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. The ECM then 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 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 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.
| Contact Description for Connector J1 (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 |
| 8 | CAN 2 + : Machine Data Link | CAN 2 + |
| 9 | CAN 1 + : J1939 | CAN 1 + |
| 12 | Boom Up Control Pilot Pressure Sensor | Analog Active Input |
| 13 | Right Travel Pressure Sensor | Analog Active Input |
| 14 | Left Travel Pressure Sensor | Analog Active Input |
| 15 | 5V Supply | 5V Supply 1 |
| 16 | Implement Pressure Sensor | Analog Active Input |
| 17 | Atmosphere Pressure Sensor | Analog Active Input |
| 18 | Fuel Filter Plugged Sensor | Analog Active Input |
| 22 | Hydraulic Lock Solenoid | PRV 1 |
| 23 | Swing Brake Solenoid | PRV 2 |
| 24 | Travel Speed Solenoid | PRV 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 | Engine Oil Pressure Sensor | Analog Active Input |
| 34 | Analog & PWM Return 1 | Analog & PWM Return 1 |
| 35 | Hydraulic Oil Temperature Sensor | Analog Passive Input |
| 38 | Analog & PWM Return 2 | Analog & PWM Return 2 |
| 39 | Engine Speed Command | Low Sink |
| 41 | Key Switch | Key Switch |
| 43 | Straight Travel Solenoid | PRV 5 |
| 49 | Switch To Ground Return 1 | Switch To Ground Return 1 |
| 52 | Foot Switch | Switch To Ground 6 |
| 54 | Pump 1 Pressure Sensor | PWM Input 1 |
| 55 | Pump 2 Pressure Sensor | PWM Input 2 |
| 58 | Hydraulic Lock Cancel Switch | Switch To Battery 1 |
| 58 | Hydraulic Lock Cancel Switch | Switch To Battery 1 |
| 60 | Start Detection | Input\Output |
| 61 | Neutral Start Relay | PRV 6 |
| 62 | Shutoff Solenoid | PRV 7 |
| 73 | Engine Speed Command Read | PWM Input 5 |
| 78 | Engine Speed Sensor | VR+ |
| 79 | Flow Limit Press PRV | PRV 8 |
| 80 | 2 Pump Flow Combine Solenoid | PRV 9 |
| 81 | PS Pressure PRV | PRV 10 |
| (1) | Contacts that are not listed are not used. |
| Contact Description for Connector J2 (1) | ||
|---|---|---|
| No. | Function | Type |
| 88 | Attachment Stem 3 Retract Assist Solenoid | PRV 17 |
| 89 | Attachment Stem 3 Extend Assist Solenoid | PRV 18 |
| 96 | Attachment Stem 2 Retract Assist Solenoid | PRV15 |
| 97 | Attachment Stem 2 Extend Assist Solenoid | PRV 16 |
| 104 | Attachment Stem 1 Retract Assist Solenoid | PRV 13 |
| 105 | Attachment Stem 1 Extend Assist Solenoid | PRV 14 |
| 106 | Attachment Stem 1 Status Sensor | Analog Active Input 9 |
| 108 | Attachment Stem 3 Status Sensor | Analog Active Input 11 |
| 109 | Attachment Stem 4 Status Sensor | Analog Active Input 12 |
| 112 | Variable Relief 1 Solenoid | PRV 11 |
| 113 | Variable Relief 2 Solenoid | PRV 12 |
| 114 | PRV 17–18 Return | PRV 17–18 Return |
| 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. |
| Contact Description for Connector F-C301 | ||
|---|---|---|
| No. | Function | Type |
| 2 | Fuel Level Sensor | Input |
| 3 | Hydraulic Oil Temperature Sensor | Input |
| 4 | Analog Return | Analog Return |
| 7 | Air Filter Plugged Switch | Switch to Ground |
| 8 | Capsule Filter Plugged Switch | Switch to Ground |
| 10 | ATT Hydraulic Oil Filter Switch | Switch to Ground |
| 11 | OLWD Alarm Cancel Switch | Switch to Ground |
| 12 | Water Separator Level Switch | Switch to Ground |
| Contact Description for Connector F-C302 | ||
|---|---|---|
| No. | Function | Type |
| 1 | Machine CAN Data Link + | CAN + |
| 2 | Machine CAN Data Link + | CAN - |
| 4 | Washer | LCSD |
| 5 | Wiper Int - 3 | LCSD |
| 6 | Wiper Int - 6 | LCSD |
| 7 | Wiper Low | LCSD |
| 10 | A/C Clutch Solenoid | Switch-to-Battery |
| Contact Description for Switch Panel Connector F-C303 | ||
|---|---|---|
| No. | Function | Type |
| 1 | +B | +Battery |
| 2 | GND | Ground |
| 3 | Key Switch | Key Switch |
| 4 | Fault Alarm | On/Off |
| 5 | Electric Lifting Pump Relay | On/Off |
| 7 | Heavy Lift Solenoid | On/Off |
| 8 | Hammer Return To Tank Solenoid | On/Off |
| 10 | B+ | Unswitched Battery |
| 11 | ON/OFF Driver | |
| 12 | Travel Alarm | On/Off |
| 15 | Chassis/Cab Lamp Relay | Relay |
| 16 | Boom Lamp Relay | Relay |
| 19 | Alternator R Term | Frequency Input |