7/21/2019 966 f Loader http://slidepdf.com/reader/full/966-f-loader 1/14 4YG 966F WHEEL LOADER Systems Operation Media Number SENR5922-02 Publication Date 1994/10/03 Update Date 2001/06/19 Components DescriptionThe same transmission control is used on a variety of models. All of the following electrical components are not present on every machine. The control recognizes the machine on which it is installed and knows which components are present. For the location of components see the Electrical System Schematic in the machine Service Manual. Electronic Transmission ControlPage 1 of 14 Copyright 1991, 2012 Caterpillar Inc. All Rights Reserved. 25/12/2012 file://C:\SIS\TMP\sis5D9C1prt.html
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4YG 966F WHEEL LOADER Systems Operation
Media Number SENR5922-02 Publication Date 1994/10/03 Update Date 2001/06/19
Components Description
The same transmission control is used on a variety of models. All of the following electrical components are not present onevery machine. The control recognizes the machine on which it is installed and knows which components are present. For thelocation of components see the Electrical System Schematic in the machine Service Manual.
Electronic Transmission Control
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NOTE: The preceding chart has been revised.
Electronic circuits within the control make shifting decisions and control the transmission solenoid valves. The control inputs
and outputs are connected to the machine harness wiring through a 40 contact connector.
Input/Output
The CAT data link is bidirectional, allowing the control to receive and send information. The purpose of the data link is tocommunicate with the Computerized Monitoring System (CMS). The data link is not a visible component. It consists ofinternal control circuits and the connecting harness wiring.
The transmission control receives harness code information from CMS.
The transmission control sends engine speed, transmission speed, transmission gear, transmission direction and transmission
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control faults to CMS to be shown on the CMS display.
All electronic controls that use the data link have a module identifier (MID). The MID for this transmission control is thenumber 81.
Inputs
Several types of inputs provide information to the control.
Operational
The operational inputs provide information about operator requests to the control. These inputs receive information from theshift handle, downshift, ride control and auto/manual switches. These switches provide an open (floating), ground or batterysignal, to the inputs of the control.
Option
The option inputs (connector contacts 25, 27 and 30) tell the control what options the machine is equipped with. These inputsare either open or grounded by the options code plug. For the option code of the machine being serviced, see the Option Codechart on the Electrical System Schematic in the machine Service Manual.
Service
The service inputs (connector contacts 28 and 29) control the mode of operation and certain diagnostic functions. Groundingservice input (connector contact 28) and clear input (connector contact 29) at the same time, initiates changing the controldisplay mode. Removing ground from these two inputs locks the control in the selected mode. Other diagnostic functions arealso performed when the service inputs are grounded and/or opened at the proper time. For more information, see the topicDisplay Modes in the Systems Operation section.
Sensor
At each sensor input, an AC signal is present which represents the transmission speed (connector contact 5) and engine speed(connector contact 6). The control measures the frequency (Hz) of the AC signals to determine the transmission and engine
speed. The control uses this speed information to make shifting decisions.
Outputs
Display
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Electronic Transmission Control Display Area
(1) Power indicator (green). (2) Readout (component identifier and failure mode identifier). (3) Service mode indicator(yellow). (4) Fault present indicator (red).
The display shows the operating status of the electronic transmission control system and diagnostic information.
Solenoid
The control sends a voltage to the solenoid outputs to energize solenoids that control various machine functions. Thesefunctions are transmission gear selection, ride control activation, engine horsepower selection and air inlet heater activation(using a relay).
Switches
Switches provide information (input) to the control. Switches are two state devices. The two states are:
· Closed - the switch closes a circuit to the control input.
· Open - the switch opens a circuit to the control input.
Park Brake Switch (If Equipped)
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Park Brake Switch
(1) Schematic symbol. (2) Switch.
The purpose of park brake switch (2) is to tell the control when the park brake is engaged. The control also sends thisinformation to the Computerized Monitoring System (CMS). Park brake switch (2) has two input connections to the control;park brake N/C at connector contact 4 and downshift N/O at connector contact 3. When the park brake is engaged, the parkbrake N/C circuit is open and the park brake N/O circuit is closed to ground. When the switch is not activated, the park brakeN/C circuit is closed to ground and the park brake N/O circuit is open.
NOTE: A two pole switch is used for diagnostic purposes. If the two poles are ever in the same state (open or grounded), thecontrol knows a circuit failure is present.
Downshift Switch
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Downshift Switch
(1) Switch. (2) Schematic symbol.
The purpose of downshift switch (1) is to tell the control that the operator wants the transmission to downshift one gear.Downshift switch (1) has two input connections to the control; downshift N/C at connector contact 23 and downshift N/O atconnector contact 22. When the operator presses downshift switch (1), the downshift N/C circuit is open and the downshiftN/O circuit is closed to ground. When the switch is not activated, the downshift N/C circuit is closed to ground and the
downshift N/O circuit is open.
NOTE: A two pole switch is used for diagnostic purposes. If the two poles are ever in the same state (open or grounded), thecontrol knows a circuit failure is present. This fault is then shown on the diagnostic indicator; see Diagnostic IndicatorOperation.
