Toyota 1993 MR2, Схемы проводки, Страница: 129 / 189

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EHPS (ELECTRO HYDRAULIC POWER STEERING)
THE EHPS (ELECTRO HYDRAULIC POWER STEERING) SYSTEM FUNCTIONS TO CHANGE THE FORCE REQUIRED FOR STEERING
MANEUVERS, AND THEREBY PROVIDE THE IDEAL STEERING FEELING FOR AT VEHICLE SPEEDS AND STEERING CONDITIONS.
THIS IS DONE BY THE POWER STEERING ECU CONTROLLING THE HYDRAULIC PRESSURE ACTING UPON THE HYDRAULIC
REACTION CHAMBER (LOCATED IN THE GEAR BOX CONTROL UNIT) BY REGULATING THE POWER STEERING MOTOR’S SPEED
(AND HENCE THE AMOUNT OF FLUID FLOW).
EHPS OPERATION
WHEN THE IGNITION SWITCHED ON, STARTING CURRENT FLOWS FROM THE GAUGE FUSE TO TERMINAL IGB OF THE POWER
STEERING ELECTRONIC CONTROL UNIT, TERMINAL VS OF THE STEERING POSITION SENSOR, AND TERMINAL (A) 4 OF THE
POWER STEERING DRIVER.
THE VEHICLE SPEED IS DETECTED AT THE SPEED SENSOR, AND SIGNALS ARE INPUT AS CONTROL SIGNALS TO TERMINAL SPD
OF THE POWER STEERING ELECTRONIC CONTROL UNIT AND TO TERMINALS SS1 AND SS2 OF THE POWER STEERING
ELECTRONIC CONTROL UNIT.
WHEN THE ENGINE IS STARTED, SIGNALS ARE INPUT TO TERMINAL EFI OF THE POWER STEERING ELECTRONIC CONTROL UNIT
FROM THE ENGINE OF TERMINAL PSCT OF THE ENGINE AND ECT ECU. AS A RESULT, THE CURRENT APPLIED TO TERMINAL IGB
OF THE POWER STEERING ECU FROM THE GAUGE FUSE FLOWS FROM TERMINAL MRLY OF THE POWER STEERING ECU
→
TERMINAL (B) 1 OF THE POWER STEERING RELAY
→
TERMINAL (B) 2
→
GROUND, AND THE POWER STEERING RELAY IS
SWITCHED ON. AS A RESULT, THE CURRENT APPLIED TO TERMINAL (A) 1 OF THE POWER STEERING RELAY FROM THE ABS FUSE
FLOWS FROM TERMINAL (A) 2 OF THE POWER STEERING RELAY
→
TERMINAL (B) 1 OF THE POWER STEERING DRIVER AND TO
TERMINAL (A) 1 OF THE POWER STEERING MOTOR.
IF THE VEHICLE SPEED IS LOW, THE SPEED OF THE POWER STEERING MOTOR IS INCREASED BY INCREASING THE VOLTAGE OF
THE CURRENT THAT FLOWS FROM TERMINAL (A) 1 OF THE POWER STEERING MOTOR TO TERMINAL (A) 2 OF THE POWER
STEERING MOTOR
→
TERMINAL (B) 2 OF THE POWER STEERING DRIVER
→
TERMINAL (C) 2
→
GROUND, WITH THE RESULT THAT
THE VOLUME OF FLOW OF THE POWER STEERING FLUID BECOMES GREATER, THUS PROVIDING A LIGHT STEERING FEELING.
WHEN THE VEHICLE SPEED IS HIGH, THE SPEED OF THE POWER STEERING MOTOR DECREASES AS A RESULT OF THE REDUCED
VOLTAGE APPLIED TO THE POWER STEERING MOTOR, AND THUS THE VOLUME OF FLOW OF THE POWER STEERING FLUID IS
REDUCED, SO THE STEERING FEELING IS MORE RESISTANT.
P 2
POWER STEERING ECU
1–GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON
12–GROUND : ALWAYS CONTINUITY
5–GROUND : 1 PULSE EACH 40 CM (DRIVER VEHICLE SLOWLY)
C14
STEERING POSITION SENSOR [COMB. SW]
14–GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON
12–GROUND : ALWAYS CONTINUITY
P 1
POWER STEERING DRIVER
(A)4–GROUND : APPROX. 12 VOLTS WITH IGNITION SW ON
(B)2–GROUND : ALWAYS CONTINUITY
: PARTS LOCATION
CODE SEE PAGE CODE SEE PAGE CODE SEE PAGE
C 1 24 (5S–FE), 25 (3S–GTE) E 6 C 24 (5S–FE) P 7 27
C11 A 26 E 8 D 24 P 8 A 27
C12 B 26 J 3 26 P 9 B 27
C14 26 P 4 C 27 P10 B 27
E 6 A 25 (3S–GTE) P 5 B 27 P11 A 27
E 6 B 24 (5S–FE) P 6 A 27
: RELAY BLOCKS
CODE SEE PAGE RELAY BLOCKS (RELAY BLOCK LOCATION)
1 20 R/B NO. 1 (LEFT KICK PANEL)
5 21 R/B NO. 5 (FRONT LUGGAGE COMPARTMENT RIGHT)
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODE SEE PAGE JUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
3A
3C 21 COWL WIRE AND J/B NO. 3 (BEHIND COMBINATION METER)
3D
( )
SYSTEM OUTLINE
SERVICE HINTS