D7E Track-Type Tractor Systems Electronic Control (Power Train System) Caterpillar


Electronic Control (Power Train System)
`
1.1. Electronic Control Modules
2.2. Machine ECM
3.2. ECM Pull Up Voltage
4.2. ECM Pull Down Voltage
5.1. Pin Locations
6.1. Inputs
7.2. Sensors
8.3. Engine Speed Sensor
9.3. Power Train Tank Oil Temperature Sensor
10.3. Separate Circuit Cooling System Coolant Temperature Sensor
11.3. Separate Circuit Coolant Pressure Sensor
12.3. Power Train Lube Pressure Sensor
13.3. Throttle and Bi-Direction Control
14.3. Travel Control Pedal Position Sensor
15.3. Thumbwheel Sensor
16.3. Forward Neutral Reverse Selector
17.2. Switches
18.3. Parking Brake
19.3. Speed Set/Recall Switch
20.1. Outputs
21.2. Proportional Solenoids
22.3. Brake Solenoid
23.2. On/Off Solenoid
24.3. Brake Dump Solenoid
25.2. Backup Alarm
26.1. Data Link

Electronic Control Modules

Machine ECM



Illustration 1g03307257


Illustration 2g01309473
ECM Connectors and Contacts

The Machine ECM determines actions that are based on input information and memory information. After the Machine ECM receives the input information, the ECM sends a corresponding response to the outputs. The inputs and outputs of the Machine ECM are connected to the machine harness by two 70 contact connectors (J1 and J2). The ECM sends the information to the AVSpare Electronic Technician (Cat ET) on the Cat Data Link.

Note: The ECM is not serviceable. The ECM must be replaced if the ECM is damaged. Replace the ECM if a failure is diagnosed.

ECM Pull Up Voltage

In order to aid in diagnostics of certain types of electrical circuits that are controlled by the ECM, an internal "pull up voltage" is connected to ECM switch and sensor signal input contacts. An above normal voltage is internally connected to the ECM signal input circuit through a resister.

During normal operation, the switch or sensor signal will hold the circuit low or at a certain signal amplitude, however, circuit conditions such as a loss of power to the component, a disconnection, or an open circuit will allow the circuit to be pulled high by the ECM pull up voltage. This condition will result in an above normal voltage condition at the ECM contact. As a result, the ECM will activate an FMI 03 (voltage above normal) diagnostic code for the affected circuit.

The types of ECM input circuits that have pull up voltage present are:

  • Pulse Width Modulated (PWM) sensor input circuits

  • Switch to Ground Input switch input circuits

  • Active analog (voltage) input signal circuits

  • Passive analog (resistance) input signal circuits

ECM Pull Down Voltage

In order to aid in diagnostics of electrical circuits that are controlled by the ECM, an internal "pull down voltage" is connected to ECM switch to battery type input circuits.

During normal operation, the switch contacts that are allowing the connection to a voltage source will hold the circuit high. When circuit conditions such as a loss of power to the switch supply voltage, a disconnection in the switch circuit or an open circuit will allow the circuit to be pulled low by the ECM pull down voltage. This condition will result in a below normal voltage condition at the ECM contact. As a result, the ECM will activate an FMI 04 (voltage below normal) diagnostic code for the affected circuit.

