538, 548 and 558 Forest Machine Connector Contact Description Caterpillar


Connector Contact Description
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538, 548 and 558 Forest Machine [M0066266]
ELECTRICAL AND STARTING SYSTEM
WIRING GP
1.1. ECM Pull Up Voltage
2.1. ECM Pull Down Voltage
3.1. Inputs
4.1. Outputs
5.1. Input/Output
6.1. Machine ECM
7.1. Switch Panel

The Machine ECM will make decisions that are based on input data information and programming parameters that have been flashed to the ECM memory. After the ECM receives the input information, the ECM determines the correct response and sends an output signal to the appropriate device. The internal input circuits and the internal output circuits of the ECM are connected to the machine wiring harness by two 54 contact connectors (J1 and J2).

Note: The ECM is not serviceable. If the ECM is damaged, the ECM must be replaced. The ECM failure is unlikely. If the ECM failure is suspected, contact the Technical Communicator at a local dealership for possible consultation with AVSpare before replacing the ECM. Replace the ECM only after all of the other possible causes of a particular problem have been investigated.

ECM Pull Up Voltage

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 resistor.

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. The pull up voltage 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 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 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. The pull down voltage 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.

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 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 Machine ECM is listed in the tables for the 54-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, and data link outputs. The possible outputs for the Machine ECM are listed in the tables for the 54-pin connectors.

Input/Output

Communication between the Machine 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 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 the control modules on the machine. More than one CAN data link system can be present on a machine. Dedicated CAN data link circuits can be used for communication between specific controls on the machine.

Communication between the Machine ECM and the other control modules on the machine are conducted over the J1939 Data Link circuit that is connected to each control module. The ECMs use the Cat Data Link to send and receive information from the Cat® Electronic Technician (Cat ET) Service Tool.

A module identifier (MID) is assigned to each ECM on a machine. The MID for the Machine ECM is 299.

Note: The following tables list every possible connection for the Machine ECM. Depending on the attachments that are installed on your machine, some of the listed circuits may not be present.

Machine ECM

Table 1
Contact Description for Connector J1 
No.  Function  Type 
+Battery  Battery (+) 
Ground  Ground 
Swing Brake Solenoid  On/Off Solenoid 
Backup Switch  Power 
11  Left J/S Switch 1 (Upper)  Switch to Ground 
12  Left J/S Switch 2 (Fore)/Intelligent Hammer Enable Switch  Switch to Ground 
13  +Battery  Battery (+) 
14  Ground  Ground 
17  Boom Down Control Press Sensor  PWM 
21  Right J/S Switch 1 (Upper)  Switch to Ground 
22  Right J/S Switch 2 (Fore)/Smart Boom Cancel  Switch to Ground 
23  Key Switch  Key Switch 
25  Travel Speed Change Solenoid  On/Off Driver 
27  Power Supply for Sensor (8V)  Power 
29  Left Travel Pressure Switch  Switch to Ground 
30  Right Travel Pressure Switch  Switch to Ground 
32  Bucket In Pressure Switch for Crane  Switch to Ground 
33  Hydraulic Lock Solenoid  On/Off Driver 
35  Swing Control Pressure Sensor  PWM 
36  Boom Cylinder Head Pressure Sensor  PWM 
39  Straight Travel Pressure Switch  Switch to Ground 
40  One Touch Low Idle Switch  Switch to Ground 
43  Straight Travel Solenoid  On/Off Driver 
48  NFC 1 Pressure Sensor  PWM/STG 
49  NFC 2 Pressure Sensor  PWM/STG 
51  Thumb Wheel - LH / Left J/S Switch 4  PWM 
52  Thumb Wheel - RH / Right J/S Switch 4  PWM 
53  Pump 1 Pressure Sensor  PWM 
54  Pump 2 Pressure Sensor  PWM 

Table 2
Contact Description for Connector J2 
No.  Function  Type 
ATT Stem1 Extend EPRV/REPRV for TCS  PRV Driver 
ATT Stem2 Retract EPRV/REPRV for TCS  PRV Driver 
ATT Stem2 Extend EPRV/REPRV for TCS  PRV Driver 
PS Pressure EPRV  PRV Driver 
Boom Regen REPRV  PRV Driver 
13  ATT Stem1 Retract EPRV/REPRV for TCS  PRV Driver 
16  CDL -  Input/Output 
19  PRV Return  Ground 
21  PRV Return  Ground 
22  PRV Return  Ground 
25  CDL +  Input/Output 
27  Hydraulic Lock Cancel Switch  Switch to Battery 
28  Swing Priority Solenoid for Gen1  PRV Driver 
43  ESP Pump 2 Solenoid  PRV Driver 
47  CAN (J1939) Data Link +  Input/Output 
48  CAN (J1939) Data Link -  Input/Output 
50  Machine Can Data Link +  Input/Output 
51  Machine Can Data Link -  Input/Output 
53  ESP Pump 1 Solenoid  PRV Driver 

Switch Panel

Table 3
Contact Description for Connector C1 
No.  Function  Type 
Fuel Level Sensor  Input 
Hydraulic Oil Temperature Sensor  Input 
Analog Return  Ground 
A/C Unit  Input 
Capsule Filter Plugged Switch  Switch to Ground 
12  Water Separator Level Switch  Switch to Ground 
17  Hydraulic Oil Level Switch  Switch to Ground 

Table 4
Contact Description for Connector C13 
No.  Function  Type 
Machine Can Data Link +  Input/Output 
Machine Can Data Link -  Input/Output 
Washer  Switch-to-Ground 
Wiper Int - 3  Switch-to-Ground 
Wiper Int - 6  Switch-to-Ground 
Wiper Low  Switch-to-Ground 

Table 5
Contact Description for Switch Panel Connector C2 
No.  Function  Type 
+B  +Battery 
GND  Ground 
Key Switch  Switch-to-Ground 
Fine Swing Solenoid  Output 
Heavy Lift Solenoid  Output 
12  Travel Alarm  Output 
15  Chassis/Cab Light Relay  Output 
16  Boom Light Relay  Output 
17  Fault Alarm  Output 
19  Alternator R Term  Input 

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