3412, 3412C, and 3412E Generator Set Engines Caterpillar

Many of the procedures in this guide will direct you to a specific electrical connector. The connectors have a locking feature that holds the pins. The connectors have a locking feature that holds the sockets. The connectors are repairable without cutting the wires. Do not solder sockets and pins to the wires. Always crimp sockets and pins onto the wires with the 1U-5804 Crimp Tool.

Illustration 1	g00738352
Terminal connections The 8T-8729 Connector Pin and the 8T-8730 Connector Socket are designed to accept only one 16/18 AWG wire. Do not insert multiple wires of a smaller wire size. The 9W-0852 Connector Pin and the 9W-0844 Connector Socket are designed to accept only one 14 AWG wire. Do not insert multiple wires of a smaller wire size.

ECM Connector

Illustration 2	g01655753
(40-pin connector)

Service Tool Connector for Cat ET

Illustration 3	g01158896
(9-pin connector)

Harness Connectors

Illustration 4	g01317390

HD-10 Connectors

Ensure that the plug and the receptacle are aligned with the index marking. Rotate the plug until the plug slips into the receptacle. Rotate the coupling for one quarter of a turn. A click will be heard. Ensure that the two halves cannot be pulled apart. The acceptable range for the outside diameter of the wire is 2.50 to 3.75 mm (0.100 to 0.150 inch).

DT Connectors

The DT connectors use a wedge to lock the pins in place. Check that the seals are in place and check that the seals are properly seated. Check pins and sockets before the connectors are joined. Verify proper alignment and locations of pins and sockets in each connector. Check the locking tab for the DT connector for damage. Replace the connector if the tab is damaged. Ensure that the connector is properly locked. An audible click will be heard. Ensure that the two mating connectors can not be pulled apart. The acceptable range for the outside diameter of the wire is 2.20 to 3.68 mm (0.088 to 0.145 inch).