wiring MAZDA 626 1987 User Guide

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

TROUBLESHOOTING WITH SST 4B
Code No. 10 (Intake air thermo sensor) PC: Possible Cause

Are there poor connections
in air
flow meter circuit?

NO

Is there continuity between intake
air
thermo sensor (in
air
flow meter) and engine control unit?

YES

Intake
air
thermo sensor
(in
air
flow meter) Control unit
THA
(R
wire) 2J

E2
(LgY wire) 2C

NO

Repair
or
replace connector
PC: Open circuit
in
wiring harness from intake air thermo
sensor (in air flow meter)
to
engine control unit

YES

Is resistance
of
intake
air
thermo sensor (in
air
flow meter) OK?
Resistance:
Terminal Resistance
E2 <- THA -20°C
(
—4°F)
:
13.6-18.4
kfl
20°C
(
68°F)
:
2.21— 2.69
kfl
60°C (140°F)
:
493— 667
fl
NO
YES

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

YES

Are engine control unit
2J
and
2C
terminal voltages OK? (Refer
to
page 4B—89)

YES
NO
NO

Replace
air
flow meter
Intake
air
thermo sensor and circuit
OK

PC: Short circuit
in
wiring harness
PC: Engine control unit malfunction

76G04B-012
4B—17

TROUBLESHOOTING WITH SST 4B
Code No. 14 (Atmospheric pressure sensor) PC: Possible cause
YES

Is there continuity between atmospheric pressure
sensor
to
engine control unit?
Atmospheric pressure sensor Control unit
A (LgY wire) 2C
D
(Y
wire) 2H

NO
YES

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

YES

Are engine control unit
2C

OK? (Refer
to
page 4B—8<
and
2H
terminal voltages
3)

NO
NO

PC: Open circuit
in
wiring harness from atmospheric pressure sensor
to
engine control unit

YES

Atmospheric pressure sensor and circuit
OK

PC: Short circuit
in
wiring harness
PC: Engine control unit malfunction

76G04B-014
4B—19

4B TROUBLESHOOTING WITH SST
Code No. 25 (Solenoid valve-Pressure regulator) PC: Possible Cause

Is there battery voltage
at
(RB) wire
of
solenoid valve
connector?

NO
PC: Poor connection
of
connector
or
open circuit
in
wiring harness from (RB) wire
to
main relay (for engine control unit)

YES

PC: Poor connection
of
connector
or
open circuit
in
wiring harness from (RB) wire
to
main relay (for engine control unit)

YES
NO
Is there continuity
of
solenoid valve?
NO
Replace solenoid valve

YES

Is there continuity between solenoid valve and engine control unit?
Solenoid valve Control unit
B (WR wire) 2K

NO
PC: Open circuit
in
wiring harness from solenoid valve
to
engine control unit

YES
PC:
•
Short circuit
in
wiring harness • Engine control unit malfunction

76G04B-017
Code No. 26 (Solenoid valve-Purge)
YES
PC:
•
Short circuit
in
wiring harness • Engine control unit malfunction

76G04B-018
4B—22

TROUBLESHOOTING WITH SST 4B
Code No. 28 (Solenoid valve—EGR) PC: Possible Cause
VES

Is there continuity between solenoid valve and engine control unit?
Solenoid valve Control unit
B (WL wire) 2N

NO
PC: Open circuit
in
wiring harness from solenoid
valve
to
engine control unit

YES
PC:
•
Short circuit
in
wiring harness • Engine control unit malfunction

76G04B-019
Code No. 34 (Air bypass solenoid valve—Idle-up C)
YES
PC:
•
Short circuit
in
wiring harness • Engine control unit malfunction

76G04B-020
4B—23

4B TROUBLESHOOTING WITH SST
No. 35 Code (Air bypass solenoid valve—Idle-up B) PC: Possible Cause
YES
PC:
•
Short circuit
in
wiring harness • Engine control unit malfunction

