1987 MAZDA 626 wiring

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

4C INTAKE AIR SYSTEM
REMOVAL
Caution
Before removing the following parts, release the fuel pressure from fuel system to reduce
the possibility of injury or fire. (Refer to page 4C—52.)
Remove in the sequence shown in the figure, referring to the removal note.
1. Air cleaner
2. Air flow sensor
3. Air hoses
4. Connectors (Idle switch,
ISC, Throttle sensor)
5. Water hoses
6. Vacuum hoses
7. Accelerator cable
8. Throttle body
9. Gasket
10. PCV hose
4C-32
11. Vacuum pipe assembly
(Unleaded fuel)
12. Dynamic chamber brackets
13. Connectors (Knock sensor,
Intake air thermo sensor)
14. Dynamic chamber
15. One-way check valve
16. Gasket
17. Wiring harness
(for injectors)
18. Fuel hoses
76G04C-053
19. Delivery pipe assembly
mounting bolt.
20. Heat insulator
21. Injectors
22. Delivery pipe assembly
23. EGR pipe
24. Intake manifold bracket
25. Solenoid valve
26. Intake manifold
27. Gasket
28. Air duct
29. Resonance chamber

7C VIC SYSTEM
COMPONENT DESCRIPTION
Component Function Remark
Dynamic chamber Provides chamber for VIC system operation Integrates one-way check valve
Engine control unit Monitors engine rpm, controls solenoid valve Unleaded fuel: ON at above 5200 rpm Leaded fuel: ON at above 5400 rpm
Intake manifold Provides short and long length of intake travel Integrates shutter valve
One-way check valve Holds vacuum in vacuum chamber Installed between dynamic chamber and vacuum chamber
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to control unit Installed in distributor
Solenoid valve (Vlfc) Controls vacuum to shutter valve actuator
Shutter valve Closes short intake port
Shutter valve actuator Actuates shutter valve according to
vacuum from solenoid valve
76G04C-066
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensor or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to pages 4C—10 and 11.)
Possible cause
\Page\.
Symptom
Vacuum chamber (Vacuum leak)
Shutter valve actuator
One-way check valve
Solenoid valve (VIC) Engine control unit (1C)
System
Inspection
Possible cause
\Page\.
Symptom
Vacuum chamber (Vacuum leak)
Shutter valve actuator
One-way check valve Vacuum ' Electric signal | signal
Engine control unit (1C)
System
Inspection
Possible cause
\Page\.
Symptom 4C—42 4C—41 4C—43 4C—42 4C-98 4C—41
Rough idle
During warm up 2 3 4 — — — 1 Rough idle After warming up 2 3 4 — — — 1
Poor acceleration, hesitation,
or lack of power 6 5 7 2 3 4 1
Poor fuel consumption 6 5 7 2 3 4 1
76G04C-067
4C—40

4C
ISC
SYSTEM
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensors or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to pages 4C—10 and 11.)
Possible cause
\Page
Symptom
Air valve P/S pres-sure switch
Solenoid
valve (Idle
speed
control)
Water
thermo
sensor
Engine control unit terminal System
In-
spection
Possible cause
\Page
Symptom
Air valve P/S pres-sure switch
Solenoid
valve (Idle
speed
control)
Water
thermo
sensor
1L 1W 2Q
System
In-
spection
Possible cause
\Page
Symptom 4C—47 4C—97 4C—48 4C—107 4C—98 4C—46
Engine
stalls
During warm up 2 — 3 4 — 5 6 1 Engine
stalls After warm up — 4 2 — 3 5 6 1
Rough
idle
During warm up 2 — 3 — — 4 5 1 Rough
idle After warm up 4 2 — 3 5 6 1
High idle speed after warm up 2 5 3 — 4 6 7 1
Runs rough on deceleration — — 2 — — 3 4 1
Afterburn in exhaust system 2 — 3 — — 4 5 1
Falls emission test 2 3 — — 4 5 1
76g04c-079
System Inspection
(Air valve)
1. Ground the test connector (Green, 1-pin) with a
jumper wire.
2. Disconnect the ISC valve connector (Gray, 2-pin)
at idle while the engine is cold.
3. Note the engine speed and reconnect the con-
nector.
4. Warm up the engine to the normal operating tem-
perature and disconnect the connector again.
5. Check that the engine speed is lower than that
when cold.
4C—46

FUEL SYSTEM
4C

TROUBLESHOOTING
Checking the condition of the wiring harness and connectors before checking the sensors or switches.
Note
If
no
problem
is
found, continue with inspection
of the
next system
of
Troubleshooting
Guide. (Refer
to
page 4C—10,
and 11)

Possible cause 0 CO £ O ** CO £ O "5
Page


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S o c
w O M C
.fc <0 "o
^ o w c 0) <0 c « o>
Im O CO c w w
0>
!
41 10 o E k 0) £ **
d>
5 <0 O E ^ 0) £
w 0

