System Inputs

1. Key Power--Key power tells the ECA to read barometric pressure during Key ON/Engine OFF procedure for altitude compensation.
2. Profile Ignition Pick-Up (PIP)--Located within the distributor assembly, the profile ignition pick-up supplies crankshaft position and frequency information from the distributor to the ECA.
3. Throttle Position Sensor (TPS)--Mounted on the side of the carburetor assembly, the throttle position sensor provides the ECA with a signal proportional to the opening angle of the throttle plate.
4. Idle Tracking Switch (ITS)--The idle tracking switch is used to indicate when the DC motor idle speed control plunger contacts the throttle lever. When the ITS is open, idle speed will be controlled by the ECA. The ITS is integral with the DC idle speed control.
5. Engine Coolant Temperature (ECT) Sensor--Mounted on the heater pipe elbow, the engine coolant temperature sensor monitors engine coolant temperature and provides a corresponding signal to the ECA.
6. Exhaust Gas Oxygen (EGO) Sensor--Mounted in the exhaust manifold assembly, the exhaust gas oxygen sensor transmits a voltage signal to the ECA which indicates the oxygen level in the exhaust gasses.
7. Manifold Absolute Pressure (MAP) Sensor--The manifold absolute pressure sensor measures the intake manifold vacuum and provides a variable frequency signal to the ECA to indicate engine load. The MAP sensor also reads barometric pressure during Key ON/Engine OFF procedure, at wide open and part throttle modes. The MAP sensor is located on the right inner fender apron.
8. Neutral/Start Switch (NSS)--The Neutral/Start switch is used only on automatic transmission models and provides an input to the ECA to indicate whether or not the transmission is in Park or Neutral. This switch is located on the transmission assembly.
9. A/C Compressor Clutch (ACC) Signal--The ACC signal is used to indicate to the ECA when the air conditioning compressor is switched ON. This will allow the ECA to increase the engine idle speed to compensate for the increased engine load.
10. EGR Valve Position (EVP) Sensor--The EVP sensor signals the ECA with the correct EGR valve pintle (pivot pin) position.
11. Air Charge Temperature (ACT) Sensor--The air charge temperature sensor measures the temperature of the incoming air stream. The unit is located in front of the air cleaner. The ACT alters engine speed once the choke is let off. If the incoming air stream is cold, the ACT will signal the choke to release slowly. Below 55° F, the ACT will also dump thermactor air for catalyst protection.
12. Variable Voltage Choke--The variable voltage choke uses battery voltage duty cycle, which is based on the percentage of on-time to either slow or accelerate the choke action. It varies the percentage of time the choke is on. This system includes a single-pill choke cap, solid state power relay and an input from the ECA. At low ambient temperatures, the ECA will duty cycle voltage to the choke every 2-1/2 seconds that it is energized. As coolant and air temperature increase, or after the engine has been operating an extended period of time, the percentage of time with voltage to choke will increase to 100%. At a 50° F engine start-up, the choke will have a 100% duty cycle.