CONTROL GP-ELECTRONIC 2115558 - Caterpillar

Switches provide information (input) to the transmission electronic control module (ECM). Switches are two state devices. The two states are in the following list:Closed - The switch closes the circuit to ground or the switch closes to the + battery.Open - The Switch opens a circuit to the control input.Downshift Switch
Illustration 1 g00614333
Downshift SwitchIf you press the downshift switch, the ECM signals the transmission to downshift one gear. The downshift switch has two input connections to the control: downshift N/C at contact 23 and downshift N/O at contact 22. When the operator presses the downshift switch, the downshift N/C circuit is open and the downshift N/O circuit is closed to ground. When the switch is not activated, the downshift N/C is closed to ground and the downshift N/O is open.Note: A double-pole switch is used for diagnostic purposes. If the two poles are in the same state, the ECM notes a circuit failure. This fault is then shown on the diagnostic indicator. See Testing and Adjusting, "Using the Diagnostic Indicator to Determine Diagnostic Codes".AUTO/MANUAL Switch
Illustration 2 g00614455
AUTO/MANUAL SwitchThe AUTO/MANUAL switch selects the operating mode of the ECM. The AUTO/MANUAL switch has two input connections to the control. When the operator selects AUTO, the N/C input is closed to ground and the N/O circuit is open. When the operator selects MANUAL, the N/O input is closed to ground and the N/C circuit is open.Shift Lever Switches
Illustration 3 g00614489
Shift Lever SwitchThe shift lever switches select a gear input and a directional input. This is accomplished by closing the input to battery power or to ground.Neutralizer Switch
Illustration 4 g00614492
Neutralizer SwitchThe neutralizer switch is a two-position limit switch. The neutralizer switch is located inside the brake pedal assembly. When the brake pedal is depressed, the switch is open. When the line opens, the shift lever cannot close the direction of the solenoids to the battery voltage. This neutralizes the transmission. When the brake pedal is released, the switch (N/C) is closed to the battery. This allows the ECM to open the directional solenoids.Neutralizer Override Switch
Illustration 5 g00614494
Neutralizer Override SwitchThe neutralizer override switch is used in order to disable the neutralizer switch. When the neutralizer override switch is activated, the neutralizer input line is then closed to battery voltage. This happens even if the neutralizer switch is applied. The neutralizer override switch is used to disable the neutralizer switch when neutralizing the transmission during braking is not desired.