Pin Locations

Table 1
Machine ECM Contact Description J1 Contact Descriptions(1) 
No.(2)  Type  Function 
Differential Speed Input (+)  Engine Speed Sensor + 
Differential Speed Input (-)  Engine Speed Sensor - 
11  Sensor Power Output  5V Sensor Supply 
13  Battery Return  Battery - 
21  Sensor Power Return  5V Sensor Return 
23  Battery Return  Battery - 
29  Analog Input  Power Train Oil Tank Temperature Sensor 
30  Analog Input  Separate Circuit Coolant Temperature Sensor 
31  Battery Power Input  Battery + 
35  Switch to Ground Input  Parking Brake Switch (N/O) 
37  Analog Input  Power Train Lubrication Pressure Sensor 
38  Battery Power Input  Battery + 
39  Battery Power Input  Battery + 
40  Switch to Ground Input  Parking Brake Switch (N/C) 
44  Sensor Power Output  8 V Sensor Supply 
45  Sensor Power Return  8 V Sensor Return 
47  Battery Power Input  Battery + 
55  Souring Driver Return  Proportional Brake Solenoid Return 
56  Sensor Power Return  10V Return 
57  Battery Return  Battery - 
58  Sourcing Driver Output  Proportional Brake Solenoid 
60  Sourcing Driver Return  PWM Driver 5-8 Return 
65  Sourcing Driver Output  Proportional Brake Valve Solenoid 
66  Sourcing Driver Output  Transmission Forward Clutch 
69  Sensory Power Output  10V Sensor Supply 
70  Battery Return  Battery - 
(1) Contacts that are not listed are not used.
(2) The connector contacts that are not listed are not used.

Table 2
Machine ECM Contact Description J2(1) 
No.(2)  Type  Function 
Sourcing Driver Output  Brake Dump Valve Solenoid 
Sourcing Driver Return  Brake Dump Valve Solenoid 
Sourcing Driver Output  Backup Alarm 
Sourcing Driver Return  Load Return 2 
22  Return  Sensor / Driver Return 
33  PWM Input  Throttle 
38  Switch To Ground Input  Speed Set/Recall (N/O) 
39  Switch To Ground Input  Speed Set/Recall (N/C) 
42  PWM Input  Thumbwheel PWM Shift 
43  PWM Input  Travel Control Pedal Sensor 
48  PWM Input  FNR 1 
49  PWM Input  FNR 2 
51  PWM Input  Bi-Directional Shift 
58  Analog Input  Separate Circuit Coolant Pressure Sensor 
67  CAN Data Link +  CAN A Data Link + 
68  CAN Data Link -  CAN A Data Link - 
(1) The ECM responds to an active input only when all of the necessary conditions are satisfied.
(2) The connector contacts that are not listed are not used.

Inputs

The machine has several different types of input devices. The ECM receives machine status information from the input devices and determines the correct output action that is needed in order to control machine operations based on memory and software parameters. The machine utilizes the following types of inputs: switch type and sensor type.

Switches provide signals to the switch inputs of the ECM. The possible outputs of a switch are listed: an open signal, a grounded signal and + battery signal.

Sensors provide an electrical signal to the ECM that constantly changes. The sensor input to the ECM can be one of several different types of electrical signals such as: pulse width modulated (PWM) signals, voltage signals and frequency input signals. Each possible input to the ECM is listed in the tables for the 70-pin connectors.

Inputs provide information to the ECM in the form of sensors or switches.

Sensors

Sensors provide information to the ECM about the intent of the operator or changing conditions. The sensor signal changes proportionally to the changing of operator input or changing conditions. The following types of sensor signals are used by the ECM.

Frequency - The sensor produces a signal and the frequency (Hz) varies as the condition changes.

Pulse width modulated - The sensor produces a signal. The duty cycle of the signal varies as the condition changes. The frequency of this signal is constant.

Analog - The ECM measures the voltage that is associated to a specific condition of the control.

Engine Speed Sensor



Illustration 3g03718385

The ECM receives signals from the engine speed sensor as a frequency signal. The engine speed sensor is a passive sensor. The signal indicates the rotational speed of the engine. The signal is generated by a gear passing in front of the sensor, with one full pulse generated per tooth on the gear. The signal is low when a gear tooth is in front of the sensor and high when in a valley.

Power Train Tank Oil Temperature Sensor



Illustration 4g03345886

The ECM receives signals from the power train tank oil temperature sensor as an analog signal. The sensor is a passive sensor. The voltage output of the sensor changes proportionally to the temperature of the torque converter oil.

