1987 MAZDA 626 fuel

CONTROL SYSTEM 4C
Output Devices and In put Devices (Leaded fuel)
IGNITION SWITCH
(ON POSITION) X X X X X O X X X X O
TEST CONNECTOR X X X O X X X X X O X
KNOCK SENSOR X X X X X X X X X o X
ELECTRICAL LOAD
CONTROL UNIT X X X O X X X X X X X
P/S PRESSURE SWITCH X X X o X X X X X X X
A/C SWITCH X X X o X X X X O X X
IGNITION SWITCH (STA POSITION) O O X o O X O X X O X
NEUTRAL AND
CLUTCH SWITCH O X X o X X X X X X X
INTAKE AIR THERMO SENSOR X X X X X X O X X X X
WATER THERMO SENSOR O X X o X X O X X O o
IDLE SWITCH o X X o X X o X X O X
VARIABLE RESISTOR (IN AIR FLOW SENSOR) o X X X X X X X X X X
AIR FLOW SENSOR o X X X X X X X X O O
Ne SIGNAL o o X O o X O o X o O
G SIGNAL X O X X X X X X X X X

INPUT

DEVICE

OUTPUT

DEVICE

FUEL

INJECTION

AMOUNT
FUEL

INJECTION

TIMING
AIR
VALVE
ISC

VALVE

FUEL

PUMP

CONTROL
MAIN

POWER

CONTROL

SOLENOID

VALVE

(PRESSURE

REGULATOR

CONTROL)

SOLENOID

VALVE

(VARIABLE

INERTIA

CONTROL)

A/C
RELAY

IGNITER
AIR

FLOW

SENSOR

(BURN-OFF)

INPUT

DEVICE

OUTPUT

DEVICE

INJECTOR
BAC

VALVE

CONTROL
RELAY
SOLENOID

VALVE

(PRESSURE

REGULATOR

CONTROL)

SOLENOID

VALVE

(VARIABLE

INERTIA

CONTROL)

A/C
RELAY

IGNITER
AIR

FLOW

SENSOR

(BURN-OFF)

76G04C-168
4C—93

4C CONTROL SYSTEM
Output Devices
and
Engine Conditions (Unleaded fuel)

REMARK

*
Above

7,000

rpm:

fuel

cut

'Coolant

temp.:
below

50°C

(122°F)

41 Coolant
temp:

below

70°C

(158°F)

*2 Engine
speed
above
1,700
rpm
*3 Engine

speed:

1,500—3,500

rpm

*
During
hot

start

only

*
Engine
speed:
above

5,200

rpm

'Engine

speed:
above

3,000

rpm

'Delays

0.5
second

IGN:

ON

(ENGINE
NOT RUNNING)

No

injection

No bypass OFF
(main

fuel

pump

not
operated)
OFF
OFF
z
1

IDLE

(THROTTLE
VALVE
FULLY CLOSED)
Rich

and

i
lean
Sequential
(once

per

two

revolutions)
OFF

o en C3 UJ
z
"After

start-
ing:

ON

(Vacuum

cut) OFF
o

DECELE-
RATION
'Fuel

cut

L

Small
amount
of
bypass
air
N (1st
stage
operate:

o
o Ho 3 O CO CD > CO >
>; CO
CO c o
c o o

HEAVY
LOAD
•ST c
Closed

Small
amount
of
bypass
air

-co-CD CO
N (1st
stage
operate:

In CD 2? 03 a. o CD o> CO to "O c

*3 OFF (EGR)

o Ho 3 O CO CD > CO >
03 k-o CO c 03 CO z o *
CD c O) c 03 c o
c o o a 3

ACCELE-
RATION
Rich

o •*—• 3 o > CD
O

Small
amount
of
bypass
air

03 Q. O Q. E 3

ON

O
In CD 2? 03 a. o CD o> CO to "O c
ON
(EGR cut)
:F (Vacuum
to
pressure

regulatt

03 3 -C CO o
c 03 CS3 > X o o
z o * CO •o c CD Q. CD T3
C CO CD o "O 3= O c: 3 CO
LL LL o

MEDIUM
LOAD
WARM
Rich

and lean

|
Q. CD O
CD D
C CO E
CVJ.
z o fS *
*3 OFF (EGR)
:F (Vacuum
to
pressure

regulatt

E 3 3
c 03 i t 3 G, LL LL
T3 CD O c CO > "O <
C CO CD o "O 3= O c: 3 CO
LL LL o

MEDIUM
LOAD

COLD

ro
c CD 3 cr
z O "a CD a? CD CL o

F (2nd
stage
not
operated)
:F (Vacuum
to
pressure

regulatt

z o * O «

WARMING
UP

(DURING
IDLE)
Rich

CD CO c CD Q-O
o
c 3 CO O CO E CO
o c F (2nd
stage
not
operated)

tr O UJ
z o
O
LL z
Fixed

at

BTDC

12°

CRANKING
(COLD
ENGINE)
1
group
(twice

per

revolution)

