ECU MITSUBISHI ECLIPSE 1990 Service Manual

ELECTRICAL - Fuses8-3q
rMULTI-PURPOSE FUSES
The multi-purpose fuses are located within the junction block at
the lower part of the instrument panel (at the driver’s seat side).
These fuses are all the blade type; 1 O-ampere, 15-ampere and
30-ampere fuses are used.
IPower supply circuitFuse No.
RatedLoad circuitapacity
(A)IBattery
t-lonition,itchBattery
IGz
ACC
IG,
10
10
10
15
15
10Automatic seatbelt control unit, buzzer, passing control relay,
key reminder switch, theft-alarm starter relay
Air conditioner control unit, air conditioner switch, heater relay,
power window relay, defogger timer, daytime running light relay
2 only>, transistor relay RadioCigarette lighter, remote controlled mirror
Door lock relay, door lock control unitAuto-cruise control unit
, AA control unit,
inhibitor switch, combination meter
ACC
IGI9
1011
12
1315
10
10
10Wiper motor, washer motor, intermittent wiper relay
Horn, headlight relay, theft-alarm control unit, daytime running
light relay
1 Auto-cruise control unit, auto-cruise control actuator,
automatic seatbelt control unit, theft-alarm control unit,
combination meter, warning light, seatbelt timer
Turn-signal and hazard flasher u.nit
14
15
16
17
10Theft-alarm horn relay
30Blower motor
15Stop light
Back up light
CM/T>, dome light relay
!Dome light. luggage compartment
Irght, foot. Irght.door-ajar warntng light, radio, MPI control unrt.AK control unit, ignition key illumination light.security lightI

8-28ELECTRICAL- Engine Electrical
IGNITION TIMING CONTROL
Reading of Input signallgnitlon power
distribution control
(selection of power
transistor actlvatlon)Control mode
I II II IControl mode
dectsion data
Basic energlzatlon
I’
Engine control unitPower
Powertranststor “A”tranststor “B”
6ELOO66The above block diagram shows the
fljnctions of the
engine control unit for ignition timing control.
One feature is that the engine control unit provides
ignition power distribution control which is neces-
sary because this engine is without a distributor, as
has been described earlier. By activating two power
transistors alternately, the primary current of two
ignition coils, one for the No. 1 and No.4 cylinders
and one for the No. 2 and No, 3 cylinders is turned onand
off. thus causing the cylinders to fire in the
order of 1, 3, 4, 2.
For ignition timing control, -optimum ignition timing.^--_
_. -.is determined by making preset corrections which
has been for engine coolant temperature, intake air
temperature an& other conditions of the ignition
advance angle that has been preset according to the
engine operating conditions. For vehicles with
tur=_.bocharger have a knocking control that corrects tl
ignition advance angle according to the presence or
absence of knocking.
The engine control unit also controls the primary
current energization time in order to secure stable
ignition energy.
These controls are explained in detail below.
--. .----- ---- --- ___. .-. ___.,.__

