Port TOYOTA CAMRY 1994 XV10 / 4.G Wiring Diagrams Workshop Manual

15
ABBREVIATIONS
ABBREVIATIONS
The following abbreviations are used in this manual.
ABS = Anti±Lock Brake System
ACIS = Acoustic Control Induction System
A/C = Air Conditioning
A/T = Automatic Transmission
COMB. = Combination
C/P = Coupe
ECU = Electronic Control Unit
EFI = Electronic Fuel Injection
EGR = Exhaust Gas Recirculation
ESA = Electronic Spark Advance
Ex. = Except
FL = Fusible Link
IAC = Idle Air Control
ISC = Idle Speed Control
J/B = Junction Block
LH = Left-Hand
MFI = Multiport Fuel Injection
M/T = Manual Transmission
O/D = Overdrive
R/B = Relay Block
RH = Right±Hand
RPM = Engine Speed
S/D = Sedan
SFI = Sequential Multiport Fuel Injection
SRS = Supplemental Restraint System
SW = Switch
TEMP. = Temperature
VSV = Vacuum Switching Valve
W/G = Wagon
w/ = With
w/o = Without
*The titles given inside the components are the names of the terminals (terminal codes) and
are not treated as being abbreviations.

79
2. CONTROL SYSTEM
*SFI (SEQUENTIAL MULTIPORT FUEL INJECTION) (EFI (ELECTRONIC FUEL INJECTION) SYSTEM
THE EFI SYSTEM MONITORS THE ENGINE CONDITION THROUGH THE SIGNALS INPUT FROM EACH SENSOR (INPUT SIGNALS
FROM (1) TO (12) ETC.). THE BEST FUEL INJECTION VOLUME IS DECIDED BASED ON THIS DATA AND THE PROGRAM MEMORIZED
BY THE ENGINE CONTROL MODULE (ECU), AND THE CONTROL SIGNAL IS OUTPUT TO TERMINALS #10, #20, #30, #40, #50 AND #60
OF THE ENGINE CONTROL MODULE (ECU) TO OPERATE THE INJECTOR (INJECT THE FUEL). THE EFI SYSTEM PRODUCES
CONTROL OF FUEL INJECTION OPERATION BY THE ENGINE CONTROL MODULE (ECU) IN RESPONSE TO THE DRIVING
CONDITIONS.
*ESA (ELECTRONIC SPARK ADVANCE) SYSTEM
THE ESA SYSTEM MONITORS THE ENGINE CONDITION THROUGH THE SIGNALS INPUT TO THE ENGINE CONTROL MODULE (ECU)
FROM EACH SENSOR (INPUT SIGNALS FROM (1), (3), (4) TO (12) ETC.). THE BEST IGNITION TIMING IS DECIDED ACCORDING TO
THIS DATA AND THE MEMORIZED DATA IN THE ENGINE CONTROL MODULE (ECU) AND THE CONTROL SIGNAL IS OUTPUTS TO
TERMINALS IGT1, IGT2, IGT3, IGT4, IGT5 AND IGT6. THIS SIGNAL CONTROLS THE IGNITER TO PROVIDE THE BEST IGNITION
TIMING FOR THE DRIVING CONDITIONS.