Separate Circuit Cooling System Coolant Temperature Sensor



Illustration 5g03372390

The ECM receives signals from the separate circuit cooling system coolant temperature sensor as an analog signal. The sensor is a passive sensor. The voltage output of the sensor changes proportionally to the temperature of the coolant.

Separate Circuit Coolant Pressure Sensor



Illustration 6g03718548

The separate circuit coolant pressure sensor is an active analog sensor. The voltage of the signal varies proportionally to the pressure of the coolant. The ECM receives the signal and interprets the voltage level to determine the pressure of the coolant.

Power Train Lube Pressure Sensor



Illustration 7g03718616

The power train lube pressure sensor is an active analog sensor. The voltage of the signal varies proportionally to the pressure of the lubrication. The ECM receives the signal and interprets the voltage level to determine the pressure of the lubrication.

Throttle and Bi-Direction Control



Illustration 8g03719124

The throttle and bi-direction control selectors are active pulse width modulated sensors. The duty cycle of the signal varies based on the position of the selectors. Use the table below to determine duty cycle and position relationship.

Table 3
Switch Position  Throttle Duty Cycle  Bi Direction Duty Cycle 
10%  N/A 
23%  23% 
36%  36% 
49%  49% 
62%  62% 
75%  75% 
88%  N/A 

Travel Control Pedal Position Sensor



Illustration 9g03373852

The travel control pedal position sensor is an active pulse width position sensor. The sensor sends a pulse width modulated signal to the ECM. The signal allows the ECM to determine the operator input request for ground speed reduction based on the position of the pedal.

Thumbwheel Sensor



Illustration 10g03373957

The thumbwheel sensor is an active pulse width modulated sensor. The sensor sends a pulse width modulated signal to the ECM. The duty cycle of the signal is proportional to the position of the thumbwheel. The signal allows the ECM to determine the operator input request for ground speed.

Forward Neutral Reverse Selector

The forward neutral reverse (FNR) selector generates two PWM signals. Based on the duty cycle of the two signals, the ECM determines the operator request for forward, reverse, or neutral.

Switches

Switches provide an open signal, a ground signal, or a +battery signal to the inputs of the ECM. Switches are open or closed.

  • When a switch is open, no signal is provided to the corresponding input of the ECM. This “no signal” condition is also called “floating”.

  • When a switch is closed, a ground signal or a +battery signal is provided to the corresponding input of the ECM.

Parking Brake



Illustration 11g03372717

The parking brake switch is a two position switch with a normally open contact and a normally closed contact. The contacts provide switch to ground inputs to the ECM. Through these contacts, the ECM can determine if the operator has engaged or disengaged the parking brake switch. The parking brake switch directly controls the action of the parking brake system, by either opening or closing the driver side circuit on the brake solenoid.

Speed Set/Recall Switch



Illustration 12g03373911

The speed set/recall switch is a momentary switch with a normally open contact and a normally closed contact. The contacts provide switch to ground inputs to the ECM. Through these contacts, the ECM can determine if the switch is depressed or not. The ECM then uses internal programming to control the speed set/recall feature based on the operation of the switch.

Outputs

The ECM responds to decisions by sending electrical signals to the outputs. The outputs can create an action or the outputs can provide information to the operator or the service technician.

Proportional Solenoids

Brake Solenoid



Illustration 13g03372925

The brake solenoid is designed to control the flow of brake oil to the brakes. The brakes are spring applied and hydraulically released. When the solenoid is not engaged or receiving a low duty cycle signal, the solenoid does not allow brake oil to disengage the brakes. As the duty cycle of the signal to the solenoid increases, the solenoid allows some flow and the brakes begin to release. When the duty cycle of the signal to the solenoid is at the maximum, the flow of brake oil fully releases the brakes. The engagement of the brakes is inversely proportional to the duty cycle of the signal sent by the ECM.

