1992 MAZDA PROTEGE ECU

F FUEL
23UOFX-12:
0-6V
23UOFX- 131
to the terminal 2U or 2V (MTX), 3U or 3V (ATX)
hat the green and red lamps flash alternately.
nd No,3.....ECU terminal 2U (MTX)
3U (ATX)
. . . ..ECU terminal 2V (MTX)
3V (ATX)
6. Increase the engine speed to 4,000 rpm and then suddenly
release the throttle.
7. Verify that the red indicator lamp illuminates while the en-
gine speed is above approx.
1,900 rpm on deceleration.
t aced maximum rpm over 3 sec.
8. Increase the engine speed and verify that the maximum rpm
does not exceed specification.
.
.
. ..“.*..1”*“.-.“.....*......*...
Approx. 7,300 rpm
. . ..I......m....“.....*........m Approx. 6,300 rpm
F-l 44

DECHOKE CONTROL SYSTEM t-
DECHOKE CONTROL SYSTEM
DESCRIPTION
To facilitate starting the engine when the spark plugs become fouled, such as when the engine is flooded,
fuel injection is cut if the throttle valve is held wide open while cranking and the engine coolant temperature
is O°C (32OF) or below. This allows the spark oluas to drv and purges excess fuel from the cylinders.
f-- ECU _
. IGNITION SWITCH (START)
l ENGINE SPEED BELOW 500 rpm ’
l THROTTLE VALVE FULLY OPEN
l ENGINE COOLANT TEMPERATURE ;
BELOW
0% (32°F) I FUEL CUT
OBUOFX-19
I / / ‘ I
SYSTEM OPERATION
1.
2. Check if the engine coolant temperature is below O°C
(32OF).
If the engine coolant temperature is above O°C (32OF), dis-
connect the water thermosensor connector and connect an
approx. 10 kB resistor to the connector.
03UOFX.198 3. Turn the ignition switch to START and verify that the injec-
OBUOFX-19! 3
tor operating sound is heard.
4. Depress the accelerator pedal fully and turn the ignition
switch START. Verify that no injector operating sound is
heard.
F-l 45

CONTROL SYSTEM F
CONTROLSYSTEM
PREPARATION
SST
49 9200 162
Engine Signal
Monitor
49 HO18 9Al
Self-Diagnosis
Checker
49 GO1 8 904
Sheet For
inspection of
ECU
For
inspection of
oxygen sensor
For
inspection of
ECU 49 GO18 903
Adapter
harness
49 BO19 9AO
System
Selector For
inspection of
ECU
For
inspection of
oxygen sensor
03UOFX-20
F-l 47

F CONTROL SYSTEM
STRUCTURAL VIEW
23UOFX-1:
1. Engine control unit (ECU) 8. Solenoid valve (Pressure regulator control)
- .--
Removal / Installation . . . . . . . . . . . . . . . . page F-149
Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page F-149
2. Circuit opening relay
Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . page F-l 29
Inspection ,...,........................... page F-l 29
3. Clutch switch (MTX)
inspection . . . . . . . . . . . . . . . . . . . . . . . . . page F-l 72
4. Airflow meter (With intake air thermosensor)
Inspection .,..........,...,............... page F-l 68
5. ISC valve
Inspection .,*,........,.,.........,....... page F-116
Removal / Installation . . . . . . . . ,.... page F-l 09
G-Throttle sensor
Inspection . . . . . . . . . . . . , . . . . . . page F- 169
Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . page F-l 09
7. Solenoid valve (VICS) [DOHC]
Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page F-l 18 Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9. Water thermosensor
Inspection. . . . . . . .
Removal I Installation ....I..........
10. Solenoid valve(Purge control)
Inspection ,............ ,..................
11, Main relay (FUEL INJ relay)
Inspection. ..,............................
12. Neutral switch (MTX)
Inspection ,.,,,,....I.l,,.........I.......
Replacement . . . . . . .
13. Oxygen sensor
Inspection,. . . .
Replacement . , . . . .
14. P/S pressure switch
Inspection . . ..__.._._._........
Replacement . , . . . . . . . . . . . . . page t-135
page F-l 68
page F--l 68
page F-l 40
page F-172
page F-l 73
page F-173
page F-171
page F-172
--
page F-173
page F-173
F-l 48

