Engine Control; Ptis (Input Signals) - Toyota 1993 MR2 Wiring Diagrams

ENGINE CONTROL (3S–GTE)
SYSTEM OUTLINE
THE ENGINE CONTROL SYSTEM UTILIZES A MICROCOMPUTER AND MAINTAINS OVERALL CONTROL OF THE ENGINE. ETC. AN
OUTLINE OF ENGINE CONTROL IS GIVEN HERE.

1. PTIS (INPUT SIGNALS)

(1) WATER TEMP. SIGNAL SYSTEM
THE ECTS (WATER TEMP. SENSOR) DETECTS THE ENGINE COOLANT TEMP. AND HAS A BUILT–IN THERMISTOR WITH A
RESISTANCE WHICH VARIES ACCORDING TO THE WATER TEMP. THUS THE WATER TEMP. IS INPUT IN THE FORM OF A
CONTROL SIGNAL TO TERMINAL THW OF THE PCME (ECU).
(2) INTAKE AIR TEMP. SIGNAL SYSTEM
THE IATS (INTAKE AIR TEMP. SENSOR) IS INSTALLED INSIDE THE AFS (AIR FLOW METER) AND DETECTS THE INTAKE AIR TEMP.,
WHICH IS INPUT AS A CONTROL SIGNAL TO TERMINAL THA OF THE PCME (ECU).
(3) OXYGEN DENSITY SIGNAL SYSTEM
THE OXYGEN DENSITY IN THE EXHAUST EMISSIONS IS DETECTED AND INPUT AS A CONTROL SIGNAL TO TERMINAL OX OF
THE PCME (ECU). TO MAINTAIN STABLE DETECTION PERFORMANCE BY THE HOZS (OXYGEN SENSOR), A HEATER IS USED
FOR WARMING THE SENSOR. THE HEATER IS ALSO CONTROLLED BY THE PCME (ECU) (HT).
(4) CRANKSHAFT POSITION SIGNAL SYSTEM
CRANKSHAFT POSITION AND ENGINE SPEED IS DETECTED BY THE PICK–UP COIL INSTALLED INSIDE THE DISTRIBUTOR.
CRANKSHAFT POSITION IS INPUT AS A CONTROL SIGNAL TO TERMINAL G1 AND G2 OF THE PCME (ECU), AND ENGINE SPEED
SIGNAL IS INPUT TO TERMINAL NE+.
(5) THROTTLE POSITION SIGNAL SYSTEM
THE THROTTLE POSITION SENSOR DETECTS THE THROTTLE VALVE OPENING ANGLE, WHICH IS INPUT AS A CONTROL
SIGNAL TO TERMINAL VTA OF THE PCME (ECU), OR WHEN THE VALVE IS FULLY CLOSED, TO TERMINAL IDL.
(6) VEHICLE SPEED SIGNAL SYSTEM
THE SPEED METER INSIDE THE COMBINATION METER SENDS A VEHICLE SPEED SIGNAL TO TERMINAL SPD OF THE PCME
(ECU) AS A CONTROL SIGNAL.
(7) ACS (A/C SW) SIGNAL SYSTEM
THE OPERATING VOLTAGE OF THE A/C MAGNETIC CLUTCH IS DETECTED AND INPUT IN THE FORM OF A CONTROL SIGNAL TO
TERMINAL AC OF THE PCME (ECU).
(8) BATTERY SIGNAL SYSTEM
VOLTAGE IS CONSTANTLY APPLIED TO TERMINAL BATT OF THE PCME (ECU). WHEN THE IGNITION SW IS TURNED TO ON,
VOLTAGE FOR PCME (ECU) OPERATION IS APPLIED VIA THE EFI MAIN RELAY TO TERMINALS +B AND +B1 OF THE ECU.
(9) INTAKE AIR VOLUME SIGNAL SYSTEM
INTAKE AIR VOLUME IS DETECTED BY THE POTENTIOMETER INSTALLED INSIDE THE AIR FLOW METER AND IS INPUT AS A
CONTROL SIGNAL TO TERMINAL VS OF THE PCME (ECU).
(10) STOP LIGHT SW SIGNAL SYSTEM
THE STOP LIGHT SW IS USED TO DETECT WHETHER OR NOT THE VEHICLE IS BRAKING AND THE INFORMATION IS INPUT AS A
CONTROL SIGNAL TO TERMINAL STP OF THE PCME (ECU).
(11) STA SIGNAL SYSTEM
TO CONFIRM THAT THE ENGINE IS CRANKING, THE VOLTAGE APPLIED TO THE STARTER MOTOR DURING CRANKING IS
DETECTED AND IS INPUT AS A CONTROL SIGNAL TO TERMINAL STA OF THE PCME (ECU).
(12) ENGINE KNOCK SIGNAL SYSTEM
ENGINE KNOCKING IS DETECTED BY THE KNOCK SENSOR AND INPUT AS A CONTROL SIGNAL TO TERMINAL KNK OF THE
PCME (ECU).
(13) ELECTRICAL LOAD SIGNAL SYSTEM
THE SIGNAL WHEN SYSTEMS SUCH AS THE REAR WINDOW DEFOGGER, HEADLIGHTS, ECT. WHICH CAUSE A HIGH
ELECTRICAL BURDEN ARE ON IS INPUT TO TERMINAL ELS AS A CONTROL SIGNAL.
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