D7E Track-Type Tractor Hydraulic, HVAC and Electrical Systems Caterpillar

Illustration 1	g02340241
Implement ECM (View: appearance cover removed, facing the rear of the cab behind the operator seat on the lower left-hand side) (1) Implement ECM (2) J2 machine harness connector (3) J1 machine harness connector

Illustration 2	g01309473
ECM Connectors and Contacts

The Track Type Tractor machines are equipped with an Implement ECM module that is mounted inside the cab behind the seat.

The Implement ECM decision making ability is based on input data and programming parameters that have been flashed to the ECM memory. After the Implement ECM receives the input data, the ECM determines the correct response. The Implement ECM then sends an output signal to the appropriate output device. The internal input and output circuits of the ECM are connected to the machine wiring harness with two 70 pin connectors. The connectors are labeled J1 and J2.

Note: The ECM is not serviceable. If the ECM is damaged, the ECM must be replaced. The failure rate for the ECM is low. If a possible ECM failure is suspected, ensure that all of the other possible causes of a particular problem have been investigated. Contact the Technical Communicator at your dealership for a possible consultation with Caterpillar before replacing the ECM.

ECM Pull Up Voltage

To aid in diagnostics of certain types of electrical circuits controlled by the ECM, an internal "pull up voltage" is connected to sensor signal input contacts. An above normal voltage is internally connected to the ECM signal input circuit through a resistor.

During normal operation, the switch or sensor signal will perform one of the following:

• Hold the circuit low.

• Hold the circuit at a certain signal amplitude.

The following circuit conditions will allow the circuit to be pulled high by the ECM "pull up voltage":

• A loss of power to the component

• A disconnect or an open circuit

The above conditions will result in an above normal voltage at the contact of the ECM. When the circuit is pulled high by the ECM "pull up voltage", an FMI 03 diagnostic code indicates that the following condition exists:

• Voltage is above normal

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

• Pulse Width Modulated (PWM) sensor input circuits

• Switch-to-ground switch input circuits

• Active analog (voltage) input signal circuits

• Passive analog (resistance) input signal circuits

ECM Pull Down Voltage

To aid in diagnostics of electrical circuits 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. The following circuit conditions will allow the circuit to be pulled low by the ECM "pull down voltage":

• A loss of power to the switch supply voltage

• A disconnection in the switch circuit

• An open circuit

The above conditions will result in a below normal voltage at the contact of the ECM. When the circuit is pulled low by the ECM "pull down voltage", an FMI 04 diagnostic code indicates that the condition exists:

• Voltage is below normal

Inputs

The machine has several different types of input devices. The ECM receives machine status information from the input devices. The ECM determines the correct output action that is required based on memory and software parameters. The machine utilizes the following types of inputs:

• Switch type

• 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

• Frequency input signals

Note: Tables 1 and 2show all possible inputs to the Implement ECM module for the 70-pin connectors

Outputs

The ECM sends electrical signals through the outputs. The outputs can create an action or the outputs can provide information to the ECM. The ECM can send output signals to the system components in one of several different electrical signal types such as:

• Driver outputs

• Sinking driver outputs

• Sensor power supply outputs

• Data link outputs

Note: Tables 1 and 2show all possible outputs to the Implement ECM module for the 70-pin connectors

Input/Output

Communication between the Implement ECM modules and between the other ECM 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 ECM supports two types of data link systems.

• Cat Data Link

• SAE J1939 Data Link

The two types of data links are the main structure for communication between all of the control modules on the machine. A machine may have more than one CAN data link. Dedicated CAN data link circuits can be used for communication between specific controls on the machine.

Communication between the Implement ECM and other ECMs on the machine is conducted over the J1939 data link circuit. Each ECM use the Cat data link to send and receive information from Caterpillar Electronic Technician (ET).

A module identifier (MID) is assigned to each ECM. The MID code for the Implement ECM is listed below:

Implement ECM - MID 082

Note: All diagnostic codes for the components in the implement control system are activated by the Implement ECM (MID 082).

Note: Tables 1 and 2show every possible connection for the Implement ECM module. Depending on the attachments that are installed on your machine, some of the circuits may not be present.