engine MAZDA 626 1987 Workshop Manual

TROUBLESHOOTING WITH SST 4C
49 H018 9A1
negative battery cable
^ll
Test connector: (Green, 1 pin)
86U04A-015

Ignition switch:
ON

for six
seconds
76G04C-014
2. Connect the SST to the check connector.
3. Ground the test connector (Green, 1-pin) with a
jumper wire.
4. Turn the ignition switch ON for six seconds (do
not start the engine).
5. Start and warm up the engine, then run it at 2,000
rpm for two minutes.
6. Verify that no code numbers are displayed.
PRINCIPLE OF CODE CYCLE
Malfunction codes are determined as shown below
86U04A-017
1. Code cycle break
The time between warning code cycles is 4.0 sec (the time the light is off).
ON
OFF
1 cycle Malfunction code
cycle break
4.0 sec.
86U04A-018
4C—13

TROUBLESHOOTING WITH SST 4C
Malfunction display
Sensor or subsystem Self-diagnosis Fail-safe Malfunction
code no. Malfunction code output signal pattern
Sensor or subsystem Self-diagnosis Fail-safe
08
Air flow sensor Open or short circuit Maintains basic sig-nal at preset value
09 o°pNp II IIL •
Water thermo sensor Open or short circuit Maintains constant 35°C (95°F) command
11 0°FNFJUUL
Intake air thermo sensor (dynamic chamber)
Short circuit Maintains constant 20°C (68°F) command
12
Throttle sensor Open or short circuit Maintains constant command of throttle valve fully open
15 ON n
OFF •L 01
Oxygen sensor Sensor output con-tinues less than 0.55V 120 sec. after engine starts (1,500 rpm or over)
Cancels
EG I
feed-
back operation
17 ON n
OFF L HI il
Feedback system Sensor output not changed 20 sec. af-ter engine starts (1,500 rpm or over)
Cancels
EG I
feed-
back operation
25 0°nfJU1LJIL
Solenoid valve (pres-sure regulator control)
Open or short circuit
26 2LMJIL
Solenoid valve (No.1 purge control)
Open or short circuit
27 ON nn
OFF | _ •111
-ii-Solenoid valve (No.2
purge control)
Open or short circuit
28 ON nn
OFF L Hi nr
Solenoid valve (EGR)
Open or short circuit
34 ^jmiHum
Solenoid valve (Idle speed control)
Open or short circuit
36 °FFJMI«U
Oxygen sensor relay
Open or short circuit
41 <£jimjiuM
Solenoid valve (Vari-able inertia control)
Open or short circuit
76G04C-018
Caution
a) If there is more than one failure present, the lowest number malfunction code is dis-
played first, the remaining codes are displayed sequentially.
b) After repairing a failure, turn off the ignition switch and disconnect the negative battery
cable and depress the brake pedal for at least 5 seconds to erase the memory of a mal-
function code.
4C—15

4C TROUBLESHOOTING WITH SST
Code No.2 (Ne signal) PC: Possible Cause
YES
PC: Engine control unit malfunction
76G04C-019
Code No.3 (G signal) PC: Possible Cause
4C-16

4C TROUBLESHOOTING WITH SST
Is there continuity between air flow sensor and
engine control unit?
Air flow sensor Engine control unit
D (RB wire) 2E
E (RW wire) 2B
NO
YES
Is there 12V at terminal B of air flow sensor connector? (Refer to page 4C—103)
YES
Is there continuity between terminal F of air flow sensor and ground? (Refer to page 4C-103)
YES
NO
NO
PC: Open circuit in wiring harness
PC: Open or short circuit in wiring harness from terminal B to control relay
PC: Open circuit in wiring harness
PC: • Engine control unit malfunction • Short circuit in wiring from terminal D of air flow sensor to engine control unit
76G04C-022
Code No. 09 (Water thermo sensor)
Are there poor connections in water thermo sensor circuit?
NO
Is there continuity between water thermo sensor and engine control unit?
YES
Is resistance of the water thermo sensor OK? Resistance:
YES
Water thermo sensor Enaine control unit
A (YB wire) 21
B (LgY wire) 2C
NO
Coolant temp Resistance
-20°C ( —4°F) 14.5-17.8 kfl
20°C ( 68°F) 2.2- 2.7 kfi
40°C {104°F) 1.0- 1.3 kfi
60°C (140°F) 500-640 fi
80°C (176°F) 280-350 fi
NO
YES
Is same Code No. present after performing after-repair procedure? (Refer to page 4C—12)
YES
Are engine control unit 21 and 2C terminal voltages OK? (Refer to page 4C—98)
YES
NO
NO
PC: Possible Cause
Repair or replace connector
PC: Open circuit in wiring harness from water thermo sensor to engine control unit
Replace water thermo sensor
Water thermo sensor and circuit OK
PC: Short circuit in wiring harness
PC: Engine control unit malfunction
76G04C-023
4C—18

