Hello, I have a Cat D3C Series III Hystat serial # 4KS00373 The park brake will not release after raising the park brake lever. After moving park brake lever up and down the brakes will release. When operating, the park brake will suddenly engage while moving. We replaced the switch #9x-4157 that is operated by the brake lever. This did not fix the problem and we are not sure if we reconnected it correctly. It has 4 wires, black, green, white, and pink. When we ground the one screw on the switch it will release the brake. Any help on the correct wiring of switch and park brake problem would be greatly appreciated.
Try getting the wiring in shape and the switch connected correctly as a first step. Check your messages. You have mail. The switch terminals are numbered 1 through 4, and are wired as shown below.
Thanks for the schematic. Going to check switch wiring today. There are no numbers on switch itself but will check continuity across terminals and wire accordingly
A bit more info. 306 GN comes from the key switch and should be live as soon as you turn the key to the ON position. 374 PK is an output of the neutral start/park brake switch that is used used to pull in the coil on the start relay. In turn that energizes 304 WH at the start relay which pulls in the starter solenoid. C907 WH goes to the service brake switch. When the contacts on both switches are closed that connects to ground and functions as the return wire for power at the park brake solenoid. 200 BK is a connection to ground.
Nige, We removed the screws from the switch and took a closer look and seen that the switch terminals are numbered. They are molded into the plastic and very hard to see. We wired it up using the schematics and park brake is functioning correcting. Thanks for your help!