*HEATED OXYGEN SENSOR (OXYGEN SENSOR) HEATER CONTROL SYSTEM
THE OXYGEN SENSOR HEATER CONTROL SYSTEM TURNS THE HEATER ON WHEN THE INTAKE AIR VOLUME IS LOW (TEMP. OF
EXHAUST EMISSIONS IS LOW), AND WARMS UP THE OXYGEN SENSOR (NO. 1 AND NO. 2) TO IMPROVE DETECTION
PERFORMANCE OF THE SENSOR.
THE ENGINE CONTROL MODULE (ECU) EVALUATES THE SIGNALS FROM EACH SENSOR (INPUT SIGNALS FROM (1), (4), (9) TO (10)
ETC.), AND OUTPUT CURRENT TO TERMINALS HTL, HTR AND HTS AND CONTROL THE HEATER.
*IAC (IDLE AIR CONTROL (ISC)) SYSTEM
THE IAC (ISC) SYSTEM (ROTARY SOLENOID TYPE) INCREASES THE RPM AND PROVIDES IDLE STABILITY FOR FAST IDLE±UP
WHEN THE ENGINE IS COLD, AND WHEN THE IDLE SPEED HAS DROPPED DUE TO ELECTRICAL LOAD AND SO ON, THE ENGINE
CONTROL MODULE (ECU) EVALUATES THE SIGNALS FROM EACH SENSOR (INPUT SIGNALS FROM (1), (4), (5), (8), (9) ETC.),
OUTPUTS CURRENT TO TERMINALS RSO AND RSC TO CONTROL IDLE AIR CONTROL VALVE.
*EGR CONTROL SYSTEM
THE EGR CONTROL SYSTEM DETECTS THE SIGNAL FROM EACH SENSOR (INPUT SIGNALS FROM (1), (4), (9), (10), ETC)., AND
OUTPUTS CURRENT TO TERMINAL EGR TO CONTROL THE EGR VALVE.
*ACIS (ACOUSTIC CONTROL INDUCTION SYSTEM)
ACIS INCLUDES A VALVE IN THE BULKHEAD SEPARATING THE SURGE TANK INTO TWO PARTS. THIS VALVE IS OPENED AND
CLOSED IN ACCORDANCE WITH THE DRIVING CONDITIONS TO CONTROL THE INTAKE MANIFOLD LENGTH IN TWO STAGES FOR
INCREASED ENGINE OUTPUT IN ALL RANGES FROM LOW TO HIGH SPEEDS.
THE ENGINE CONTROL MODULE (ECU) JUDGES THE ENGINE SPEED BY THE SIGNALS ((4), (5)) FROM EACH SENSOR AND
OUTPUTS SIGNALS TO THE TERMINAL ACIS TO CONTROL THE VSV (FOR OPENING AND CLOSING THE INTAKE CONTROL VALVE)
3. DIAGNOSIS SYSTEM
WITH THE DIAGNOSIS SYSTEM, WHEN THERE IS A MALFUNCTION IN THE ENGINE CONTROL MODULE (ECU) SIGNAL SYSTEM, THE
MALFUNCTIONING SYSTEM IS RECORDED IN THE MEMORY.
4. FAIL±SAFE SYSTEM
WHEN A MALFUNCTION HAS OCCURRED IN ANY SYSTEM, IF THERE IS A POSSIBILITY OF ENGINE TROUBLE BEING CAUSED BY
CONTINUED CONTROL BASED ON THE SIGNALS FROM THAT SYSTEM, THE FAIL±SAFE SYSTEM EITHER CONTROLS THE SYSTEM
BY USING DATA (STANDARD VALUES) RECORDED IN THE ENGINE CONTROL MODULE (ECU) MEMORY OR ELSE STOPS THE
ENGINE.

