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I am not familiar with all the initials that every one uses.
ALDL = Assembly Line Diagnostic Link. It's the connector just above your right knee that the scan tool connects to. The connector changed over the years, so pins A & B might not be the right ones for your setup. See these links:
ECM = Engine Control Module (also Electronic Control Module). It's the car's "computer". Later years called it a PCM for Powertrain Control Module.
CTS = Coolant Temperature Sensor. It tells the ECM what the temperature of the coolant is. The ECM uses that information to determine spark advance, fuel injector pulse width and idle speed (actually a bunch of other stuff too). The ECM turns on the radiator fans based on the coolant temperature.
Last edited by Cliff Harris; May 20, 2013 at 11:14 PM.