CO
«
CD urn i CO
CO
LL LL O
LL O * « o o
LL LL o
Fixed
at

BTDC

6°

z o

SOLENOID
VALVE
(PRESSURE
REGU-

LATOR

CONTROL)

CC
o z o o iii z
o z 111

OUTPUT
DEVICE
FUEL

INJECTION

AMOUNT FUEL
INJECTION
TIMING
AIR

VALVE

'
ISC

VALVE
FUEL
PUMP

CONTROL
MAIN
POWER
CONTROL
SOLENOID
VALVE
(No.1
PURGE)
SOLENOID

VALVE

(NO.2

PURGE)
SOLENOID
VALVE
(EGR)
SOLENOID
VALVE
(PRESSURE
REGU-

LATOR

CONTROL)
SOLENOID
VALVE
(VARIABLE
INE
TIA
CONTROL)

> <
Ul oc oc o
£T u. O 1 z oc 3 m
oc o

OUTPUT
DEVICE
INJECTOR
BAC
VALVE
CONTROL
RELAY
SOLENOID
VALVE
(No.1
PURGE)
SOLENOID

VALVE

(NO.2

PURGE)
SOLENOID
VALVE
(EGR)
SOLENOID
VALVE
(PRESSURE
REGU-

LATOR

CONTROL)
SOLENOID
VALVE
(VARIABLE
INE
TIA
CONTROL)

tn z Ul (0 z Ul o >-X o
A/C

RELAY

IGNITER

z Ul (O
=5 o
IL oc <
76G04C-169
4C—94

CONTROL SYSTEM
4C

Output Devices
and
Engine Conditions (Leaded fuel)

REMARK

E Q
O O O r-»" CD > o n <

fuel
cut

'Coolant

temp.:

below

50°

(122°F)

*
During

hot
starting
only

*
Engine

speed:

above

5,400

rpm

'Delays

0.5

seconds

IGN:
ON
(ENGINE
I
NOT
RUNNING)

o
z
injection
No
bypass
OFF

(main

fuel

pump

not
operated)
OFF
LL
I

IDLE
(THROTTLE
VALVE
FULLY
CLOSED)
Rich

I
Sequential (once
per
two

revolutions)
"After

start-
ing:
ON

(vacuum

cut)
O

DECELE-
RATION

i

i
'Fuel

cut

•o CD CO "co" CD ts o to 3 o CO CD > CO
CO c o
c o o

HEAVY
LOAD
sz "co" c
O o CO CO CO Q. >. -O
O
CD Q. O CL E CL ® D
C CO F
o 08 3 u> £ CD 3 CO 0) CD
o to 3 o CO CD > CO
z

c o o c
B

ACCELE-RATION

ir o 3 0 > CD 1 O
C
O E CO
"CO
CD Q. O CL E CL ® D
C CO F
z

o 08 3 u> £ CD 3 CO 0) CD
CD e 3 SZ CO o
O * CO
c CD CL CD T3
c CO 8 "D

'
MEDIUM
LOAD
WARM
Normal

CD Q. CD O
E CO
z
O
o o_ O
E
3 3
o CO ^ LL LL O
E 3 3 O CO
•o "O <
c
3
m
LL LL o

'
MEDIUM
LOAD
COLD

.H C CD 3 CT
o_ O
E
3 3
o CO ^ LL LL O

z
o *

WARMING
UP

(DURING
IDLE)
Rich

CD CO

*Open

B
3
CO
O
CO
E
<®
LL
Fixed

at
BTDC
12°

CRANKING
(COLD
ENGINE)
1
group
(twice

per

revolution)

CO
«
0)
>,
u>n w-CO
o

OFF
Fixed

at

BTDC

6°
ENGINE
CONDITION
OUTPUT
DEVICE
FUEL
INJECTION

AMOUNT
'
FUEL
INJECTION

TIMING
AIR

VALVE
ISC
VALVE
FUEL
PUMP
CONTROL MAIN
POWER
CONTROL
SOLENOID
VALVE
(PRESSURE
REGU-

LATOR

CONTROL)
SOLENOID
VALVE
(VARIABLE
INER-
TIA
CONTROL)

(T ik 0 1 z DC 3
ffl

OC o tn

OUTPUT
DEVICE
INJECTOR
BAC
VALVE
CONTROL
RELAY
SOLENOID
VALVE
(PRESSURE
REGU-

LATOR

CONTROL)
SOLENOID
VALVE
(VARIABLE
INER-
TIA
CONTROL)