8-30ELECTRICAL - Engine Electrical
Ignition Advance Angle Control
While
cranking
Fixed angle(5”BTD.C)Engme coolantBarometnc‘-Intake air 1temperaturepressuretemperaturesensorsensor, sensor
Dunng normal operatlon4i+
Advance angle map valueEngine
coolantBarometricIntake airaccording to engine speed4and intake air volumetemperature- pressure__c temperature 4
correctioncorrectloncorrectton
Durtng ignition tlmmg adjustment
Fixed angle(5”BTDC)
c
=ower transistor
-$To ignition
coil
s
6EL0066The engine control unit has the ignition advance
angle value for all cylinder stroke intake air volumes
(engine load) and engine speeds stored in its
memory; this is called the basic ignition advance
angle. The control unit makes corrections in this
value according to the engine operating conditions
such as the engine coolant temperature, barometric
pressure (altitude) and intake air temperature to
obtain optimum advance angle for current engine
conditions. At the engine start and during ignition
timing adjustment, however, it is set to preset fixed
timing.
(1) WHILE CRANKING
When cranking, the ignition advance angle is fixed at
5”BTDC in synchronization with the crank angle
signal.(2) DURING NORMAL OPERATION
Basic ignition advance angle:
Map values that have been preset for all cylinder
stroke intake air volumes (engine load) and engine
speeds.Engine coolant temperature correction:
The engine coolant temperature sensor detects the
engine coolant temperature and when it is low, the
-ignition timing is advanced to improve driveability.
Barometric pressure correction:
The barometric pressure sensor detects the
barometric pressure and determines the altitude.
When the pressure is low (i.e. when the vehicle is at
a high altitude), the ignition timing is advanced to
secure maximum driveability.
intake air temperature correction:
The intake air temperature sensor detects the intake
air temperature and when it is low, the ignition
timing is delayed to prevent knocking in cold
weather. When it is high, the timing is also delayed
to prevent of knocking.
(3) DURING ADJUSTMENT OF IGNITION TIMING
When the terminal for ignition timing and idle speed
adjustment is shorted to ground, the ignition timing
is set at
5”BTDC in synchronization with the crank
angle signal, If the ignition timing does not agree
with the reference ignition timing of 5’BTDC, turn
the crank angle sensor to adjust the timing so that
the crank angle signal agrees with the reference
ignition timing. When the engine speed is approx-
imately 1,200 rpm or higher, however, the timing
advance is according to normal operation and
therefore this ignition timing adjustment is not
available.
-
. .1-_ .---

Knocking Control for Turbo Engine OnlyEngine coolant tern.Advance mapperarure correctton
value- Barometric pressurecorrectton
DelonaIlon
sensorI
lgnmon codKnockmg correcllonprimary currenr
v
Knock wbral+onKnockmg LevelDelay anglelgnmon tlmtngdetemon- delermonmon - calculallon - derermmatlon
II
Y
FatlureIdeIeclton
6FUO565Engine knocking is detected and the ignition timing
is controlled accordingly to prevent continued
knocking and to protect the engine.
When knocking is detected, the engine control unit
delays the ignition timing according to the signal
from the detonation sensor until the knocking is
eliminated (up to a maximum 12” in crank angle). In
the case of an open or short circuit of the detonationsensor harness. the timing is delayed by a fixed
angle (approximately 8” in crank angle) to prevent
knocking.Energization Time Control
While
crankinaIf knocking continues, the advance angle map value
is corrected gradually in the delay direction.
In the absence of knocking, the map value is
corrected gradually in the advance direction. In this
way, optimum ignition timing is constantly control-
led; this control is effective even when fuels of
different octane ratings are used.
This means that the engine is protected from
knocking damage even when the fuel is switched
from premium to regular or vice versa.
Synchronizedwith crank angle
sensor signalcDuring normal operation
Map value
cor-Energizatlon time
responding to- is clipped at 75% of
battery voltageignition interval
IIn order to obtain stable ignition energy, the
ener-gization time of the ignition coil primary current is
controlled as to keep current at a constant value
when the primary current is shut off.
(1) DURING NORMAL OPERATION
Basic energization time
:The increase of the ignition coil primary current
changes with the battery voltage. Therefore, the
energization time is so controlled that the primary
current at time of ignition becomes
6A. The basic
energization time is so set that it is longer when the
battery voltage is low and is shorter when the
6FUO548Energization time clip:
The new two-coil ignition system has its ignition
interval doubled when compared to the convention-
al single
coil type, allowing a longer clip time. As a
result, a long energization time is secured for
sufficient ignition energy even during high speed
operation.
(2) WHILE CRANKING
When cranking, the ignition coil is energized in
synchronization with the crank angle signal.
-

