PIN 8X0659 - Caterpillar

Inputs
The machine has several different types of input devices. The ECM receives machine status information from the input devices and determines the correct output action that is needed to control machine operations based on memory and software parameters. The machine utilizes the following types of inputs: switch type and sensor type.Switches provide signals to the switch inputs of the ECM. The possible outputs of a switch are listed: an open signal, a grounded signal and + battery signal.Sensors provide an electrical signal to the ECM that constantly changes. The sensor input to the ECM can be one of several different types of electrical signals such as: pulse width modulated (PWM) signals, voltage signals, and frequency input signals. Each possible input to the ECM is listed in the tables for the 70-pin connectors.Inputs provide information to the ECM in the form of sensors or switches.Sensors
Sensors provide information to the ECM about the intent of the operator or changing conditions. The sensor signal changes proportionally to the changing of operator input or changing conditions. The following types of sensor signals are used by the ECM.Frequency - The sensor produces a signal and the frequency (Hz) varies as the condition changes.Pulse width modulated - The sensor produces a signal. The duty cycle of the signal varies as the condition changes. The frequency of this signal is constant.Analog - The ECM measures the voltage that is associated to a specific condition of the control.Operator Temperature Control
Illustration 2 g06225165The operator temperature control sensor monitors the signal from the temperature control knob on the HVAC panel. This knob sets the operators desired temperature in automatic mode and adjusts the water valve in manual mode. In either mode, the ECM receives a pulse width modulated signal from the knob and HVAC panel that corresponds to a desired temperature or water valve position. The duty cycle is proportional to the position of the knob.Switches
Switches provide an open signal, a ground signal, or a +battery signal to the inputs of the ECM. Switches are open or closed.
When a switch is open, no signal is provided to the corresponding input of the ECM. The “no signal” condition is also called “floating”.
When a switch is closed, a ground signal or a +battery signal is provided to the corresponding input of the ECM.Air Conditioning Mode Switch
Illustration 3 g06225171The air conditioning mode switch is a two pole switch. The switch has two positions that control the operation of the air conditioning. In the automatic position the ECM controls the operation of the air conditioning to maintain a specified cab temperature. In the manual position, the air conditioning is manually engaged. The ECM has two contacts that pertain to this switch, one signals the ECM the switch is automatic mode, the other signals the ECM the switch is in manual mode. These contacts will float to a high voltage state unless the switch is closed to that contact. When the switch closes to a contact, the contact is pulled to a low or ground