A/C

RELAY

IGNITER

Z Ul tn
£ o
ik DC <
76G04C-170
4C—95

4C CONTROL SYSTEM
EGI MAIN FUSE
Inspection
Check the continuity of EGI main fuse.
69G04A-161
CONTROL RELAY
Power Supply Circuit
1. Check that a "clicking" sound is heard at the con-
trol relay when turning the ignition switch ON and
OFF.
Note
The control relay is located under the center
console.
76G04C-171
2. Apply 12V to the 2B terminal and ground the 2D
terminal of the control relay.
3. Check voltage at the terminals with an voltmeter.
terminal
Terminals Grounded Not grounded
2C 12V OV
2E 12V OV
76G04C-172
From EGI From '9' From Ig. main fuse switch (ON) / switch
(ST)
To C/U / 9round To main To injector fuel Pump
Fuel Pump Circuit
1. Apply 12V and a ground to the terminals described
below and check the terminals with an ohmmeter
or voltmeter.
Terminal applied 12V
Terminal
grounded
Terminal checked
Correct condition
1B 1D 2F-1A Continuity
2F 1C 1A ADDrox.12V
76G04C-173
4C-96

CONTROL SYSTEM 4C
Terminal Voltage
If the input and output devices wiring are normal, but the engine control unit terminal voltage is incor-
rect, replace the engine control unit.
Terminal Input Output Connection to Voltage (After warming-up) Remark Terminal Input Output Connection to Ign: ON Idle Remark
1A — — — — — —
1B o Self-Diagnosis Checker (Code No.)
For 3sec. after ignition switch OFF ->• ON: below 2.5V (Buzzer sounds) After 3sec.: approx. 12V (Buzzer does not sound)
• Using Self-Diagnosis Check-er and test con-nector grounded • Buzzer sounds: below 2.5V • Buzzer does not sound: approx. 12V
1C o
Solenoid valve (Variable inertia control) Approx. 12V
Above 5200 rpm (Unleaded fuel) or 5400 rpm (Leaded fuel): Below 2.5V
1D o Self-Diagnosis Checker (Monitor lamp)
For 3sec.after igni-tion switch OFF -» ON:
approx. 5V (light il-luminates)
After 3sec.: approx. 12V (light does not illuminate)
(Test connector grounded) approx. 5V (Test connector not grounded) Monitor lamp ON: approx. 5V Monitor lamp OFF: approx. 12V
With Self-Diagnosis
Checker
1E O Idle switch Accelerator pedal released: OV
Accelerator pedal depressed: approx. 12V
1F o A/C relay A/C switch ON: below 2.5V
A/C switch OFF: approx. 12V Blower motor ON
1G O Neutral or clutch switch
In-gear condition Clutch pedal depressed: approx. 12V Clutch pedal released: OV
MTX (Neutral: con-stant approx. 12V)
1H
(U/F) o Water thermo
switch
Approx. 12V Radiator temp.: be-low 17°C (63°R 1H
(U/F) o Water thermo
switch OV Radiator temp.:
above 17°C (63°F)
11 o Electrical load control unit E/L switch ON: below 2.5V
E/L switch OFF: approx. 10—12V
Electrical load: Rear defroster switch
Headlight switch Blower motor switch (3rd & 4th position) Electrical fan switch
1J — — — — —
1K o P/S pressure
switch
Constant approx.
12V
P/S ON: below 2.5V P/S OFF: approx. 12V
1L o A/C switch A/C switch ON: below 2.5V A/C switch OFF: aDDrox. 12V Blower motor: ON
1M o Distributor
(Ne signal) OV or 5V Approx. 2.0V
1N o Distributor (G signal) OV or 5V Approx. 1.2V
Note
Terminals labeled "U/F" are only for unleaded fuel.
4C-99

