D5R2 Track-Type Tractor Systems Electronic Control (Hydraulic System) Caterpillar


Electronic Control (Hydraulic System)
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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. Hydraulic Temperature Sensor
9.2. Switches
10.3. Implement lockout Switch
11.1. Outputs
12.2. Coils
13.3. Blade Float Detent
14.2. On/Off Solenoids
15.3. Implement Lockout Solenoid
16.1. Data Link
17.2. Cat Data Link
18.2. CAN Data Link

Electronic Control Modules

Machine ECM



Illustration 1g03307257


Illustration 2g01309473
ECM Connectors and Contacts

The Implement ECM determines actions that are based on input information and memory information. After the Implement ECM receives the input information, the ECM sends a corresponding response to the outputs. The inputs and outputs of the Implement 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 
10  Cat Data Link +  Cat Data Link + 
12  Sourcing Driver Output  Blade Float Detent Coil 
13  Battery Return  Battery - 
20  Cat Data Link -  Cat Data Link - 
23  Battery Return  Battery - 
26  Switch to Ground Input  Implement Lockout Switch (N/O) 
27  Switch to Ground Input  Implement Lockout Switch (N/C) 
30  Analog Input  Hydraulic Temperature Sensor 
31  Battery Power Input  Battery + 
38  Battery Power Input  Battery + 
39  Battery Power Input  Battery + 
44  Sensor Power Output  8V Supply 
45  Sensor Power Return  8V Return 
47  Battery Power Input  Battery + 
56  Sensor Power Return  10V Return 
57  Battery Return  Battery - 
60  Sourcing Driver Return  Implement Shutoff Solenoid Return 
61  Sourcing Driver Output  Implement Shutoff Solenoid 
69  Sensor Power Output  10V 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 Return  Blade Float Detent Coil Return 
22  Return  Sensor / Driver Return 
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.

Hydraulic Temperature Sensor



Illustration 3g03372390

The ECM receives signals from the hydraulic 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 hydraulic oil.

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.

Implement lockout Switch



Illustration 4g03346014

The implement lockout switch is a two pole switch. The switch has a normally connected and a normally open contact. When the switch is not depressed the normally connected contact is connected to the return, and the normally open contact floats to a high voltage state. When the switch is depressed, the normally open contact is connected to the return and the normally connected contact floats to a high voltage state. Based on the voltage state of the two ECM contacts, the ECM determines if the switch is depressed.

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.

Coils

Blade Float Detent



Illustration 5g03675233

The blade float detent is an electrical coil that is energized by the ECM. When the coil is energized, the solenoid creates an electromagnetic field that holds the implement lever in the FLOAT position.

On/Off Solenoids

Implement Lockout Solenoid



Illustration 6g03422260

The implement lockout switch is an on/off type solenoid. The solenoid is activated by the ECM depending on operating conditions and operator request. When the solenoid is energized, the solenoid opens and allows hydraulic oil to flow to the implement system.

Data Link

Electronic communication between the Machine Control ECM, the Implement Control 2 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 two types of data link systems.

  • Cat Data Link

  • SAE J1939 (CAN) Data Link

The two types of data links are the main structure for communication between all of the control modules on the machine.

The SAE J1939 Data Link circuit is mostly used for faster operational communication between the control modules on the machine. The Cat Data Link is used for some of the internal communication that does not require the faster speeds and is used for communication with external devices such as the AVSpare Electronic Technician (Cat ET) service tool.

Cat Data Link

The Cat Data Link is an input/output of the ECM. The data link uses the connector for the service port in order to communicate with the AVSpare Electronic Technician. A data link connection is provided for the product link.

Note: The control for the product link provides a global positioning system for the machine.

The data link is bidirectional. The bidirectional link allows the ECM to input information and output information. The data link consists of the following parts: internal ECM circuits, the related harness wiring, the service tool connector and the connector for the product link. The Cat Data Link connects to the ECM at contact J1-10 (wire 893-GN(Green)) and contact J1-20 (wire 892-BR(Brown)).

  • The ECM receives commands from the Cat ET in order to change the operating modes. The Cat ET will read the service codes that are stored in the memory of the ECM. The Cat ET will clear the service codes that are stored in the memory of the ECM.

  • The ECM sends the input and the output information to the AVSpare ET.

Note: An electronic control module that uses the Cat Data Link will have a module identifier. The MID for the Machine Electronic Control Module is 039.

CAN Data Link

A data link is required for communication with the service tool (Cat ET) and the electronic control modules as well as instrument clusters and other devices that use this communications protocol. The data link is not used in order to broadcast any diagnostic information.

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