engine MAZDA 626 1987 Workshop Manual

TROUBLESHOOTING WITH SST 4B
Code No. 08 (Air flow meter) PC: Possible Cause

Are there poor connections
in air
flow meter circuit?

NO

Is there continuity between
air
flow meter and engine control unit?
Air flow meter Control unit

Vb
(RB wire) 31

Vc
(RW wire) 2B

Vs
(RB wire) 2E

E2
(LgY wire) 2C

YES

Is resistance
of air
flow meter OK?
Resistance:
Terminal More then
20

E2
Vs
20—400 20—1,000
E2
Vc
100-300
E2
Vb
200-400

YES
NO
NO
YES

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

VES

Are engine control unit terminal voltages OK? Check terminal: 2B, 2C, 2E,
31
(Refer
to
page 4B—89 and 4B—90)

YES
NO
NO

Repair
or
replace connector
PC: Open circuit
in
wiring harness from
air
flow
meter
to
engine control unit
Repair
air
flow meter
Air flow meter and circuit
OK

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

76g04b-010
4B—15

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. 15 (Oxygen sensor) PC: Possible Cause
Note
When Codes No.15 and 17 are present at the same time, first perform the checking proce-
dure for Code No.17. (Refer to page 4B—21.)
YES

PC: Engine control unit malfunction

76G04B-015
4B—20

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

SWITCH MONITOR FUNCTION 4B
SWITCH MONITOR FUNCTION
Individual switches can be monitored by the SST.
Note
The test connector must be grounded and the ignition switch ON (engine stopped).
Control unit
76G04B-022
Switch Self-Diagnosis Checker (Monitor lamp) Remarks Switch Light ON Light OFF Remarks

Clutch switch Pedal released Pedal depressed Gear:
IN

Neutral switch In gear Neutral Clutch pedal released
Idle switch Pedal depressed Pedal released
—

Brake light switch Pedal depressed Pedal released
—

A/C switch ON OFF Blower motor position:
"1"

position
Headlight switch ON OFF
—

Rear defroster switch ON OFF
—

Blower switch ON OFF Blower motor position:
"3"
or
"4"
position
Inhibitor switch D,
1, 2
and
R
range P and
N
range
—

Water thermo switch (Elec-trical fan) Terminal disconnected Terminal connected While fan
not
operating

4B-25

4B SWITCH MONITOR FUNCTION
49 H018 9A1
INSPECTION PROCEDURE
1. Warm up the engine to normal operating temper-
ature and stop it.
2. Connect the SST to the check connector (Green,
6-pin) and the negative battery terminal.
86U04A-034
76G04B-023
3. Connect a jumper wire between the test connec-
tor (Green, 1-pin) and a ground.
4. Turn the ignition switch ON. Check if monitor lamp
illuminates when each switch is made to function
as described below.
Caution
a) If any one of the switches is activated, the
monitor lamp will stay on.
b) Do not start the engine.
Note
The Digital Code Checker (49 G018 9A0) with
the Signal Adapter (49 9200180) may be used
in place of the Self-Diagnosis Checker.
Procedure
76G04B-024
4B—26