HARNESS AS-ENGINE 4178827 - Caterpillar

Ground Wire Assembly For 621B, 623B, And 627B Tractors
First, cut the necessary wires to the lengths shown in the chart. Remove approximately 6 mm (.25") of insulation from the ends of the wires. Put a thin layer of solder over the strands at both ends of each wire.
Use only electrical-grade solder.Install the ends of each wire into the correct terminal as shown in Illustration 1. Use a crimping tool (Thomas and Betts WT-111-M Sta-Kon or equivalent) for an indented (pressed in) crimp. Then, make a good solder connection between the end of the wire and the terminal. Put some electrical tape around the connection.
Install the ground wire assembly on the gauges as shown in Illustration 2. Connect the male terminal to the female terminal on a wire which is yellow with a black stripe. This yellow and black wire comes out of the 2G7114 Tractor Cab Harness near the wires for the heat-start switch, low air warning switch, and converter-retarder temperature sender.
The second ground wire assembly is connected to a wire, which is yellow and has a black stripe, in the tractor engine wire harness (2G6821 for 621B and 623B Tractors, and 2G6823 for 627B Tractors). This wire comes out of the harness where it makes branches to the lights, scraper and engine. This location is near the left front of the engine. The other end of the ground wire is connected to the lower bolt in the front engine support, where the 9M9812 Ground Wire is fastened. The other end of the 9M9812 Ground Wire must be connected to the water pump.
Start the machine and check the operation of the gauges.
Illustration 1. Ground wire assembly dimensions and specifications for 621B, 623B, and 627B Tractors.
Illustration 2. Location of gauges for installation of ground wire assembly on 621B, 623B, and 627B Tractors.Ground Wire Assembly For 631D, 633D, 637D And 639D Tractors
First, cut the necessary number of wires to the lengths shown in the chart. Remove approximately 6 mm (.25") of the insulation from the ends of each wire. Put a thin layer of solder over strands at both ends of each wire.
Install each end of the wires into the correct terminal as shown in Illustration 3. Use a crimping tool (Thomas and Betts WT-111-M Sta-Kon or equivalent) for an indented (pressed in) crimp. Then, make a good solder connection between the end of the wire and the terminal. Put some electrical tape around the connection.
Connect the ground wire assembly to the gauges and to the mounting bolt for the low air warning horn as shown in Illustration 4.
Start the machine and check the gauges for correct operation.
Illustration 3. Ground wire assembly dimensions and specifications for 631D, 633D, 637D, and 639D Tractors.
Illustration 4. Location of gauges and low air pressure warning horn for installation of ground wire assembly on 631D, 633D, 637D, and 639D Tractors.