CONTROL SYSTEM F
SMALL TYPE
03UOFX.20:
03UOFX-20
23UOFX-13
TERMINALS
AANDB
c “.w a ,.1/M rrmrrm
_-
03UOFX-201
ENGINE CONTROL UNIT (ECU)
Removal / Installation
1. Remove the side walls (driver’s side and passenger’s side).
(Refer to page S-94.)
2. Remove the bolts and nuts.
3. Disconnect the ECU connectors.
4. Install a
new ECU in the reverse order of removal.
Inspection
1. Disconnect the ECU connectors.
2. Connect the
SSTs (Engine Signal Monitor and Adapt-
er)
to the ECU as shown,
3. Set the SST (Sheet) on the Engine Signal Monitor with
the specified side fancing up as shown.
Note
l MTX...48 PIN
l ATX...84 PIN
4. Measure the voltage at each terminal.
(Refer to pages F-150 to F-167.)
5. If any ECU terminal voltage is incorrect, check the related
input or output devices and wiring. If no problem is found,
replace the ECU. (Refer to above.)
Caution
l Never apply voltage to SST terminals A and B.
F-l 49

CONTROL SYSTEM F
VB: Battery voltage
incorrect voltage POBSible cause
Alwvs OV’ l ROOM IOA fuse burned l Open circuit in wiring from ROOM IOA fuse to ECU terminal 1A
Always OV
l Main relay malfunction (Refer to page F-171) l Open or short circuit in wiring from main relay to ECU terminal 1B
I
Always OV (Starter turns) l Open or short circuit in wiring from starter interlock switch (USA), ignition
switch (CANADA), to ECU terminal 1C
I
Always OV
Always Vs
Always approx. 5V
l Main relay (FUEL IWJ relay) malfunction (Refer to page F-171) l Open circuit in wiring from main relay to diagnosis connector terminal +B l Open or short circuit in wiring from diagnosis connector terminal MEN to
ECU terminal 1D
l Poor connection at ECU connector l ECU malfunction
l ECU malfunction
Always below
23 MIL always ON
MIL never ON
l Short circuit in wiring from combination meter to ECU terminal 1E l ECU malfunction
l Open circuit in wiring from combination meter to ECU terminal 1E
I
Always Ve l Poor connection at ECU connector l ECU malfunction
Always below
2.5V
Always
VB
No display on Self- * Main relay (FUEL INJ relay) malfunction (Refer to page F-171)
Diagnosis Checker l Open circuit in wiring from main relay to diagnosis connector terminal +B
“88” displayed and
l Open or short circuit in wiring from diagnosis connector terminal FEN to
buzzer sounds con- ECU terminal 1F
tinuously
l Poor connectron at ECU connector l ECU malfunction
Always OV
l Short circuit in wiring from igniter to ECU terminal 1G
I -
I -
I
I -
I -
I
Always below
2.5V
Always VB AIC does not operate l A/C relay malfunction (Refer to page U-55) l Open circurt in wiring from ignition switch to A/C relay l Open circuit in wiring from A/C relay to ECU terminal 1J
A/C switch OFF but
l Short circuit in wiring from A/C relay to ECU terminal IJ
AIC operates l ECU malfunction
l Poor connection at ECU connector l ECU malfunction
Always below l.OV
l Short circuit in wiring from diagnosis connector terminal TEN to ECU termi-
nal 1K
Always Vs
l Open circuit in wiring from diagnosis connector terminal TEN to ECU termi-
nal 1K
l Open circuit in wiring from diaonosis connector terminal GND to ground
Always below
2.W
Always Va DRL ON when ignition
l Short circuit in wiring from DRL relay to ECU terminal IL
switch ON l Short circuit in wiring from DRL relay to DRL unit
DRL never ON
l Open circuit in wiring from DRL relay to ignition switch
l Parking brake switch always ON l DRL unit malfunction (Refer to page T-33)
23UOFX- 134
F-l 51