Note: The solenoid coils are not designed to operate using 24 DCV directly. The ECM sends a PWM signal of 24 V at a duty cycle that will provide the necessary current to the solenoid coils. Do NOT activate the coils by using 24 DCV (+battery). The life of the coils will be reduced drastically. A source of 12 DCV should be used, if the coils must be activated by not using the ECM.

On/Off Solenoid

Brake Dump Solenoid



Illustration 14g03423744

The brake dump solenoid is an on/off solenoid valve. The solenoid is activated when the limit switch on the brake pedal is activated. The solenoid controls if the brake hydraulic oil is being directed to the tank, or allowed to be distributed by the brake solenoid.

Backup Alarm



Illustration 15g03350044

The backup alarm is controlled by the power train ECM. When in the REVERSE position, the backup alarm sounds. The alarm is driven by the ECM.

Data Link

Electronic communication between the Implement ECM, Machine ECM, Engine ECM, and the other control modules on the machine is conducted over data link circuits. The data link circuits allow the sharing of information with other electronic control modules. The data link circuits are bidirectional. The data link circuit allows the ECM to send information and to receive information.

The electronic communication system consists of multiple CAN datalink systems.

The SAE J1939 CAN Data Link circuit is separated into different groups. "CAN A" is connected to all of the ECMs on the machine, and is used primarily for information and service purposes, such as the AVSpare Electronic Technician (AVS ET). The other data link systems are high speed data links used for machine control purposes.

Information System:

Fast Fill Hose Inspection On Certain D8TTrack-Type Tractors Equipped With a Fast Fuel Attachment{1273, 1710}
C280 Marine Engines Secondary ECM Assumes Control
3500E EPA Tier 4 Final and IMO-II/III Switchable Marine Engines Engine Control Switch - Test
3516B Generator Set Engines with Dynamic Gas Blending Intake Manifold Air Temperature Is High
950M and 962M Wheel Loaders Power Train, Steering, Braking, Hydraulic, and Machine Systems Steering Control Valve
D7E Track-Type Tractor Engine Oil and Filter - Change
950 GC Wheel Loader Power Train Trunnion Support (Oscillating Axle, Rear) - Remove and Install
3516B Generator Set Engines with Dynamic Gas Blending Camshaft Timing
950M and 962M Wheel Loaders Power Train, Steering, Braking, Hydraulic, and Machine Systems Transfer Gear Bearing Preload - Adjust
2014/12/19 The AccuGrade Blade Angle Sensor Bracket Has Been Relocated and Has a New Designed Cover On Certain D6K2 and D6N Track-Type Tractors {6052, 6060, 6701}
950 GC Wheel Loader Power Train Fixed Axle (Front) - Remove and Install
525D, 535D, 545D, 555D Wheel Skidder Engine Operation
2014/10/16 New Ejector Cylinder Group is Now Used on Certain 631G and 637G Wheel Tractor-Scrapers {5305}
D4, D6K2 and D6K Track-Type Tractor Systems Electronic Control (Hydraulic System)
C175-16 Locomotive Engine Configuration Parameters
980L Medium Wheel Loader Power Train, Steering, Braking, Hydraulic, and Machine Systems Transmission Speed for Forward Directional Shift - Program
980L Medium Wheel Loader Power Train, Steering, Braking, Hydraulic, and Machine Systems Transmission Speed for Reverse Directional Shift - Program
950 GC Wheel Loader Power Train Trunnion Support (Oscillating Axle, Front) - Remove and Install
3512E Petroleum Engines Engine Governing - Adjust
Relocation Procedure of the Engine Outlet NOx Sensor On Certain 834K, 836K, and 988K Machines{7490}
2014/10/23 Improved Woodchip Screens are now used on D8T Track-Type Tractors Equipped with Quick Release Radiator Grills {7170}
986H Wheel Loader Differential and Bevel Gear - Disassemble
Instrument Display Turn Signal Indicators Do Not Blink When the Signal Switch is Activated{1430}
Procedure to Install LED Lights on AD30 Underground Articulated Trucks{1429, 1434}