engine coolant MAZDA 626 1987 Repair Manual

4A CONTROL SYSTEM
Terminal (Wire color) Connected to Condition Voltage

C (BL) Rear defroster switch Rear defroster switch
ON
Below 1,5V C (BL) Rear defroster switch
Rear defroster switch OFF Battery voltage
D
(LG) A/C switch A/C operated Below 1,5V D
(LG) A/C switch
A/C not operated Battery voltage
E (LY) Solenoid valve (Main
air
bleed control) Intake manifold vacuum more than 300 mmHg (11.8 inHg), and radiator coolant temperature above 17°C (63 °F)
Battery voltage E (LY) Solenoid valve (Main
air
bleed control)
Others Below 1,5V
F
(GW)
Water thermo switch
(Radiator) Radiator coolant temperature below 17°C (63°F) Below 1,5V F
(GW)
Water thermo switch
(Radiator) Radiator coolant temperature above 17°C (63°F) Battery voltage
G (YL)
Ignition coil Ignition switch
ON or
engine running Battery voltage
H
(L)
Water thermo switch (Intake manifold) Engine coolant temperature below 72°C (162°F) Below 1,5V H
(L)
Water thermo switch (Intake manifold) Engine coolant temperature above 72°C (162°F) Battery voltage
J (BW) Ignition switch Ignition switch
ON
Battery voltage
K (GO) Solenoid valve (Choke opener) Radiator temperature below 17°C (63°F)
or
during cranking and
27
sec. after engine starts Below 1,5V K (GO) Solenoid valve (Choke opener)
Others Battery voltage
L (LsB) Idle switch Idling Battery voltage L (LsB) Idle switch
Accelerator pedal depressed Below 1,5V
M
(GL)
Air bypass solenoid valve Idle switch OFF and engine speed above approx. 2,100 rpm Below 1,5V M
(GL)
Air bypass solenoid valve
Others Battery voltage
0
(BY)
Ignition switch
(START position)
Ignition switch
ON
Below 1,5V 0
(BY)
Ignition switch
(START position) Cranking Battery voltage
P
(LW) Solenoid valve (A/C) A/C switch
ON
and engine speed below approx.
2,300
rpm

Below 1,5V P
(LW) Solenoid valve (A/C)
Others Battery voltage
Q (YW) Idle-up solenoid valve Headlight switch ON, rear defroster switch ON,
fan
speed control switch
is
3rd
or
4th position, A/C oper-ated,
or
engine coolant temperature below 72°C (162°F)
Below 1,5V Q (YW) Idle-up solenoid valve
Others Battery voltage
R
(LB)
Fan speed control switch Fan speed control switch
in
3rd
or
4th position Below 1,5V R
(LB)
Fan speed control switch
Fan speed control switch OFF Battery voltage

76G04A-171

f ° O M K I G E C
R P N L J H F D B

4A-88

CONTROL SYSTEM 4 A
FE and F8 Engine — ATX (General)
Terminal (Wire color) Connected to Condition Voltage

1A
(BW)
Ignition switch Ignition switch
ON
Battery voltage
1B (GR) Solenoid valve (Main
air
bleed control) Others Battery voltage 1B (GR) Solenoid valve (Main
air
bleed control) Radiator coolant temperature below 17°C (63°F)
or
intake manifold vacuum more than 200 mmHg (7.9 inHg)
Below 1,5V
1C
— — —

