ALTERNATOR GP-CHARGING 1264299 - Caterpillar

Position Sensor (Auxiliary Hydraulic Control)
Illustration 1 g01034219
Auxiliary control for the auxiliary hydraulics
Illustration 2 g01034147
Location of the auxiliary controlThe auxiliary hydraulic control is the thumb wheel on the work tool control that can be pressed upward or downward. The auxiliary hydraulic control tells the auxiliary hydraulic ECM that the operator wants to activate the auxiliary hydraulics. The auxiliary hydraulic control will allow the operator to control the amount of hydraulic oil flow that is sent to the auxiliary hydraulics.The auxiliary hydraulic control sends a proportional signal to the auxiliary hydraulic ECM. The signal is a pulse width modulated signal (PWM) that is generated at a frequency between 500 Hz 80 Hz. When the auxiliary hydraulic control is in the neutral position, a duty cycle of 50% 3% is seen by the ECM. When the auxiliary hydraulic control is pressed up or down, the duty cycle will vary from 50% to a minimum of 20% in the A2 position and from 50% to a maximum of 80% in the A1 position.The auxiliary hydraulic ECM receives the proportional signal on pin 53 of the ECM. The auxiliary hydraulic ECM will then send a proportional signal to the corresponding modulated valve (auxiliary) (A1 or A2).The auxiliary hydraulic ECM monitors the auxiliary control for duty cycles that are erratic, out of range or an abnormal frequency. A diagnostic code will then be set and the auxiliary hydraulics will not function.