89
2. CONTROL SYSTEM
*MFI (MULTIPORT FUEL INJECTION (EFI)) SYSTEM
THE MFI (EFI) SYSTEM MONITORS THE ENGINE CONDITION THROUGH THE SIGNALS INPUT FROM EACH SENSOR (INPUT
SIGNALS FROM (1) TO (13) ETC.) TO THE ENGINE CONTROL MODULE (ECU). THE BEST FUEL INJECTION VOLUME IS DECIDED
BASED ON THIS DATA AND THE PROGRAM MEMORIZED BY THE ENGINE CONTROL MODULE (ECU), AND THE CONTROL SIGNAL
IS OUTPUT TO TERMINALS #10, #20, #30 AND #40 (CALIFORNIA), TERMINALS #10 AND #20 (EX. CALIFORNIA) OF THE ENGINE
CONTROL MODULE (ECU) TO OPERATE THE INJECTOR. (INJECT THE FUEL). THE MFI (EFI) SYSTEM PRODUCES CONTROL OF
FUEL INJECTION OPERATION BY THE ENGINE CONTROL MODULE (ECU) IN RESPONSE TO THE DRIVING CONDITIONS.
*ESA (ELECTRONIC SPARK ADVANCE) SYSTEM
THE ESA SYSTEM MONITORS THE ENGINE CONDITION THROUGH THE SIGNALS INPUT TO THE ENGINE CONTROL MODULE (ECU)
FROM EACH SENSOR (INPUT SIGNALS FROM (1), (2), (4) TO (12) ETC.) THE BEST IGNITION TIMING IS DETECTED ACCORDING TO
THIS DATA AND THE MEMORIZED DATA IN THE ENGINE CONTROL MODULE (ECU) AND THE CONTROL SIGNAL IS OUTPUT TO
TERMINAL IGT. THIS SIGNAL CONTROLS THE IGNITER TO PROVIDE THE BEST IGNITION TIMING FOR THE DRIVING CONDITIONS.
*IAC (IDLE AIR CONTROL (ISC)) SYSTEM
THE IAC (ISC) SYSTEM (ROTARY SOLENOID TYPE) INCREASES THE RPM AND PROVIDES IDLING STABILITY FOR FAST IDLE±UP
WHEN THE ENGINE IS COLD AND WHEN THE IDLE SPEED HAS DROPPED DUE TO ELECTRICAL LOAD, ETC. THE ENGINE
CONTROL MODULE (ECU) EVALUATES THE SIGNALS FROM EACH SENSOR (INPUT SIGNALS (1), (4) TO (8), (13) ETC.), OUTPUTS
CURRENT TO TERMINALS ISCO AND ISCC, AND CONTROLS THE IDLE AIR CONTROL VALVE (ISC VALVE).
*FUEL PUMP CONTROL SYSTEM
THE ENGINE CONTROL MODULE (ECU) OPERATION OUTPUTS TO TERMINAL FC AND CONTROLS THE CIRCUIT OPENING RELAY
AND THUS CONTROLS THE FUEL PUMP DRIVE SPEED IN RESPONSE TO CONDITIONS.
*A/C IDLE±UP SYSTEM
IN ORDER TO PREVENT THE ENGINE IDLING SPEED FROM DROPPING WHEN THE A/C IS OPERATING, THE A/C IDLE±UP SYSTEM
CONTROLS THE VSV (FOR A/C IDLE±UP) TO INCREASE THE ENGINE IDLING SPEED AND KEEP IT STABLE.
*EGR CONTROL SYSTEM
THE EGR CUT CONTROL SYSTEM CONTROLS THE VSV (FOR EGR) BY EVALUATING THE SIGNALS FROM EACH SENSOR INPUT TO
THE ENGINE CONTROL MODULE (ECU) (INPUT SIGNALS (1), (5), (6), (9) ETC.) AND BY SENDING OUTPUT TO TERMINAL THG OF
THE ENGINE CONTROL MODULE (ECU).
*A/C CUT CONTROL SYSTEM
WHEN THE VEHICLE SUDDENLY ACCELERATES FROM LOW ENGINE SPEED, THIS SYSTEM CUTS OFF AIR CONDITIONING
OPERATION FOR A FIXED PERIOD OF TIME IN RESPONSE TO THE VEHICLE SPEED AND THROTTLE VALVE OPENING ANGLE IN
ORDER TO MAINTAIN ACCELERATION PERFORMANCE.
THE ENGINE CONTROL MODULE (ECU) RECEIVES INPUT SIGNALS ((5), (6) ETC.), AND OUTPUTS SIGNALS TO TERMINAL ACT.
3. DIAGNOSIS SYSTEM
WITH THE DIAGNOSIS SYSTEM, WHEN THERE IS A MALFUNCTIONING IN THE ENGINE CONTROL MODULE (ECU) SIGNAL SYSTEM,
THE MALFUNCTION SYSTEM IS RECORDED IN THE MEMORY. THE MALFUNCTIONING SYSTEM CAN THEN BE FOUND BY READING
THE DISPLAY (CODE) OF THE MALFUNCTION INDICATOR LAMP (CHECK ENGINE WARNING LIGHT).
4. FAIL±SAFE SYSTEM
WHEN A MALFUNCTION OCCURS IN ANY SYSTEM, IF THERE IS A POSSIBILITY OF ENGINE TROUBLE BEING CAUSED BY
CONTINUED CONTROL BASED ON THE SIGNALS FROM THAT SYSTEM, THE FAIL±SAFE SYSTEM EITHER CONTROLS THE SYSTEM
BY USING DATA (STANDARD VALUES) RECORDED IN THE ENGINE CONTROL MODULE (ECU) MEMORY OR ELSE STOPS THE
ENGINE.

