1987 MAZDA 626 Workshop Manual

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

TROUBLESHOOTING WITH SST 4B
Code No. 17 (Feedback system) PC: Possible Cause
76G04B-016
4B-21

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