76G04B-021
4B—24

IDLE-UP SYSTEM 4B
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensors or switch.
Possible
cause
\ Page
Symptom
Air valve
Air bypass solenoid valve Engine control unit
terminal
Possible
cause
\ Page
Symptom
Air valve
Idle-up singal Adjustment
Engine control unit
terminal
Possible
cause
\ Page
Symptom
Air valve
Idle-up singal Adjustment
1S 20
Possible
cause
\ Page
Symptom 4B—38 4B—39 4B—40 4B—89 4B—90
Engine
stalls
While warming up
1 2 3 4 5
Engine
stalls After warming up
1 2 3 4

Rough Idle
While warming up
1 2 3 4 5
Rough Idle After warming up
1 2 3 4

High idle speed after warming up
1 2 3 4 5

Runs rough on deceleration
1 2 3 4

Afterburn in exhaust system
1 2 3 4 5

Fails emission test
1 2 3 4 5

76G04B-045
4B-37

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

IDLE-UP SYSTEM 4B
AIR BYPASS SOLENOID VALVE
Inspection of Idle-up Signal
A/C
1. Warm up the engine and run it at idle.
2. Connect a voltmeter between terminal A and
ground.
3. Turn the A/C and blower motor switches ON.
4. Check that the meter shows battery voltage.
5. If not correct, check the A/C relay, A/C switch,
blower motor switch, fuse,and wiring harness.
76G04B-048
P/S
1. Warm up the engine and run it at idle.
2. Attach a voltmeter between the terminal F and
ground.
3. Turn the steering wheel all the way to either the
right or left.
4. Check that the meter shows OV.
5. Release the steering wheel.
6. Check that the meter shows battery voltage.
7. If not correct, check the P/S pressure switch (Re-
fer to page 4B—92) and wiring harness.
76G04B-049
High altitude compensation
1. Warm up the engine and run it at idle.
2. Connect a vacuum pump to the atmospheric pres-
sure sensor.
3. Connect a voltmeter between the terminals shown
in the following table and ground.
4. Apply vacuum to the atmospheric pressure sen-
sor as shown in the table using a vacuum pump.
5. Check that the voltmeter shows OV.
76G04B-050
J
O
6. Release the vacuum.
7. Check that the voltmeter shows battery voltage.
8. If not correct, check the atmospheric pressure sen-
sor (Refer to page 4B—99) and wiring harness.
Terminal Vacuum Amount

F Approx. 155 mmHg (6.10 inHg)
D Approx.
85
mmHg (3.35 inHg)

76G04B-051
4B-39

4B FUEL SYSTEM
TROUBLESHOOTING
Check
the
condition
of
the wiring harness and connectors before checking
the
sensors
or
switches.
Possible
cause
Page

V
S E
i
o

o V)
0
e
~
0)
Ju
»
•E
<»
CL
01
3
0
<0
1
£
Oxygen

sensor

s c V
in
V

P
o E k_

•E **
l_
h
O
v
w
Water
thermo
switch

Q.
E
3 Q.
u

Injector

£ 3 3 o d
aj
Engine
con-
trol unit terminal
< £
8
<
Q. Oxygen

sensor

£ t->
0)
>
M Water
thermo
switch
3
u.
Injector
3
u. 3C
3E
3B
Symptom 4B-94 4B-99 4B—98 4B-95 48—97 4B-97 4B-49 4B-S1 4B-48 4B-90 4B-90
Hard start
or
won't start (Cranks
OK)
5 4 1 3 2

Engine While warming
up
4 3 2 1 5

stalls After warming
up
1 3 2 4

Rough Idle While warming
up
4 3 2 1

Rough Idle After warming
up
1 2 4 3

Poor acceleration, hesitation,
or

lack
of
power
1 3 4 2

Runs rough
on
deceleration
1 2

Afterburn
in
exhaust system
1 2

Poor fuel consumption
5 6 4 3 2 1

Falls emission test
1 2

Engine stalls
or
rough after
hot
starting
1 3 2

76G04B-059
4B—44