8-32ELECTRICAL - Theft-alarm System
THEFT-ALARM SYSTEM
NOOIAAAWhen the theft-alarm system has been armed by a
fixed sequence for locking the doors with the key or
without the key, if thereafter a door, the rear hatch
or the hood is opened in an unauthorized way. the
horn will sound intermittently for period of approx-
imately three minutes, and. at the same time, the
headlights will flash on and off, thus providing
audible and visual warning. signals.Furthermore, the starter circuit is interrupted in SIa way that the engine cannot be started, if
‘Lignition key is not used. Note that this system is
controlled by the electronic control unit (ECU).
This ECU includes an independent microcomputer
for the exclusive use of the theft-alarm system. This
microcomputer arms, disarms, activates and deacti-
vate the alarm system.
The system is composed of the components de-
scribed below.
Key-reminder
switchLiftgate unlock switch
!/Starter
Door key cylinder
”daytime running light relay Security
lig
ECU
I
HornOPERATION
iAbout
20 seconds after all doors are closed
and locked. the rear hatch is closed. and the
hood is closed + SYSTEM ARMED
. .‘11A door rear hatch or hood is brokenALARM ACT,“ATED
* n Engine is disabled to start.
Headlights
Iflicker
*.
.u Driver opens door with the key
I.l .
SYSTEM DISARMEDI J-0
-IDriver unlocks a door
0 Normal starting -1or rear hatch with the*D key.
- ALARM DEACTIVATED(SYSTEM DISARMED)

ELECTRICAL - Theft-alarm System8-33ARMING THE SYSTEM
After the following procedures have been completed, the SECURITY light illuminates for about 20 seconds,
and when illumination stops, the system is armed.
(1) Pull out the ignition key from the key cylinder.
(2) Open a door. (The other door is closed.)
(3) Lock the door with the key or the
keyless-locking method.
(The central door locking system will then function to lock all doors.)
NOTE(1) The system is set regardless of whether the hood and liftgate are open or
closed, and is armed as
soon as the light goes out.
(2) Even after the system has been armed, if the key is used to open the liftgate, the system will not be
activated; when the liftgate is then
closed, moreover, the system will be armed.
DISARMING THE SYSTEM
(1) The system will be disarmed if the key is used to unlock a door.
(2) If the system is armed while the driver is still in the vehicle, the system can be disarmed by inserting the
ignition key and turning it to the ACC or ON position.
(3) If the door lock is unlocked while closing the door or the door is ajar.
(4) If the door is unfastened while the SECURITY light illuminates.
ACTIVATING THE ALARM
(1) if an attempt is made to open a door, the liftgate or the hood, without using the key, while the system is
armed, the horn will sound intermittently and the headlights will flash on and off for approximately
three,
minutes.Furthermore, the starter circuit is interrupted at this time also, making starting of the engine impossible.
(2) if a further attempt at *forcible entry is made after the first three-minute alarm has finished, the
three-minute alarm will be activated again.
DEACTIVATING THE ALARM
(1) To deactivate the alarm, insert the key into the door’s key cylinder and turn the key.
(2) The alarm is deactivated and the system is disarmed when the iiftgate is unlocked with the key.
CHECKING THE SYSTEM OPERATION
The activation/operation of the system can be checked by following the steps below.
(1) Turn the ignition key to the ON position and then use the power-window switch to fully open the window
at the driver’s seat side.
(2) Turn the ignition key to the LOCK position and then remove the key from the ignition.
(3) Open only the driver’s door, and close all the other doors, as well as the hood and the rear hatch.
(4) Lock the driver’s door by the key or the
keyless-locking method.
(5) All doors will then be
locked, and the SECURITY light (within the combination meter) will illuminate; check
to be sure that illumination stops in about 20 seconds.
(6) After about two seconds have passed after the SECURITY light illumination stopped, reach through the
window of the driver’s door, pull up the lock lever to unlock the door, and then open the door.
(7) Check to be sure that, when the door is opened, the horn starts sounding and the headlights flash on and
Off.
(8) To stop the alarm, insert the key into the door’s key cylinder and turn the key.
!?iEeck the alarm for the opening of the liftgate or hood open the liftgate (or the hood) by using the
remote liftgate release lever (or the hood release lever),
located at the driver’s seat side either before the
alarm is activated by the opening of a door, or after the finish of the first three-minute alarm.