Auto/Manual Switch
Auto/Manual Switch
(1) Switch. (2) Schematic symbol.
The purpose of auto/manual switch (1) is to tell the control which shift mode the operator wants the control to operate in.Auto/manual switch (1) has two input connections to the control; auto/manual N/C at connector contact 20 and auto/manualN/O at connector contact 21. When the operator selects AUTO mode, the auto/manual N/O circuit is open and theauto/manual N/C circuit is closed to ground. When MANUAL mode is selected, the auto/manual N/O circuit is closed toground and the auto/manual N/C circuit is open.
Air Inlet Heater Switch (If Equipped)
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Air Inlet Heater Switch
(1) Switch. (2) Schematic symbol.
The purpose of air inlet heater switch (1) is to tell the control that the operator wants to continue to heat the inlet air. Air inletheater switch (1) has one input connection to the control at connector contact 7. When the operator holds the switch in theheat position, the input to the control is closed to ground. With the switch in the OFF position, the input to the control isopen.
Ride Control Switch (If Equipped)
Ride Switch
(1) Switch. (2) Schematic symbol.
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Machines With Air Over Hydraulic Brakes
The purpose of ride control switch (1) is to tell the control which ride mode (AUTO/ON/OFF) the operator wants the controlto operate in. Ride control switch (1) has three input connections to the control; input 1 at connector contact 10, input 2 atconnector contact 11 and input 3 at connector contact 26. When the operator selects AUTO mode, input 2 is open, input 1 isclosed to +battery and input 3 is closed to ground. When ON mode is selected, input 2 is closed to +battery, input 1 is openand input 3 is open. When OFF is selected, input 2 is open, input 1 is closed to +battery and input 3 is closed to ground.
Machines With Hydraulic Over Hydraulic Brakes
The purpose of ride control switch (1) is to tell the control which ride mode (AUTO/ON/OFF) the operator wants the controlto operate in. Ride control switch (1) has two input connections to the control; input 2 at connector contact 24 and input 3 atconnector contact 26. When the operator selects AUTO mode, input 2 is closed to ground and input 3 is open. When ONmode is selected, input 2 is open and input 3 is closed to ground. When OFF is selected, input 2 and input 3 are closed toground.
Shift Handle Switches
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The shift handle switches are inputs to the control and connect to contacts 12 through 19. The purpose of the switches is totell the control what gear and direction the operator has selected with the shift handle.
The shift handle switches close gear and direction inputs on the control to ground and +battery. The gear and directionselected are the only closed switches; the other direction and gear switches are open.
Neutralizer Switch
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During normal operation, neutralizer switch (1) closes the neutralizer input of the shift handle (9 contact connector - contact1) to battery voltage. Depressing the brake pedal increases the brake oil pressure and opens the neutralizer input line. Withthis line open, the shift handle cannot close either direction solenoid input of the control (connector contacts 18 and 19) tobattery voltage. Without battery voltage at one of these inputs the control neutralizes the transmission. With the transmissionneutralized, the direction solenoids are not activated.
Neutralizer Override Switch
Neutralizer Override Switch
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When activated, neutralizer override switch (1) closes the neutralizer input of the shift handle (9 contact connector - contact1) to battery voltage whether the brakes are applied or not. This switch is used to disable the neutralizer switch whenneutralizing the transmission during braking is not desired.
Sensors
Sensor (Typical Example)
(1) Sensor. (2) Schematic symbol.
The engine and transmission speed sensors are located on the flywheel housing and the transmission housing respectively. Asgear teeth pass the end of each sensor, an AC voltage is produced. The frequency of the voltage is proportional to the speed
of the passing gear teeth. The control uses these signals to make shifting decisions.
Solenoids
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The purpose of the transmission solenoids is to turn on and off the oil flow to the clutches in the transmission. When adirection and gear are selected by the operator or the control, the control activates the appropriate solenoids. For movementof the machine two solenoids are activated; one for direction and one for gear. When activated, a solenoid receives voltagefrom the control. When in neutral, the 4th gear solenoid is activated.
The purpose of the ride control solenoid is to turn on and off the hydraulic oil flow to and from the load dampening system.
The dual horsepower/engine shutdown solenoid is one solenoid with two coils, one for each function. The purpose of the dual
horsepower portion is to limit the engine rack movement. When high horsepower is activated the control energizes the dualhorsepower coil of the solenoid. This allows the engine rack to open more and allows greater fuel flow, increasing the enginehorsepower.
The solenoids have a connector with two contacts. One contact receives power from the corresponding connector contact (31through 38) of the control. The other contact of all the solenoids join together and return to connector contact 39 of thecontrol.
Air Inlet Heater Relay
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The purpose of the air inlet heater relay is to turn on and off the current flow to the air inlet heater. When the controldetermines that the air inlet heater should be engaged, the control activates the air inlet heater relay output (connector contact7), which energizes the air inlet heater relay.
The relay has a connector with two contacts. One contact receives power from the control (connector contact 7). The othercontact returns to connector contact 39 of the control.
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