725C, 725C2, 730C, 730C Ejector, 730C2, 730C2 EJ, 735C, 740 Ejector, 740C Ejector, 745 and 745C Articulated Trucks Cat® Production Measurement Application Caterpillar

Payload ECM decisions are based on input data information and programming parameters that have been flashed to the ECM memory. After an 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 a 12-pin connector.

Note: ECMs are not serviceable. If the ECM is damaged, the ECM must be replaced. See the Troubleshooting, "ECM - Replace" story in this manual before replacing an ECM.

Input/Output

Communication between the Payload ECM, the other ECMs on the machine, the display devices, and the input devices is conducted over the data link circuits. The data link circuits are bidirectional, allowing the ECM to send and receive information.

The Payload ECM supports two types of data link systems:

• CAN 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.

Communication between the Payload ECM and the other ECMs on the machine is conducted over the J1939 data link circuit.

Inputs

The payload system uses CAN bus type sensors. The Payload ECM receives payload information over a two-wire CAN data link.

Outputs

The Payload ECM provides payload information to the CMPD over a two wire J1939 data link.

ECM Contacts

The following tables list the connections for the Payload ECM.

Table 1

Payload ECM Contact Description
No.	Function	Type
1	CAN L Sensor	CAN Bus Sensors
2	CAN H Sensor	CAN Bus Sensors
3	Sensor Ground	Ground
4	Sensor Power	Power
5
6
7	Power (Key Switch)	Switch to Power
8	Power +	Power
9	Power -	Ground
10
11	J1939 L Data Link (System)	Data Link
12	J1939 H Data Link (System)	Data Link