1D
— — —

1E
— — —

1F
— --

1G
-—

1H
(LW) Solenoid valve (A/C) A/C operated Below 1,5V 1H
(LW) Solenoid valve (A/C)
Others Battery voltage
11
(LW) Idle-up solenoid valve Inhibitor switch OFF and, headlight switch ON, rear defroster switch ON, fan speed control switch
is 3rd
or 4th position, A/C operated,
or
engine coolant tem-perature below 72°C (162°F)
Below 1,5V 11
(LW) Idle-up solenoid valve
Others Battery voltage
1J
(B)
Ground
—
Below 1.5V
2A (YL) Ignition coil Ignition switch
ON or
engine running Battery voltage
2B (LB) Fan speed control switch Fan speed control switch
in
3rd
or
4th position Below 1.5V 2B (LB) Fan speed control switch
Fan speed control switch OFF Battery voltage
2C
(BL)
Rear defroster switch Rear defroster switch
ON
Below 1,5V 2C
(BL)
Rear defroster switch
Rear defroster switch OFF Battery voltage
2D
(LG) A/C switch A/C operated Below 1,5V 2D
(LG) A/C switch
A/C not operated Battery voltage
2E
(RG)
Headlight switch Headlight switch
ON
Below 1,5V 2E
(RG)
Headlight switch
Headlight switch OFF Battery voltage
2F
(GW)
Water thermo switch
(Radiator)
Radiator coolant temperature below 17°C (63°F) Below 1.5V 2F
(GW)
Water thermo switch
(Radiator) Radiator coolant temperature above 17°C (63°F) Battery voltage
2G
— — —

2H
(L)
Water thermo switch
(Intake manifold) Engine coolant temperature below 72°C (162°F) Below 1,5V 2H
(L)
Water thermo switch
(Intake manifold) Engine coolant temperature above 72°C (162°F) Battery voltage
21 (LB)
Vacuum switch Vacuum less than 200 mmHg (7.9 inHg) Below 1.5V 21 (LB)
Vacuum switch
Vacuum more than 200 mmHg (7.9 inHg) Battery voltage
2J
(RL)
OD release solenoid Engine coolant temperature below 72°C (162°F) Below 1,5V 2J
(RL)
OD release solenoid
Engine coolant temperature above 72°C (162°F) Battery voltage

4A-89

4A CONTROL SYSTEM
Terminal
(Wire color) Connected to Condition Voltage

2K
— — —

2L
(BR) Inhibitor switch "P"
or "N"
range Below 1,5V 2L
(BR) Inhibitor switch
Others Battery voltage
2M
(BY)
Ignition switch
(START position)
Ignition switch
ON
Below 1,5V 2M
(BY)
Ignition switch
(START position) Cranking Battery voltage
2N
— — —
76G04A-172
(2M X
2
X
2F 2C

X 2L
2J 2H 2F 2D 2B

fll X >< X

1J 1H
>< X
1B

FE and F8 Engine — MTX (General)
Terminal (Wire color) Connected to Condition Voltage

A
(W)
Headlight switch Headlight switch
ON
Below 1,5V A
(W)
Headlight switch
Headlight switch OFF Battery voltage
B
(B)
Ground
—
Below 1,5V
C
(BL) Rear defroster switch Rear defroster switch
ON
Below 1,5V C
(BL) Rear defroster switch
Rear defroster switch OFF Battery voltage
D
(LG) A/C switch A/C operated Below 1.5V D
(LG) A/C switch
A/C not operated Battery voltage
E
(LB) Solenoid valve (Main
air

bleed control)
Intake manifold vacuum more than 300 mmHg (11.8 inHg), and radiator coolant temperature above 17°C (63 °F)
Battery voltage E
(LB) Solenoid valve (Main
air

bleed control)
Others Below 1.5V
F
(GW)
Water thermo switch
(Radiator)
Radiator coolant temperature below 17°C (63°F) Below 1,5V F
(GW)
Water thermo switch
(Radiator) Radiator coolant temperature above 17°C (63°F) Battery voltage
G (YL)
Ignition coil Ignition switch
ON or
engine running Battery voltage
H
(L)
Water thermo switch (Intake manifold) Engine coolant temperature below 72°C (162°F) Below 1,5V H
(L)
Water thermo switch (Intake manifold) Engine coolant temperature above 72°C (162°F) Battery voltage
I
— — —

