SEAL-V RING 8C3833 - Caterpillar

Switches
Switches provide information to the ECU. Switches are two state devices. The switches are either open or the switches are closed.Closed - The switch closes the circuit to ground or the switch closes the circuit to the battery.Open - the switch opens a circuit to the ECU input.Note: Damage to the wiring harness can create an open circuit. The ECM cannot distinguish between a damaged circuit and an open circuit. The ECM will read an open circuit for a switch to ground if the wiring harness has been damaged. A diagnostic code may not be initiated. A switch with this type of failure does not change state when the switch is toggled. The following three switches may have this type of failure:
Keyswitch
Shifter Select Switch
2WD/AWD Switch
Alternate max gear for the primary shifter
Alternate max gear for the secondary shifter
PTO no. 1 and PTO no. 2 enable
PTO no. 1 and PTO no. 2 increment/decrement
Quick to neutralKey Start Switch
Illustration 1 g00927534
When the key start switch is in the ON position, electrical power from the batteries is supplied to the electronic control modules.When the key start switch is in the START position and the conditions for starting the engine are satisfied, the start relay is energized.Oil Filter Bypass Pressure Switch
Illustration 2 g01252539
The pressure switch has a plunger inside the switch that closes the contacts with an acceptable pressure drop across the screen. The pressure switch grounds the signal circuit during normal operation. The pressure switch plunger moves in order to allow the pressure switch contacts to open. The pressure switch contacts open when pressure across the screen is greater than the specified value. If the screen is restricted the open pressure switch sends a signal to the ECU. The ECU informs the operator that the screen is restricted or dirty. The normal state of a pressure switch