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 Caterpillar before replacing the ECM. Replace the ECM only after all the other possible causes of a particular problem have been investigated.
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
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.
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.
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.
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 Connector J1 Contact Descriptions(1) | ||
|---|---|---|
| No. | Function | Type |
| 1 | Ground | Ground |
| 2 | PRV 8-10 Return | PRV Return |
| 3 | PRV 4-7 Return | PRV Return |
| 4 | + Battery | Battery (+) |
| 5 | PRV 1-3 Return | PRV Return |
| 6 | Straight Travel Pressure Sensor | Analog Active Input |
| 7 | CAN 4 + : Control Data Link | CAN 3 + |
| 8 | CAN 2 + : Machine Data Link | CAN 2 + |
| 9 | CAN 1 + : J1939 | CAN 1 + |
| 10 | Location Code 1 | Switch To Ground 1 |
| 12 | Boom Up Control Pilot Pressure Sensor | Analog Active Input |
| 13 | Right Travel Pressure Sensor | Analog Active Input |
| 14 | Standard Implement Pilot Pressure Sensor/Left Travel Pressure Sensor | Analog Active Input |
| 15 | 5V Supply | 5V Supply 1 |
| 16 | Joystick Pilot Pressure Sensor/Implement Pressure Sensor | Analog Active Input |
| 17 | Boom Down Control Pressure Sensor | Analog Active Input |
| 18 | Stick In Control Pressure Sensor | Analog Active Input |
| 20 | 8V Supply | 8V Supply 1 |
| 22 | Hydraulic Lock Solenoid | PRV 1 |
| 23 | Swing Brake Solenoid | PRV 2 |
| 24 | Travel Speed Solenoid | PRV 3 |
| 25 | Bucket In Control Pressure Sensor | Analog Active Input |
| 26 | CAN 4 - : Control Data Link | CAN 3 - |
| 27 | 2 - : Machine Data Link | CAN 2 - |
| 28 | CAN 1 - : J1939 | CAN 1 - |
| 29 | One Touch Low Idle Switch | Switch To Ground 8 |
| 32 | Stick Out Control Pressure Sensor | Analog Active Input |
| 33 | Swing Control Pressure Sensor | Analog Active Input |
| 34 | Analog & PWM Return 1 | Analog & PWM Return 1 |
| 38 | Analog & PWM Return 2 | Analog & PWM Return 2 |
| 41 | Key Switch | Key Switch |
| 42 | Boom Regeneration PRV | PRV 4 |
| 43 | Straight Travel Solenoid | PRV 5 |
| 49 | Switch To Ground Return 1 | Switch To Ground Return 1 |
| 50 | Location Code Enable/Disable | Switch To Ground 4 |
| 54 | Pump 1 Pressure Sensor | PWM Input 1 |
| 55 | Pump 2 Pressure Sensor | PWM Input 2 |
| 56 | NFC 1 Pressure Sensor | PWM Input 3 |
| 57 | NFC 2 Pressure Sensor | PWM Input 4 |
| 58 | Hydraulic Lock Cancel Switch | Switch To Battery 1 |
| 59 | CTWT Removal Switch | Switch To Battery 2 |
| 61 | NFC 1 Solenoid/ESP Pump 1 Solenoid | PRV 6 |
| 62 | NFC 2 Solenoid/ESP Pump 2 Solenoid | PRV 7 |
| 68 | Switch To Ground Return 2 | Switch To Ground Return 2 |
| 69 | Left Joystick Switch 1 (Upper) | Switch To Ground 11 |
| 70 | Right Joystick Switch 1 (Upper) | Switch To Ground 12 |
| 71 | Left Joystick Switch 2 (Fore) | Switch To Ground 13 |
| 72 | Right Joystick Switch 2 (Fore)/Smart Boom Cancel | Switch To Ground 14 |
| 73 | Boom Cylinder Head Pressure Sensor | PWM Input 5 |
| 74 | Boom Cylinder Rod Pressure Sensor | PWM Input 6 |
| 75 | Thumbwheel - LH | PWM Input 7 |
| 76 | Thumbwheel - RH | PWM Input 8 |
| 77 | Bucket Cylinder Head Pressure Sensor | PWM Input 16 |
| 80 | Boom Down Solenoid | PRV 9 |
| 81 | Power Shift Solenoid | PRV 10 |
| (1) | Contacts that are not listed are not used. |
| Machine ECM Connector J2 Contact Descriptions(1) | ||
|---|---|---|
| No. | Function | Type |
| 86 | Attachment Stem 4 Status | Switch To Ground 18 |
| 87 | Analog & PWM Return 4 | Analog & PWM Return |
| 88 | Boom Up Limit Solenoid For Crane/Snubber Solenoid For 325F | PRV 17 |
| 89 | Bucket Out Limit Solenoid | PRV 18 |
| 90 | CAN 3 + : J1939 for CGC | CAN 4 + |
| 91 | CAN 3 - : J1939 for CGC | CAN 4 - |
| 92 | 8V Supply | 8V Supply 2 |
| 93 | Sensor Supply Return/Switch To Ground Return 3 | Sensor Supply Return/Switch To Ground Return 3 |
| 98 | Boom Angle Sensor | PWM Input 11 |