CONTROL SYSTEM F
Ve: Battery voltage
Incorrect voltage
1, -
Always below l.OV
Always Ve
Always below I.OV (Stoplight OK)
Always below l.OV
Always
VB
Always below 25V (Blower fan OK)
Always
VB (Blower fan OK)
Always below 1 .OV
(Electrical cooling fan OK)
Always below 1 .OV (Blower fan OK)
Always
VB (Blower fan OK)
Always below
1 .ov
Always below l.OV Illumination lamp
ON when rear
window defroster
switch ON
Illumination lamp
never ON
(Headlights OK)
Always below l.OV
Always Ve Possible cause
-
l Throttle sensor misadjustment (Refer to page F-169)
l Short circuit in wiring from throttle sensor to ECU terminal 1N l ECU malfunction
l Throttle sensor misadjustment (Refer to page F-169) l Open circuit in wiring from throttle sensor to ECU terminal IN l Open circuit in wiring from throttle sensor to ECU terminal 2D
l Open circuit in wiring from stoplight switch to ECU terminal 10
l P/S pressure switch malfunction (Refer to page F-173) l Short circuit in wiring from P/S pressure switch to ECU terminal 1P l ECU malfunction
l P/S pressure switch malfunction (Refer to page F-173) l Open circuit in wiring from P/S pressure switch to ECU terminal 1P l Open circuit in wiring from P/S pressure switch to ground
l A/C switch malfunction (Refer to page U-55) l Short circuit in wiring from A/C switch to ECU terminal 10 l Poor connection at ECU connector l ECU malfunction
l A/C switch malfunction (Refer to page U-55) l Open circuit in wiring from A/C switch to ECU terminal 1Q l Open circuit in wirina from A/C switch to blower control switch
l Open or short circuit in wiring from fan relay to ECU terminal 1R l ECU malfunction
l Short circuit in wiring from blower control switch to ECU terminal 1s l Poor connection at ECU connector l ECU malfunction
l Open circuit in wiring from blower control switch to ECU terminal IS
I
l Open or short circuit in wiring from rear window defroster switch to ECU
terminal 1 T
l Open circuit in wiring from ignition switch to rear window defroster switch l Rear window defroster switch malfunction (Refer to page T-21)
l Open or short circuit in wiring from headlight relay to ECU terminal 1U
(Refer to page F-152)
l Neutral switch malfunction (Refer to page F-173) l Clutch switch malfunction (Refer to page F-172) l Short circuit in wirino from ECU terminal IV to neutral or clutch switch
l Neutral switch malfunction (Refer to page F-173) l Clutch switch malfunction (Refer to page F-172) l Open circuit in wiring from ECU terminal 1V to neutral or clutch switch l Poor connection at ECU connector
23UOFX-136
F-l 53

CONTROL SYSTEM
Ve: Battery voltage
Incorrect voltage
I Possible cause
4bove OV
l Poor contact at ground terminal l Open circuit in wiring from ECU to ground
Always approx. OV or approx. 2V
l Refer to Code No.02 Troubleshooting (Refer to page F-86) -
r\lways approx. OV or approx. 1.W - l Refer to Code No.03 Troubleshooting (Refer to page F-88)
Approx. 4.5-5.5V (California)
Always OV (Canada)
l Open circuit in wiring from ECU terminal 2H to ground
l Short circuit in wiring from ECU terminal 2l-i to main relay (FUEL INJ relay) - -
Approx. 4.5--55V l ECU malfunction
Always OV
l Short circuit in wiring from ECU terminal 2K to throttle sensor, or airflow
meter
Below 4.5V or above 5.5V
l Poor connection at ECU connector l ECU malfunction
1
l ECU malfunction
Always OV
l Throttle sensor malfunction (Refer to page F-169) l Short circuit in wiring from ECU terminal 2L to throttle sensor l Poor connectron at ECU connector l ECU malfunction
Always 4.5--5.W
Always constant
l Throttle sensor misadjustment (Refer to page F-169) l Open circuit in wiring from ECU terminal 2L to throttle sensor l Open circuit in wiring from ECU terminal 2L to ECU terminal 2D
l Open circuit in wiring from ECU terminal 2M to throttle sensor
l Open circuit in wiring from ECU terminal 2K to throttle sensor l Open circuit in wiring from ECU terminal 20 to throttle sensor
Always above 1V 1
l Throttle sensor misadjustment
OV after warm-up
Always approx. 1V after warm-up (
l Refer to Code No.15 Troubleshooting (Refer to page F-98)
I * Refer to Code No.1 7 Troubleshooting (Refer to page F-100)
Always OV or 4.5-5.5V
Always OV or 4.5~-5.W
I l
Refer to Code No.08 Troubleshooting (Refer to page F-90) l
Refer to Code No.10 Troubleshootrng (Refer to page F-94)
Always OV or 4.5-5.W l
Refer to Code No.09 Troubleshooting (Refer to page F-92) -
23UOFX-131
F-l 55