4C CONTROL SYSTEM
Terminal Input Output Connection to Voltage (After warming-up) Remark Terminal Input Output Connection to Ign: ON Idle Remark
10 o Air flow sensor
(Burn-off control) Below 2.5V White burning off:
Approx. 8—12V
1P o
Control relay (Power supply circuit) Below 2.5V Ignition switch OFF:
Approx. 12V
1Q 0 Control relay (Fuel pump circuit) Approx. 12V Below 2.5V
1R
(L/F) O Knock sensor OV or 2—7V While knocking:
Approx. 0.001
1S — — — — —
1T o Ignition switch
(ON position) Approx. 12V
1U — — — — —
1V — — — — —
1W o Test connector Test connector grounded: OV Test connector not grounded: approx. 12V Green connector, 1-pin
1X o Igniter Approx. 12V *Approx.1V 'Engine Signal
Monitor: green and
red lights flash
2A (U/F) o V ref 4.5—5.5V
2B o Air flow sensor
(Ground) OV
2C — — Ground (E2) OV
2D (U/F) o Oxygen sensor OV 0-1.0V
• Cold engine: 0V at idle
• After warming-up: Increase engine speed: 0.7—1.0V Deceleration: 0—0.2V
2E o Air flow sensor
(Intake air mass) 1.0—1.6V 1.7—2.3V Increase engine speed: voltage increases
2F — — — .— —
2G (U/F) o Throttle sensor Accelerator pedal released: approx. 0.5V
Max. voltage (Throt-tle valve fully opened): approx. ,4.3V
2H (L/F) o Air flow sensor (Variable resister) 0-5V Depends on
adjustment
21 o Water thermo sensor Approx. 0.4V
Engine coolant
temp. 20°C (68°F):
approx. 2.5
2J o Intake air thermo sensor (Dynamic chamber)
Approx. 2.5V at 20°C (68°F)
2K o
Solenoid valve (Pressure regula-tor control)
For 120 sec. after ignition switch OFF - ON: below 2.5V
For 120. sec after starting: below 2.5V
During hot condi-tion: Coolant temp, above 70°C (158°F) Intake air temp, above 30°C (86°F) ...Unleaded fuel above 50°C (122°F) ...Leaded fuel
2K o
Solenoid valve (Pressure regula-tor control)
ADDrox. 12V Other conditions
2L — — — — —
Note
a) Terminal labeled "U/F" are only for unleaded fuel.
b)Terminal labeled "L/F" are only for leaded fuel.
4C-100

CONTROL SYSTEM 4C
Terminal Input Output Connection to Voltage (After warming-up) Remark Terminal Input Output Connection to Ign: ON Idle Remark
2M
(U/F) o Oxygen sensor
heater Below 2.5V Above 3000 rpm: Approx. 12V
2N
(U/F) o Solenoid valve (EGR) Below 2.5V
• Radiator temp, below 17°C (62.6°F) or cool-ant temp, below 70°C (158°F): constant below 2.5 V
• 1,500-3,500 rpm: approx. 12V
20 (U/F) 0 Solenoid valve (No.2 purge control) Approx. 12V
• Coolant temp, below 75 °C (167°F): constant approx. 12V
• During medium and high load of above 1,700 rpm: below 2.5V
2P
(U/F) o
Solenoid valve
(No.1 purge
control)
Below 2.5V
Coolant temp, below 70°C (158°F): ap-prox. 12V
2Q o Solenoid valve (Idle speed control) Approx. 9—11V
2R — — Ground (E02) OV
3A — — Ground (E01) OV
3B O Ignition switch
(Start position) Below 2.5V While cranking: ap-
Drox. 10V
3C o Injector (No.2) Approx. 12V *1 Approx. 12V
*1 Engine Signal Monitor green and red liahts flash
3D — — — — —
3E o Injector (No.1) Approx. 12V *1 Approx. 12V
*1 Engine Signal
Monitor: gree and
red liahts flash
3F 0 Injector (No.4) Approx. 12V *1 Approx. 12V
*1 Engine Signal Monitor: gree and red liahts flash
3G — Ground (E1) OV
3H o Injector (No.3) Approx. 12V 'Approx. 12V *1 Engine Signal
Monitor: green and
red lights flash
31 0 — Control relav ADDrox. 12V
3J — — Battery Approx. 12V For back-uD
76G04C-179
Note
Terminals labeled "U/F" are only for unleaded fuel.
Terminal Location
31 3G 3E 3C 3A
3J 3H 3F 3D 3B
2Q 2d 2M *
L CM
2G 2E 2C <
CM

2R 2P 2N 2L 2J 2H 2F 20 2B
1W 1U 1S 1Q 10 1M 1K 11 1G 1E 1C 1A
1X 1V 1T 1R 1P 1N 1L 1J 1H 1F 1D 1B
4C-101

CONTROL SYSTEM 4C
76G04C-203
76G04C-204
76G04C-205
G Signal Inspection
1. Remove the distributor. (Refer to section 5.)
2. Reconnect the distributor to the wiring harness.
3. Remove the rubber boot from the distributor con-
nector.
4. Connect a volt meter between the A terminal and
a ground.
5. Turn the shaft and check that the distributor gener-
ates one pulse signal I per one turn.
Ne signal Inspection
1. Remove the distributor. (Refer to Section 5.)
2. Reconnect the distributor to the wiring harness.
3. Remove the rubber boot from the distributor con-
nector.
4. Connect a voltmeter between the B terminal and
a ground.
5. Turn the shaft and check that the distributor gener-
ates four pulse signals per one turn.
Oxygen Sensor Heater
1. Disconnect the oxygen sensor connector.
2. Check resistance between terminals B and C.
Specification: approx. 6 Q
Knock Sensor (Leaded fuel)
1. Warm up the engine and rum it at idle.
2. Ground the test connector (Green, 1-pin) with a
jumper wire.
3. Tap the engine hanger with a hammer and verify
that the ignition timing retards.
4. If not correct, check the knock sensor.
76G04C-206
4C-109