FUEL SYSTEM -Fuel Injection Control
14-41
During normal operation (including idling), the en-
gine control unit controls the injector activation time
tcThieve the stoichiometric air/fuel ratio, which
e.;res maximum efficiency of the catalytic conver-
ter, on the basis of the oxygen sensor signal.
When the air/fuel mixture is richer than the
stoichiometric ratio, there is less oxygen in the
exhaust gas and thus the oxygen sensor output
voltage is higher; hence a “mixture rich” signal is
input to the engine control unit. Then, the engine
control unit decreases the amount of fuel injected. If
the air/fuel ratio decreases to the point that and the
mixture becomes leaner than the stoichiometric
ratio, the oxygen concentration in the exhaust gas
increases and the oxygen sensor output voltage
becomes lower. Then, a “mixture lean” signal isinput to the engine control unit.
Upon input of this signal, the engine control unit
increases the feedback correction factor, thus caus-
ing more fuel to be injected.
By means of the above-mentioned controls (collec-
tively called “feedback control”), the air-fuel mixture
is maintained at the stoichiometric ratio.
Under the following specific conditions, this feed-
back control is not performed, in order to improve
driveability.
(11
(2)
::I
(5)While cranking the engine
During engine warm-up when engine coolant
temperature is less than
45°C (113°F)During acceleration/deceleration
During high load operation
When oxygen sensor is not functioning
IOPEN LOOP CONTROL
Engine speed rpm6FUO274
II
80(176)
Coolant temperature “C (“Fj6FlJO276
I425(77)
Intake air temperature “C (“F)1~40,0IThe amount of fuel injected is controlled according to the map
value* preset for each engine speed and A/N (refer to
P.l4-39FOR YOUR INFORMATION).
*Map value: Value preset and stored in the ROM of the engine
control unit.
ENRICHMENTWhen the throttle valve is wide open, control is performed to
increase the amount of fuel injected, in order to secure good
driveability under high load conditions.
FUEL INJECTION CONTROL DURING ENGINE WARM-UP
To secure good driveability when the engine is still cold, control
is performed to increase the amount of fuel injected when the
engine
cooiant temperature is low.
FUEL INJECTION CONTROL ACCORDING TO INTAKE AIR
TEMPERATUREGiven a constant intake air volume, the change in intake air
temperature alters the intake air density, resulting in an
improper air-fuel ratio.
To correct this deviation, the amount of fuel injected is
controlled; i.e., the amount of fuel injected is increased to
compensate for the higher
intake air density caused by the
decreased intake air temperature.

14-42
FUEL SYSTEM- Fuel Injection Control
4
Fz.or.c
4:0/
E
{!*760 (301Barometric pressure
mmHg (in.Hg) 6Fuo9z
c
Timet
6FUO279Drivecurrent
0: bri
F2JJ’ ipe; II
I+-JValve opening timi16240:
E‘C
F
.-
is
3
3:\Battery voltage
V162406
80 (176)Coolant temperature
“C (“F)162401HIGH ALTITUDE COMPENSATION
A change in barometric pressure, which may be caused by
change in altitude, alters the intake air density, resulting in an
improper air-fuel ratio. To compensate this deviation, the
amount of fuel injected is controlled; i.e., the amount of fuel
injected is decreased to compensate for the lower intake air
density caused by the decreased barometric pressure, or the
higher altitude.
CONTROL FOR FUEL ENRICHMENT DURING ACCELERA-
TIONDuring acceleration at low and middle loads, fuel supply rate is
increased to improve acceleration performance.
FUEL DECREASE CONTROL DURING DECELERATION
During deceleration, fuel supply rate is decreased to improve
fuel economy.
BATTERY VOLTAGE COMPENSATION
As described earlier in “INJECTOR”, the needle valve of the
injector is pulled to the fully open position when current flow-
through the solenoid coil. This means that there is a time I;
between the time when the current starts flowing and when
the needle valve starts opening. This time lag is called the dead
time.
The dead time varies with different battery conditions:: the
lower the battery voltage, the longer the dead time.
Since the injector activation duration depends on the intake air
volume and other factors, a longer dead time means a shorter
activation duration, or a smaller amount of fuel injected. This
results in an improper air-fuel ratio. At such times, the solenoid
coil is energized for a longer period of time depending on the
current battery voltage to correct the valve opening time, thus
ensuring that the optimum amount of fuel is injected.
Fuel Injection Control at Starting
When the engine is cranked, the map value preset according to
the engine coolant temperature is used as the basic injector
activation duration, to which the high altitude compensation is
applied..