| 99 | Pump 1 Displacement Sensor | PWM Input 12 |
| 100 | Analog & PWM Return 3 | Analog & PWM Return 3 |
| 101 | 5V Supply | 5V Supply 2 |
| 102 | Pump 2 Displacement Sensor | PWM Input 13 |
| 106 | Auxiliary Pedal 2 Control Pressure Sensor | Analog Active Input 9 |
| 107 | Auxiliary Pedal 1 Control Pressure Sensor | Analog Active Input 10 |
| 110 | Bucket Position Sensor | PWM Input 9 |
| 111 | Stick Angle Sensor | PWM Input 10 |
| 112 | Variable Relief 1 Solenoid | PRV 11 |
| 113 | Variable Relief 2 Solenoid | PRV 12 |
| 117 | PRV 13-14 Return | PRV 13-14 Return |
| 118 | PRV 15-16 Return | PRV 15-16 Return |
| 119 | PRV 11-12 Return | PRV 11-12 Return |
| (1) | Contacts that are not listed are not used. |
| Implement Control ECM Connector J1 Contact Descriptions(1) | ||
|---|---|---|
| No. | Function | Type |
| 1 | Ground | Ground |
| 2 | PRV 8-10 Return | PRV 8-10 Return |
| 3 | PRV 4-7 Return | PRV 4-7 Return |
| 4 | + Battery | + Battery |
| 5 | PRV 1-3 Return | PRV 1-3 Return |
| 7 | CAN 4 + : Control Data Link | CAN 3 + |
| 9 | CAN 1 + : J1939 | CAN 1 + |
| 11 | Location Code 2 | Switch To Ground 1 |
| 20 | 8V Supply | 8V Supply 1 |
| 23 | Attachment Stem 3 Retract Solenoid | PRV 2 |
| 24 | Attachment Stem 3 Extend Solenoid | PRV 3 |
| 26 | CAN 4 - : Control Data Link | CAN 3 - |
| 28 | CAN 1 - : J1939 | CAN 1 - |
| 38 | Analog & PWM Return 2 | Analog & PWM Return 2 |
| 41 | Key Switch | Key Switch |
| 42 | Attachment Stem 2 Retract Solenoid | PRV 4 |
| 43 | Attachment Stem 2 Extend Solenoid | PRV 5 |
| 49 | Switch To Ground Return 1 | Switch To Ground Return 1 |
| 50 | Location Code Enable/Disable | Switch To Ground 4 |
| 51 | Foot Switch | Switch To Ground 5 |
| 54 | Squeeze Sensor | PWM Input 1 |
| 55 | Auxiliary Right Pedal | PWM Input 2 |
| 56 | Auxiliary Left Pedal | PWM Input 3 |
| 61 | Attachment Stem 1 Retract Solenoid | PRV 6 |
| 62 | Attachment Stem 1 Extend Solenoid | PRV 7 |
| 79 | Attachment Stem 4 Retract Solenoid | PRV 8 |
| 80 | Attachment Stem 4 Extend Solenoid | PRV 9 |
| 81 | Stick In Solenoid | PRV 10 |
| (1) | Contacts that are not listed are not used. |
| |
| Illustration 1 | g02655338 |
|
Underside of switch panel | |
| Contact Description for Connector J1 | ||
|---|---|---|
| No. | Function | Type |
| 2 | Fuel Level Sensor | Analog Input |
| 3 | Hydraulic Oil Temperature Sensor | Analog Input |
| 4 | Analog Return | Analog Return |
| 5 | A / C Unit | Switch to Ground |
| 7 | Refuel Start Switch | Switch to Ground |
| 8 | Capsule Filter Plugged Switch | Switch to Ground |
| 9 | Fine Swing Switch | Switch to Ground |
| 11 | OLWD Warning Alarm Enable Switch | Switch to Ground |
| 13 | Boom Low Press Relief Enable Switch | Switch to Ground |
| Contact Description for Connector J2 | ||
|---|---|---|
| No. | Function | Type |
| 1 | Machine CAN Data Link + | CAN + |
| 2 | Machine CAN Data Link - | CAN - |
| 4 | Washer | Switch to Ground |
| 5 | Wiper Int - 3 | Switch to Ground |
| 6 | Wiper Int - 6 | Switch to Ground |
| 7 | Wiper Low | Switch to Ground |
| 11 | Smart Boom Down Switch | Switch-to-Ground |
| 12 | Smart Boom Up/Down Switch | Switch-to-Ground |
| Contact Description for Switch Panel Connector J3 | ||
|---|---|---|
| No. | Function | Type |
| 1 | +B | +Battery |
| 2 | GND | Ground |
| 3 | Key Switch | Key Switch |
| 4 | Swing Priority Solenoid | On/Off |
| 5 | Quick Coupler Bypass Cut Solenoid | On/Off |
| 6 | Fine Swing Solenoid | On/Off |
| 7 | Heavy Lift Solenoid | On/Off |
| 8 | Caution Lamp for Crane | On/Off |
| 9 | Boom Down Electric Check Solenoid for STBM (EC1) | On/Off |
| 11 | Boom Up Electric Check Solenoid for STBM (EC2) | On/Off |
| 12 | Travel Alarm | On/Off |
| 13 | Quick Coupler Uncoupling Solenoid | On/Off |
| 14 | Boom Low Press Relief Enable Solenoid | On/Off |
| 15 | Cab Lamp Relay | Relay |
| 16 | Boom Lamp Relay | Relay |
| 17 | Fault Alarm | Relay |
| 19 | Alternator R Term | Freq In - R Term |
| 20 | Quick Coupler Unlock Switch | Switch-to-Ground |