SUPPORT AS 2057788 - Caterpillar

Illustration 13 g02573876
Input circuits of the "Secondary Steering Test " and "Parking Brake" switches
The "Parking Brake" switch and the "Secondary Steering Test" switch each provide a switch-to-ground input to the "Transmission/Chassis ECM". The switches are two-pole, double-throw rocker switches. The switches are located on the right-hand console in the cab.One pole on each of the switches is used to provide the two inputs to the ECM to indicate the switch status. During normal operation, one of the inputs is open and the other input is closed to ground. The other switch pole is either not used or is used for switch backlighting.If the ECM detects that both of the switch inputs are grounded at the same time or both of the switch inputs are open at the same time, the ECM will activate a diagnostic code for the involved switch.For the operation of the "Secondary Steering Test" switch, when the ECM detects a ground condition in the "Normally Closed" switch input circuit, the ECM will activate the steering test mode when the required machine conditions are correct. When the ECM detects a ground condition in the "Normally Open" switch input circuit, the ECM will deactivate the secondary steering test mode.For the operation of the parking brake switch, when the ECM detects a ground condition in the "Normally Closed" input circuit of the switch, the ECM will deactivate the parking brake solenoid to engage the parking brake, if the machine conditions are correct. When the ECM detects a ground condition in the "Normally Open" input circuit of the switch, the ECM will energize the parking brake solenoid to disengage the parking brake if the machine conditions are correct. In order for the switch to be disengaged, the machine:
Transmission Shift lever must be in neutral.
The Steering must be aligned.Note: Refer to the Parking Brake System section of this manual if the parking brake does not disengage when the parking brake switch is moved to the OFF position.Brake Pedal Switch
Illustration 14 g02574398
Input circuit of the "Brake pedal" switch
The brake pedal limit switch provides a switch-to-ground input to the "Transmission/Chassis ECM". The brake pedal switch provides one input to the ECM. The second input activates the machine brake lights.The ECM monitors the input from the switch of the brake pedal to detect if the brake pedal is depressed or not .Brake System Monitoring
The Brake Control System is controled by the Transmission/Chassis ECM. The Brake Control System uses inputs and outputs to provide the operator information on the hydraulic brake pressure via the Cat Monitoring System. The Brake Control System receives signals from the pressure sensors for the tractor and the scraper. Differential Lock Switch
The differential lock function provides improvements to machine traction by sending power to both wheels of the tractor through a jaw clutch. The operator engages the differential lock by depressing an actuation switch on the floor of the operator station. When the differential lock is engaged, both wheels rotate at the same speed. Power is divided proportionally by the traction of