174
SRS (SUPPLEMENTAL RESTRAINT SYSTEM)
NOTICE: When inspecting or repairing the SRS (supplemental restraint system), perform the operation in
accordance with the following precautionary instructions and the procedure and precautions in the Repair
Manual for the applicable model year.

Malfunction symptoms of the supplemental restraint system are difficult to confirm, so the diagnostic trouble
codes become the most important source of information when troubleshooting.
When troubleshooting the supplemental restraint system, always inspect the diagnostic trouble codes before
disconnecting the battery.

Work must be started after 90 seconds from the time the Ignition SW is set to the ªLOCKº position and the
negative (±) terminal cable is disconnected from the battery.
(The supplemental restraint system is equipped with a back±up power source so that if work is started within
90 seconds of disconnecting the negative (±) terminal cable of the battery, the SRS may be activated.)
When the negative (±) terminal cable is disconnected from the battery, memory of the clock and audio systems
will be cancelled. So before starting work, make a record of the contents momorized by each memory system.
When work is finished, reset the clock and audio system as before and adjust the clock. This vehicle has tilt
and telescopic steering, power seat and outside rear view mirror and power shoulder belt anchorage, which
are all equipped with memory function, it is not possible to make a record of the customer, and ask the
customer to adjust the features and reset the memory.
To avoid erasing the memory of each memory system, never use a back±up power supply from outside the
vehicle.

When removing the steering wheel pad or handling a new steering wheel pad, keep the pad upper surface
facing upward. Also, lock the lock lever of the twin lock type connector at the rear of the pad and take care
not to damage the connector.
(Storing the pad with its metallic surface up may lead to a serious accident if the SRS inflates for some reason.)

Store the steering wheel pad where the ambient temperature remains below 93°C (200°F), without high
humidity and away from electrical noise.

Never use SRS parts from another vehicle. When replacing SRS parts, replace them with new parts.

Never disassemble and repair the steering wheel pad, center SRS sensor assembly or front airbag sensors.

Before repairing the body, remove the airbag sensors if during repair shocks are likely to be applied to the
sensors due to vibration of the body or direct tapping with tools or other parts.

Do not reuse a steering wheel pad or front airbag sensors.
After evaluating whether the center airbag sensor assembly is damaged or not, decide whether or not to reuse
it. (See the Repair Manual for the method for evaluating the center airbag sensor assembly.)

When troubleshooting the supplemental restraint system, use a high±impedance (Min. 10k
/V) tester.

The wire harness of the supplemental restraint system is integrated with the cowl wire harness assembly and
engine wire harness assembly.
The vehicle wiring harness exclusively for the airbag system is distinguished by corrugated yellow tubing, as
are the connectors.

Do not measure the resistance of the airbag squib.
(It is possible this will deploy the airbag and is very dangerous.)

If the wire harness used in the supplemental restraint system is damaged, replace the whole wire harness
assembly.
When the connector to the airbag front sensors can be repaired alone (when there is no damage to the wire
harness), use the repair wire specially designed for the purpose.
(Refer to the Repair Manual for the applicable Model year for details of the replacement method.)

INFORMATION LABELS (NOTICES) are attached to the periphery of the SRS components. Follow the
instructions on the notices.