temperature MAZDA 626 1987 Service Manual

4A CONTROL SYSTEM
ENGINE CONTROL UNIT
Check the engine control unit terminal voltages with
a voltmeter.
Caution
a) Warm up the engine before checking the
control unit.
b) If the proper voltage is not obtained, check
the wiring, connections and finally, check
the component.
FE and F8 Engine — ATX (ECE, Hong Kong, and Singapore)
Terminal
(Wire color) Connected to Condition Voltage

1A
(BW)
Ignition switch Ignition switch ON. Battery voltage

m
ST
'-O
Solenoid valve (Main
air
bleed control) Others Battery voltage
m
ST
'-O
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 (GO) Solenoid valve (Choke opener) Radiator coolant temperature below 17°C (63°F)
or
during cranking and
27
sec. after engine starts Below 1,5V
Others Battery voltage
1D
(GL)
Air bypass solenoid valve Idle switch OFF and engine speed above approx. 2,100 rpm Below 1,5V
Others Battery voltage
1E
— — —

1F
(G) Solenoid valve (Ignition timing control system)
Radiator coolant temperature above 17°C (63°F),
en-
gine coolant temperature below 72°C (162°F), inhibi-tor switch OFF and engine speed below 2,300
rpm

Below 1.5 V
Others Battery voltage
1G
— — —

1H
(LW) Solenoid valve (A/C) A/C switch
ON
and engine speed below approx. 2,300
rpm

Below 1,5V
Others Battery voltage
11
(YW) 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
Others Battery voltage
1J
(B)
Ground
—
Below 1,5V

9 MSSirSl
ivj
A 1
k *
76G04A-169
4A—86

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

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 1.5 V 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 OFF Below 1.5 V 2E
(RG)
Headlight switch
Headlight switch
ON
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 (In-
take manifold)
Engine coolant temperature below 72°C (162°F) Below 1,5V 2H
(L)
Water thermo switch (In-
take manifold) Engine coolant temperature above 72°C (162°F) Battery voltage
21
(LY)
Vacuum switch Vacuum less than 200 mmHg (7.9 inHg) Below 1.5V 21
(LY)
Vacuum switch
Vacuum more than 200 mmHg (7.9 inHg) Battery voltage
2J (RL) OD release solenoid valve Engine coolant temperature below 72°C (162°F) Below 1.5V 2J (RL) OD release solenoid valve
Engine coolant temperature above 72°C (162°F) Battery voltage
2K
(-)

— — -

2L (BR)
Inhibitor switch "N"
or "P"
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
(LsB) Idle switch Idling Battery voltage 2N
(LsB) Idle switch
Accelerator pedal depressed Below 1,5V

76G04A-170

{ 2M 2K 21
X
2F 2C
2A

2N 2L 2J 2H 2F 2D 2B
(11 X X
1C 1 A^j
1J 1H 1F 1D 1B

FE and F8 Engine — MTX (ECE, Hong Kong, and Singapore)
Terminal (Wire color) Connected to Condition Voltage

A
(RG) Headlight switch Headlight switch
ON
Below 1,5V A
(RG) Headlight switch
Headlight switch OFF Battery voltage
B
(B)
Ground
—
Below 1,5V

4A-87

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 IDLE-UP SYSTEM
COMPONENT DESCRIPTIONS
Component Function Remarks
Air bypass solenoid
valve

Controls bypass
air
amount Operates A: A/C
: ON

B: Intake
air
temp, high
or at
high
al-
titude C: P/S
:
ON, E/L applied
or
hot start

Air valve
When cold, supplies bypass
air
into
dy-

namic chamber
• Engine speed increased
to
shorten
warm-up period
• Bimetal type

Atmospheric pressure sensor

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

E/L control unit
Detects electrical load applied; sends sig-nal
to
engine control unit

Engine control unit
Detects signals from input sensors and switches; controls
air
bypass solenoid valve

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

P/S pressure switch
Detects P/S operation; sends signal
to
engine control unit P/S:
ON
when steering wheel turnefl right
or
left

76g04b-044
4B-36

4B IDLE-UP SYSTEM
AIR VALVE
Pre-inspection
1. Start the engine and run it at idle.
2. Pinch the bypass air hose and check that the en-
gine rpm drops.
When engine still cool RPM reduced
After warming-up RPM drop within
200 rpm
3. If the speed is not reduced when cold, check the
air valve, or check for vacuum leaks at the bypass
air hose.
4. If the speed drop is more than 200 rpm when
warm, check the air valve and current to the valve.
Inspection of Terminal Voltage
1. Disconnect the connector from the valve.
2. Remove the rubber boot from the connector.
3. Start the engine and run it at idle.
4. Check that there is battery voltage at terminal (WY),
using a voltmeter.
5. If not correct, check the circuit opening relay and
wiring harness.
76G04B-046
Inspection of Air Valve
1. Check the valve for operation.
Temperature 20°C (68°F) Valve open
(When engine cool)
After warming-up Valve closed
2. Replace valve if faulty.
76G04B-047
4B—38 expert22 Arm http://rutracker.org

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

4B FUEL SYSTEM
76G04B-061
I i. i { 1 t' i 1 I • i i 1 1 "1 —r
1 . . • , 1 ,
EDO 250
86U04A-074
w Test connector
(Yellow)
86U04A-075
Lever
To fuel pump To pulsation damper
FUEL PRESSURE
Note
a) When inspecting fuel pressure, use the
SST. (Refer to page 4B—47).
b)Warm up the engine to normal operating
temperature.
Injection Pressure
1. Set the lever on the adapter as shown in the figure.
2. Run the engine and measure the injection pres-
sure at various speeds.
Injection pressure: Approx. 235—275 kPa
(2.4—2.8 kg/cm2, 34—40 psi)
3. If not within specification, check the fuel pump pres-
sure and fuel line pressure.
Fuel Pump Pressure
1. Connect the terminals of the test connector (Yel-
low) with a jumper wire.
2. Turn the ignition switch ON to operate the fuel
pump.
3. Set the lever on the adapter as shown in the figure.
4. Check the fuel pump pressure.
Fuel pump pressure: 441—588 kPa
(4.5—6.0 kg/cm2, 64—85 psi)
5. If the fuel pump pressure is not within specifica-
tion, check the following;
No pressure
• Fuel pump operation (Refer to page
4B—49.)
Low pressure
• Fuel pump feeding capacity (Refer to
page 4B—50.)
High pressure
• Replace the fuel pump
6. After checking the fuel pump pressure, disconnect
the jumper wire from the test connector.
76G04B-062
4B—48