14-72
._FUEL SYSTEM
- Auto-cruise Control System
___ -ACTUATOR OPERATION
IF SET TO A FIXED SPEED
When the SET switch is set to the ON position, the
control unit causes current to flow to the actuator’s
electromagnetic clutch coil; the clutch plate is then
attracted, the ring gear of the planetary gear is
secured, and, at the same time, the path from the
ECU to the DC motor becomes conductive and the
DC motor begins to rotate at high speed.As shown in the illustration, the rotation of the DC
motor is transmitted to the worm gear
--, worm
wheel, sun gear (unified)
+ planetary pinion.
Because the ring gear is fixed at this time, the
planetary pinion revolves while rotating around the
sun gear, and, because the planetary pinions are
installed to the carrier, the carrier and the unifiedselectcr drive shaft and selector rotate.
Clutch plate
<
7 Limit switch
DC motorSelector
Magnetic clutch coil Magnetic clutch coil
Selector diive shaft
MAIN switchTrl
4sTn
aAuto-cruise control
unit07AOO11The selection of the direction (PULL or RELEASE) of the
selector rotation is performed by the reversal of the direction of
conductivity to the motor, and this is controlled by the ECU.
Current Flow in PULL Rotation
.(soiid-line arrows)
The control unit microcomputer output causes transistors
Tr,and Tr, to be turned ON. Then, current flows from transistor
Tr,to DC motor,‘transistor
Tr,, and ground. As a result, the DC
motor rotates in the PULL direction.
Current Flow in RELEASE Rotation (dotted-line arrows)
Microcomputer output causes transistors
Tr2 and Tr3 to be
turned ON. Then, current flows from transistor
Tr3 to DC
motor, transistor
Tr2, and ground, resulting in the DC motor
rotating in the RELEASE direction.
The electromagnetic clutch is controlled by the MAIN and
CANCEL switches. When the MAIN switch is in the
01\L.position, it keeps the clutch plate attracted under norm
conditions (i.e. where there is no cancel condition).

- -----.--..
14-76FUEL SYSTEM -Auto-cruise Control System
Ignition switch
IGI
9
RESUActuator electro-
Microcomputer
1 T 1
rn’Auto-cruise control unit
Autocruisecontrol switch
IGlMAIN
;FF -+++&Control unit
power supply
terminal voltage
03AO264NC: Normally closed
07*0040
AUTO-CRUISE CONTROL SWITCH
The auto-cruise control switch is built into the steering column
switch.MAIN SWITCH
The MAIN switch is an automatic reset type switch to turn ON
and OFF the power supply of the control unit.
COMMAND INPUT SWITCHES (SET and RESUME)
The SET and RESUME switches function to input the control
signals of the auto-cruise control system; both are the
automatic-reset type.
These switches are ON while pressed and OFF when released.
For the ECU’s input interface, each of the input terminals is
pulled up by the battery voltage; the terminal voltage is LOW
level
(OV) when the switch is ON, and is HIGH level (about 12V)when the switch is OFF. These voltage changes (digital
sig*)are input to the microcomputer as ON and OFF signals
o.:
switches.
.