J
(BW)
Ignition switch Ignition switch
ON
Battery voltage
K
— —

L
— — —

M
— — —

N
— —
4A-90

CONTROL SYSTEM 4 A
Terminal (Wire color) Connected to Condition Voltage

0 (BY)
Ignition switch*
(START position) Ignition switch
ON
Below 1.5V 0 (BY)
Ignition switch*
(START position) Cranking Battery voltage
P
(LW) Solenoid valve (A/C) A/C switch
ON
and engine speed below approx.
2,300
rpm
Below 1,5V
Others Battery voltage
Q (YW) Idle-up solenoid valve Headlight switch ON, rear defroster switch ON,
fan
speed control switch
is
3rd
or
4th position, A/C oper-ated,
or
engine coolant temperature below 72°C (162°F)
Below 1,5V
Others Battery voltage
R
(LB)
Fan speed control switch Fan speed control switch
in
3rd
or
4th position Below 1,5V R
(LB) Fan speed control switch OFF Battery voltage
*
Not
used
76G04A-173

{
Q
0
><
K
X
G E C A
^

R P
R X
J H F D B

FE 8Valve — Unleaded Fuel
Terminal (Wire color) Connected to Condition Voltage

A
(L)
Coast enrichment solenoid valve Engine speed approx. 1,500—2,300 rpm and idle switch
ON

Below 1,5V A
(L)
Coast enrichment solenoid valve
Others Battery voltage
B
(B)
Ground
—
Below 1,5V
C (LB)
Air bypass solenoid valve Engine speed above approx. 3,500 rpm and idle
switch
ON

Below 1,5V C (LB)
Air bypass solenoid valve
Others Battery voltage
D
(YL)
Ignition coil Ignition switch
ON or
engine running Battery voltage
E
— — —

F
(BW)
Ignition switch Ignition switch
ON
Battery voltage
G (YW) Slow fuel cut solenoid valve Engine speed above approx. 2,300 rpm and idle
switch
ON

Battery voltage G (YW) Slow fuel cut solenoid valve
Others Below 1.5V
H
(LW) A/C switch A/C operated and engine speed above approx.
1,500 rpm
Battery voltage H
(LW) A/C switch
A/C not operated
or
engine speed below approx.
1,500 rpm
Below 1,5V

4A—91

4B TROUBLESHOOTING WITH SST
Code No. 09 (Water thermo sensor) PC: Possible Cause

Are there poor connections
at
water thermo sensor circuit?

NO
YES
Repair
or
replace connector
Is there continuity between water thermo sensor and control unit?
Water thermo sensor Control unit
A (YB wire) 21
B (LgY wire) 2C

YES

Is resistance
of
the water thermo sensor OK? Resistance:
Coolant temp Resistance
-20°C
(
-4°F) 14.5-17.8 k£2
20°C
(
68°F) 2.2- 2.7
kQ

40°C (104°F) 1.0- 1.3
kfi

60°C (140°F) 500—640
Q

80°C (176°F) 280-350
Q
NO
PC: Open circuit
in
wiring harness from water thermo sensor
to
engine control unit

NO
Replace water thermo sensor

| YES

Is same Code No. present after performing after-
repair procedure? (Refer
to
page 4B—10)

YES

Are engine control unit
21
OK? (Refer
to
page 4B—8
and
2C
terminal voltages
3)

NO
Water thermo sensor and circuit
OK
NO
PC: Engine short circuit
in
wiring harness

YES

PC: Engine control unit malfunction

76G04B-011
4B—16

FUEL SYSTEM 4B
COMPONENT DESCRIPTIONS
Component Function Remarks
Air flow meter
Detects amount
of
intake
air;

sends signal
to
engine control unit Intake
air
thermo sensor and fuel pump
switch
are
integrated

Atmospheric pressure sensor
Detects atmospheric pressure; sends sig-nal
to
engine control unit

Circuit opening relay
Voltage
for
fuel pump while engine running

Clutch switch
Detects in-gear condition; sends signal
to
engine control unit Switch
ON
when clutch pedal released

Engine control unit
Detects signals from input sensors and switches; controls injector operation

Fuel filter
Filters particles from fuel

Fuel pump
Provides fuel
to
injectors • Operates while engine running
• Installed
in
fuel tank

