Equus 3123 - GM Code Reader (1982 - 1995) - Manual (Page 48)

4
4-9 GM
TDC – Top Dead Center.
THERMACTOR AIR CONTROL VALVE – Combines
function of a normally closed air bypass valve and an air
diverter valve in one integral valve.
THERMACTOR AIR SYSTEM – Efficiency of catalytic
converter is dependent upon temperature and chemical
makeup of exhaust gases. These requirements are met by the
thermactor air supply system.
THREE-WAY CATALYST – Combines 2 converters in 1
shell. Controls NOx, HC and CO. Also called dual catalytic
converter.
TIMING – Relationship between spark plug firing and piston
position.
TKS – Throttle Kicker Solenoid, when energized, supplies
manifold vacuum to throttle kicker actuator as directed by
computer to compensate for engine loads. Also called idle-up
system.
TOT – Transmission Oil Temperature sensor.
TP or TPS – Throttle Position Sensor or its circuit. Used to
signal computer the position of the throttle plates.
TPI – Tuned Port Injection, a type of MFI with intake tubes
designed to be tuned for performance. Most TPI engines are
also SFI.
TTS – Transmission Temperature Switch.
TVS – Temperature Vacuum Switch.
TVV – Thermal Vent Valve.
TWC – Three-Way Catalyst.
VACUUM – A term to describe a pressure that is less than
atmospheric pressure.
VACUUM ADVANCE – Advances ignition timing with
relation to engine load or computer signals.
VAF – Vane Air-Flow sensor or its circuit.
VAT – Vane Air-Flow Temperature sensor.
VATS – Vehicle Anti-theft System.
VCM - Vehicle Control Module.
VM – Vane Meter or air flow meter.
VSS – Vehicle Speed Sensor.
WOT – Wide Open Throttle or Wide Open Throttle switch.
WSS - Wheel Speed Sensor.