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B
Appendix B – Glossary
A/C:
Air Conditioner
A/D:
Analog to Digital
A/F:
Air/Fuel ratio. The proportion of air and fuel delivered to the cylinder for combustion. For
example, an A/F ratio of 14:1 denotes 14 times as much air as fuel in the mixture. A
typical ideal A/F ratio is 14.7:1.
ABS:
Anti-lock Brake System
AC Clutch Relay:
The PCM uses this relay to energize the A/C clutch, turning the A/C system on or off.
AC Pressure Sensor:
Measures air conditioning refrigerant pressure and sends a voltage signal to the PCM.
AC Pressure Switch:
A mechanical switch connected to the A/C refrigerant line. The switch is activated
(sending a signal to the PCM) when the A/C refrigerant pressure becomes too low.
Actuator:
Actuators such as relays, solenoids, and motors allow the PCM to control the operation
of vehicle systems.
Air Injection Reaction (AIR) System:
An emission control system operated by the PCM. During cold starts, an air pump injects
outside air into the exhaust manifold to help burn hot exhaust gases. This reduces pollu-
tion and speeds warm-up of oxygen sensors and catalytic converters. After the engine
is warm, the air will either be “dumped” back to the atmosphere (or into the air cleaner
assembly) or sent to the catalytic converter.
APP:
Acceleration Pedal Position (Sensor)
ASR:
Acceleration Slip Regulation
Bank 1:
The standard way of referring to the bank of cylinders containing cylinder #1. In-line
engines have only one bank of cylinders. Most commonly used to identify the location
of oxygen sensors. See O2S, Sensor 1, Sensor 2.
Bank 2:
The standard way of referring to the bank of cylinders opposite cylinder #1. Found on V-6,
V-8, V-10, etc. and horizontally opposed engines. Most commonly used to identify the
location of oxygen sensors. See O2S, Sensor 1,Sensor 2.
BARO:
Barometric Pressure Sensor. See MAP Sensor.
BBV:
Brake Boost Vacuum (Sensor)
BCM:
Body Control Module