MAZDA 626 1987 Workshop Manual

4C TROUBLESHOOTING GUIDE
The Troubleshooting Guide lists the systems most likely to cause
a
given symptom. After finding which
system(s)
to
check, refer
to the
pages shown
for
detailed guides.
iSystem
S UJ 1-tn > tn

INTAKE

AIR
SYSTEM
FUEL
SYSTEM

o oc a
_i o oc 1-z o o oc o i-<
-i
o UJ OC Ul oc 3 (0 tn Ul oc a.
IDLE

SPEED
CONTROL
(ISC)
SYSTEM
ELECTRONIC
SPARK
ADVANCE

(ESA)

CONTROL
SYSTEM

EXHAUST

GAS
RECIRCULATION

(EGR)

SYSTEM

EVAPORATIVE

EMISSION

CONTROL
(EEC)
SYSTEM
POSITIVE
CRANKCASE
VENTILATION
(PCV)
SYSTEM
DECELERATION
CONTROL
SYSTEM

EXHAUST

SYSTEM

VARIABLE

INERTIA
CONTROL
(VIC)
SYSTEM

Page

4C—31 4C—49 4C—68 4C—44 4C—75 4C—77 4C—80 4C—86 4C—72 4C—87
&
89
4C—39
2 3 2 — — 1 — — — — — —
3
4 3 — 1 — 2 — _ _ — — 3 5 4 — 2 — 3 — 1 — — —
4 5 4 -1 — 3 — 2 — — -4 6 5 — 2 — 3 4 1 — — —
o z 5 2 3 — 1 — — — — — — —
E o 6 3 4 — — — 1 2 — — 6 5
Q-E >> 7 4 3 — 2 — — — — 1 — —
(0 8 3 4 — 1 — — — — 2 — —
9 — 2 — — — 3 — — 1 5 4
10 — 2 1 — — — — — — — —
11 — — — — 1 — — — — — —
12 6 7 — 4 — 2 5 _ 3 1
76G04C-010
The numbers
of the
list show
the
priorities
of
inspections, from
the
most possible system
to
that with
the lowest possibility.
These were determined
on the
following basis:
• Ease
of
inspection
•
Most possible system
•
Most possible point
in
system
4C—10

TROUBLESHOOTING WITH SST 4C
TROUBLESHOOTING WITH SST
Engine control unit
76G04C-011
When troubles occur in the main input devices or output devices, check for the cause with the SST
(Self-Diagnosis checker 49 H018 9A1 or Digital code checker 49 G018 9A0 with Adaptor har-
ness 49 9200 180)
Failure of individual input and output devices is indicated and retrieved from the control unit as mal-
function code numbers.
Note
The control unit constantly checks for malfunction of the input devices. But, the control
unit checks for malfunction of output devices only in a 3 second period after the ignition
switch is turned ON and the test connector is grounded.
4C—11

4C TROUBLESHOOTING WITH SST
Check connector: (Green, 6 pin)
49 H018 9A1
86U04A-011
Test connector: (Green, 1 pin)'
INSPECTION PROCEDURE
1. Connect the SST to the check connector. (Green,
6-pin) and the negative battery terminal.
2. Set the select switch to position A.
Note
The check connector is located at the rear of
the left side wheel housing.
3. Ground the test connector (Green, 1-pin) with a
jumper wire.
Note
The test connector is located near the Self-
Diagnosis Checker check connector.
86U04A-012
OO
uu
SELF-DIAGNOSIS CHECKER
MONITOR LAMP SELECT SW «

o o o
o
76G04C-012
4. Turn the ignition switch ON.
5. Verify that 88 flashes on the digital display and that
the buzzer sounds for three seconds after turn-
ing the ignition switch ON.
6. If 88 does not flash, check the control relay (refer
to page 4C—96), power supply circuit, and check
connector wiring.
7. If 88 flashes and the buzzer sounds continuously
for more than 20 seconds check the check con-
nector wiring, then replace the engine control unit
and perform steps 3 and 4 again.
8. Note the code numbers and check for the causes
by referring to the check sequences shown on
pages 4C—16 to 4C—24. Repair as necessary.
Note
Cancel the code numbers by performing the
after-repair procedure after repairing.
AFTER-REPAIR PROCEDURE
1. Cancel the memory of malfunctions by disconnect-
ing the negative battery cable and depress the
brake pedal for at least five seconds.
76G04C-013
4C-12

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

4C TROUBLESHOOTING WITH SST
2. Second digit of malfunction code (ones position)
The digit in the ones position of the malfunction code represents the number of times the buzzer
is on 0.4 sec during one cycle.
ON
OFF
1 cycle Malfunction code
1 2 3 cycle break
Malfunction
code: 03
n^j
0.4 0.4 sdc. sec.
4.0 sec.
76G04C-015
3. First digit of malfunction code (tens position)
The digit in the tens position of the malfunction code represents the number of times the buzzer
is on 1.2 sec during one cycle.
It should also be noted that the light goes off for 1.6 sec. between the long and short pulses of
the buzzer.
1 cycle Malfunction code
1 2
~U 0.4
1.2 sec. sec h
1 2|
flfl
First digit
1.6 sec.
cycle break
Malfunction
code: 22
nr
4.0 sec.
Second
digit
76G04C-016
CODE NUMBER
Malfunction display
Sensor or
subsystem Self-diagnosis Fail-safe Malfunction
code no.
Malfunction code output signal pattern
Sensor or
subsystem Self-diagnosis Fail-safe
02 o°nfJLJJL
Ne signal No Ne signal from crank angle sensor during craking
03 oppJUllUl
G signal No G signal Cancels sequencial
injection
05
Knock sensor (only
leaded fuel)
Open or short circuit • Retards ignition timing 4°
76G04C-017
4C—14

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

TROUBLESHOOTING WITH SST 4C
76G04C-020
Code No.05 (Knock sensor) PC: Possible Cause
76G04C-021
Code No.08 (Air flow sensor) PC: Possible Cause
Next page
4C—17

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