DIFFERENTIAL GP 3551142 - Caterpillar

The CAN data link is used for communication between the following modules: engine's Electronic Control Module (ECM), customer devices and various display modules. Two 120 Ohm terminating resistors must be installed in the wiring harness in order for the CAN data link to function properly.
Illustration 1 g01199117
Typical example
Illustration 2 g01241421
P1 ECM connector
(P1-34) CAN data link −
(P1-42) Shield for the CAN data link
(P1-50) CAN data link +
Illustration 3 g01241422
Service tool connector
(Terminal C) Shield for the CAN data link
(Terminal F) CAN data link +
(Terminal G) CAN data link −
Illustration 4 g01241424
Customer connector
(Terminal BT) Shield for the CAN data link
(Terminal BV) CAN data link +
(Terminal BU) CAN data link −
Illustration 5 g01234146
Location of ECM connectors
Test Step 1. Inspect Electrical Connectors and Wiring
Turn the Engine Control Switch (ECS) to the OFF/RESET position.
Turn the battery disconnect switch to the OFF position.
Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The connectors and wiring are OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are not OK.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.STOPTest Step 2. Verify the Proper Installation of the Terminating Resistors
Verify that the terminating resistors are installed on the ends of the data link.
Disconnect J1/P1 ECM connector and measure the resistance between P1-50 (CAN