdown position the ECM power supply must be cycled before the engine will start. This is accomplished by turning the keyswitch to "OFF" and then turning the keyswitch back to the "START" position.

User Defined Shutdown Circuit

The ECM reads this switch input. The ECM will terminate the fuel injection if the input is connected to the chassis ground. The shutdown is permanently recorded in the ECM as a logged event.

Engine Oil Pressure Input Circuit

The engine oil pressure is monitored from the outlet on the engine oil filter. The 5.0 ± 0.5 VDC operating voltage for this sensor is supplied by the ECM. The output of the engine oil pressure sensor is a 0.14 to 4.42 volts DC signal. The voltage is dependent upon the engine oil pressure. The voltage is interpreted by the ECM as engine oil pressure.

Information System:

M316C, M318C and M322C Excavators and M318C and M322C Material Handlers Filter/Fluid Hours
5230B Excavator Machine Systems Gear Pump (Pump Drive Lubrication) - Disassemble
3500B Engines for 5130B and 5230B Excavators Digital Sensor Supply
HDB Series and M1 Series Heavy Duty Brushless Alternators Component Description
3500B Engines for 5130B and 5230B Excavators CAT Data Link
M316C, M318C and M322C Excavators and M318C and M322C Material Handlers Clock Adjustment
312C Excavator 3064 Engine Supplement Fuel Filter (Primary) and Fuel Filter Base - Remove and Install
M316C, M318C and M322C Excavators and M318C and M322C Material Handlers Main Menu
3500B Engines for 5130B and 5230B Excavators Analog Sensor Supply
312C Excavator 3064 Engine Supplement Fuel Priming Pump - Remove and Install
W345B Series II Material Handler Hydraulic System Control Valve (Stick Lowering)
312C Excavator 3064 Engine Supplement Air Conditioner Dryer - Remove and Install
M325B Material Handler Machine Systems Stick Cylinder - Disassemble
M325B Material Handler Machine Systems Stick Cylinder - Assemble
M325B Material Handler Machine Systems Boom Cylinder - Disassemble
5230B Excavator Machine Systems Gear Pump (Pump Drive Lubrication) - Assemble
W345B Series II Material Handler Hydraulic System Control Valve (Boom Lowering)
M325B Material Handler Machine Systems Boom Cylinder - Assemble
305 CR Mini Hydraulic Excavator Light Switches
325C L and 325C LN Excavator Lifting Capacities Lifting Capacities - 325C Excavator
3500B Engines for 5130B and 5230B Excavators Electrical Power Supply
M316C, M318C and M322C Excavators and M318C and M322C Material Handlers Boom/Stick/Bucket Combinations
M316C, M318C and M322C Excavators and M318C and M322C Material Handlers Plate Locations and Film Locations
305 CR Mini Hydraulic Excavator Window Wiper and Washer Control - If Equipped