Equus 3123 - GM Code Reader (1982 - 1995) - Manual (Page 47)

Glossary
GM 4-8
QUAD-DRIVER (QDM) – Computer chip, in the PCM,
capable of operating four separate outputs. Some have digital
and some have pulse width modulated outputs.
RAP – Retained Accessory Power.
RELAY – Switching device operated by a low current circuit,
which controls opening and closing of another higher current
circuit.
RELIEF VALVE – Pressure limiting valve located in exhaust
chamber of thermactor air pump. Relieves part of exhaust
airflow if pressure exceeds a calibrated value.
RICH MIXTURE – Air/fuel mixture that has more fuel than
can burn completely, 1 part fuel to 14 or less parts air.
SAW – Spark Advance Word, and also Spark Angle Word.
SCC – Spark Control Computer.
SES – Service Engine Soon light.
SEFI, SFI – Sequential Fuel Injection, type of MFI with
injectors pulsed individually based on engine firing order.
SIG RTN – Signal Return circuit for all sensors except HEGO.
SIL – Shift Indicator Light. Indicates to driver optimum time
to shift gears.
SIR – Supplemental Inflatable Restraint (SIR) system; air
bag.
SIS – Solenoid Idle Stop.
SOLENOID – Wire coil with a movable core which changes
position by means of electromagnetism when current flows
through the coil.
SPARK RETARD SOLENOID – Output device that receives
an output signal to bleed distributor’s vacuum advance when
spark knock occurs.
SSI – Solid State Ignition system.
T.V. – Throttle Valve.
TAB – Thermactor Air Bypass solenoid.
TACH INPUT – Engine rpm signal sent to computer from
ignition coil primary circuit.
TAD – Thermactor Air Diverter solenoid.
TBI – Throttle Body Injection (Fuel).
TCC – Torque Converter Clutch.
TCP – Temperature Compensating Pump.