TROUBLESHOOTING WITH SST 4C
No. 11 Code (Intake air thermo sensor) PC: Possible Cause
NO
Is there continuity between intake air thermo sensor
(dynamic chamber) and engine control unit?
Intake air thermo sensor (dynamic chamber) Engine control unit
A (RC wire) 2J
B (LgY wire) 2C
YES
Is resistance of intake air thermo sensor (dynamic chamber) OK? Resistance:
NO PC: Open circuit in wiring harness
Temperature Resistance
20°C (68°F) 29.7-36.3 kQ
50°C (122°F) 8.4-10.2 kQ
85°C (185°F) 2.5-3.1 kQ
NO Replace intake air thermo sensor (dynamic chamber)
YES
76G04C-024
Code No. 12 (Throttle sensor) PC: Possible cause
Next step
4C-19

TROUBLESHOOTING WITH SST 4C
Code No. 17 (Feedback system) PC: Possible Cause
Feedback system OK
76G04C-027
Code No. 25 (Solenoid valve-Pressure regulator control (PRC)) PC: Possible Cause
Repair or replace connector
Replace solenoid valve
76G04C-028
Warm up engine and run at 2,500—3,000 rpm for
three minutes Is Code No. still present?
Yes
Are there poor connections in solenoid valve circuit?
NO
Is there continuity of solenc )id valve?
YES
4C—21

4C TROUBLESHOOTING WITH SST
Code No. 26 (Solenoid valve—No. 1 purge control) PC: Possible Cause
YES
YES
Is there continuity between solenoid valve and engine control unit?
Solenoid valve Engine control unit
WG wire 2P
NO PC: Open circuit in wiring harness from solenoid valve to engine control unit
YES PC: • Engine control unit malfunction • Short circuit in wiring harness
76G04C-029
Code No. 27 (Solenoid valve—No. 2 purge control) PC: Possible Cause
Are there poor connections in solenoid valve circuit? YES Repair or replace connector
NO
NO Is there continuity of solenoid valve? NO Replace solenoid valve
YES
Is there battery voltage at RB wire of solenoid valve connector?
NO PC: Open circuit in wiring harness from RB wire to
control relay (for engine control unit)
YES
Is there continuity between solenoid valve and en-
gine control unit?
Solenoid valve Enaine control unit
WB wire 20
NO PC: Open circuit in wiring harness from solenoid valve to engine control unit
YES PC: • Engine control unit malfunction • Short circuit in wiring harness
76G04C-030
4C—22

TROUBLESHOOTING WITH SST 4C
Code No. 28 (Solenoid valve—EGR) PC: Possible Cause
Are there poor connections in solenoid valve circuit? YbS Repair or replace connector
NO
NO Is there continuity of solenoid valve? NO Replace solenoid valve
YES
Is there battery voltage of RB wire of solenoid valve connector?
NO PC: Open circuit in wiring harness from RB wire to control relay (for engine control unit)
YES
Is there continuity between solenoid valve and en-gine control unit?
Solenoid valve Engine control unit
WL wire 2N
NO^ PC: Open circuit in wiring harness from solenoid valve to engine control unit
YES PC: • Engine control unit malfunction • Short circuit in wiring harness
76G04C-031
Code No. 34 (Solenoid valve—Idle speed control (ISC)) PC: Possible Cause
YES PC: • Engine control unit malfunction • Short circuit in wiring harness
76G04C-032
4C-23

4C TROUBLESHOOTING WITH SST
No.36 Code (Oxygen sensor relay) PC: Possible Cause
YES
Is there continuity between Oxygen sensor relay engine control unit?
Oxygen sensor relay Engine control unit
RY 2M
NO^ PC: Open circuit in wiring harness from oxygen sensor relay to engine control unit
YES PC: • Engine control unit malfunction • Short circuit in wiring harness
76G04C-033
No.41 Code (Solenoid valve—Variable inertia control (VIC)) PC: Possible Cause
Are there poor connections in solenoid valve circuit? YES Repair or replace connector
NO
NO Is there continuity of VIC solenoid valve? NO Replace solenoid valve
YES
Is there battery voltage at RB wire of VIC solenoid valve connector?
NO PC: Open or short circuit in wiring harness from RG wire to control relay (for engine control unit)
YES
Is there continuity between VIC solenoid valve and engine control unit?
VIC solenoid valve Enaine control unit
L 1C
NO PC: Open circuit in wiring harness from VIC solenoid valve to engine control unit
YES PC: • Engine control unit malfunction • Short circuit in wiring harness
76G04C-034
4C—24

SWITCH MONITOR FUNCTION 4C
SWITCH MONITOR FUNCTION
Individual switches can be monitored by the SST (Self-Diagnosis checker 49 G018 9A0 or Digital
code checker 49 9200 180).
Note
The test connector must be grounded and the ignition switch ON (engine stopped).
Engine control unit
76G04C-035
Switch Self-Diagnosis Checker (Monitor lamp) Remark Switch Light ON Light OFF Remark
Clutch switch Pedal released Pedal depressed In gear
Neutral switch In gear Neutral Clutch pedal released
Idle switch Pedal depressed Pedal released —
Headlight switch ON OFF —
Rear defroster switch ON OFF —
Blower switch ON OFF Blower motor position: "3" or "4"
Water thermo switch (Elec-trical fan) Terminal disconnected Terminal connected While fan not operating
4C—25