Idle switch
Detects when throttle valve fully closed;
sends signal
to
engine control unit
Installed
in
throttle sensor

Ignition coil (-) terminal
Detects engine speed; sends signal
to
engine control unit

Ignition switch (ST position)
Sends engine cranking signal
to
engine control unit

Inhibitor switch
Detects in-gear condition; sends signal
to
engine control unit
Switch
ON in "N" or "P"
range

Injector
Injects fuel into intake port • Controlled
by
signals from engine control unit • High-ohmic injector

Intake air thermo sensor
Detects intake
air
temperature;
sends signal
to
engine control unit Installed
in air
flow meter

Main relay
Supplies electric current
to
injectors and engine control unit

Neutral switch
Detects in-gear condition; sends signal
to
engine control unit
Switch
ON
in-gear

Oxygen sensor
Detects Oxygen concentration; sends sig-nal
to
engine control unit
Zirconia ceramic and platinum coating

Pressure regulator
Adjusts fuel pressure supplied
to
injectors

Pulsation damper
Absorbs fuel pulsation

Throttle sensor
Detects throttle valve opening angle; sends signal
to
engine control unit
Integrated idle switch

Water thermo sensor
Detects coolant temperature;
sends signal
to
engine control unit

Water thermo switch
Detects radiator coolant temperature; sends signal
to
engine control unit ON: above 17°C (63°F)

76G04B-058
4B—43

FUEL SYSTEM 4B
PRESSURE REGULATOR CONTROL SYSTEM
Water thermo sensor
*
Fuel
(To fuel tank)
76G04B-072
To prevent percolation of the fuel during idle after the engine is restarted, vacuum is cut to the pres-
sure regulator, increasing the fuel pressure.
Specified time: Approx. 120 sec.
Operating condition: Coolant temperature — above 70°C (158°F)
Intake air temperature — above 10°C (50°F)
4B—53

4B FUEL SYSTEM
COMPONENT DESCRIPTIONS
Component Function Remarks
Engine control unit Detects signals from input sensors and
switches; controls solenoid valve (Pres-
sure regulator control)
Idle switch Detects when throttle valve fully closed; sends signal to engine control unit Installed in throttle sensor
Ignition coil (-) terminal Detects engine speed; sends signal to engine control unit
Ignition switch
(ST position)
Sends engine cranking signal to engine control unit
Intake air thermo sensor Detects intake air temperature; sends signal to engine control unit
Installed in air flow meter
Pressure regulator Adjusts fuel pressure supplied to injectors
Solenoid valve (Pres-sure regulator control) Controls vacuum line to pressure regulator Closes vacuum line when hot
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
76G04B-073
4B—54

4B DECELERATION CONTROL SYSTEM
DECELERATION CONTROL SYSTEM
This system consists of the dashpot and fuel cut system. The dashpot is to prevent after-burn so that
the throttle valve gradually closes during deceleration.
The control unit detects engine deceleration judging from the engine speed and the idle switch, and
signals a fuel cut operation to match the engines need, based on the coolant temperature and the
driving condition.
4B—64

DECELERATION CONTROL SYSTEM 4B
COMPONENT DESCRIPTIONS
Component Function Remarks
Brake light switch Detects braking operation (deceleration);
sends signal to engine control unit
Clutch switch Detects in-gear condition;
sends signal to engine control unit Switch ON when clutch pedal released
Dashpot (MTX) Prevents sudden closing of throttle valve during deceleration or shifting Adjustment speed: 1,900—2,100 rpm
Engine control unit Detects signals from input sensors and switches; cuts fuel injection
Idle switch Detects when throttle valve fully closed; sends signal to engine control unit Installed in throttle sensor
Ignition coil (-) terminal Detects engine speed; sends signal to engine control unit
Neutral switch Detects in-gear condition; sends signal to engine control unit Switch ON when in-gear
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Water thermo switch Detects radiator coolant temperature; sends signal to engine control unit ON: above 17°C (63°F)
76G04B-089
4B—65