Fuel
pump
Injector Fuel
pressure

Engine control
unit terminal
a. E 3 a
a> » c

Transfer

pump

sv
(4WS)
ha c o o
if Qj
«> S£

< g. X O £ 1-ID a 5
Fuel
pump
Injector Fuel
pressure

1Q 3C,3E 3F,3H 3B ID k_ H
Transfer

pump

sv
(4WS) 3
C
U.
3

Symptom *C—103 4C—110 4C—107 4C—104 4C—107 4C—106 4C-56 4C-57 4C-54 4C-98 40-59
Hard start
or
won't start (Cranks
OK)
— — —-— g — 1 7 — 2 8 6 3 4 5
Engine During warm
up
4 — — — 3 — — 2 1 — 5 — — — —
stalls After warm
up
1 — — — — — — 3 2 — 4 — — — —
Rough During warm
up
5 — — — 3 — — 2 1 — 4 — — — —
a> 3 Idle After warm
up
1 6 — — 4 — — 3 2 — 5 — — — —
•o a> •o (0 a> c -»
Poor acceleration, hesi-tation,
or
lack
of
power 1 — — 3 5 — — 4 2 — 6 — — — — •o a> •o (0 a> c -» Runs
rough on
deceleration 1 — — — — — — 2 — — 3 — — — —
Afterburn on deceleration 1 — — — — — — 2 — — 3 — — — —
Poor fuel consumption 6 — 5 — 4 — — 2 1 — 3 — — — —
Engine stalls
or
runs rough after hot starting 1 5 — — — — — 3 2 — 4 — — — —
Falls emission test — — 1 — — 2 — 3 — — 4 — — — —
Hard start
or
won't
start (Cranks
OK)
— — — — 9 — 1 7 — 2 8 6 3 4 5
Engine During warm
up
4 — — — 3 — — 2 1 — 5 — — — —
stalls After warm
up
1 — — — — — — 3 2 — 4 — — — —
Rough During warm
up
— — — 3 — — 2 1 — 4 — — — —
a> 3 Idle After warm
up
1 6 — — 4 — — 3 2 — 5 — — — —
•o a> •o a
Poor acceleration, hesi-tation,
or
lack
of
power 1 — — — 4 — — 3 2 — 5 — — — —
a> Runs rough on deceleration 1 — — — — — — 2 — — 3 — — — —
Afterburn on deceleration 1 — — — — — — 2 — — 3 — — — —
Poor fuel consumption 5 — — — 4 — — 2 1 — 3 — — — —
Engine stalls
or
runs rough after
hot
staring 1 5 — — — — — 3 2 — 4 — — — —
Falls emission test 1 ?
76G04C-089
4C—51

4C FUEL SYSTEM
76G04C-103
76G04C-104
76G04C-105
- s A Test connector I \ (Yellow)
4. Disconnect the connector from each injector
respectively.
5. Check that the engine speed decreases about
100—200 rpm each time.
6. If not correct, check the following:
No operating sound and no speed drop
Check injector wiring harness
No speed drop only
Injector resistance
Injection volume of injector
Inspection
Perform the following inspections.
Resistance
1. Remove the injectors from the engine. (Refer to
page 4C—61.)
2. Check the resistance of each injector with an
ohmmeter.
3. If not correct, replace the injector.
Resistance: 12—16 Q
Fuel leakage test and volume test
1. Remove the injectors and delivery pipe. (Refer to
pages 4C—61 and 63.)
2. Affix the injectors to the delivery pipe with wire.
Caution
Affix the injectors firmly so that no movement
is possible.
Warning
Be extremely careful when working with fuel.
Always work away from sparks or open
flames.
3. Connect the terminals of the test connector (Yel-
low) with a jumper wire. Turn the ignition switch ON.
4. Check that no fuel leaks from the injector nozzles.
Note
After 1 minute, a drop of fuel from the injec-
tor is acceptable.
76G04C-106
4C—58

FUEL SYSTEM 4C
76G04C-112
86U04B-083
76G04C-113
Transfer Pump
1. Remove the fuel tank. (Refer to page 4C—65.)
2. Disconnect the fuel hoses from the transfer pump.
3. Remove the transfer pump.
4. Install in the reverse order of removal.
Injector
1. Remove the engine hanger.
2. Remove the wiring harness bracket.
3. Disconnect the PCV valve and hose from the dy-
namic chamber.
76G04C-114
4C-61

PRC SYSTEM 4C
COMPONENT DESCRIPTION
Component Function Remark
Engine control unit Detects signals from input sensors and switches; con-trols solenoid valve (Pressure regulator control)
Ignition switch
(ST position)
Sends engine cranking signal to engine control unit
Intake air thermo sensor Detects intake air temperature; sends signal to engine control unit
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Pressure regulator Adjusts fuel pressure supplied to injectors
Solenoid valve (Pres-
sure regulator control)
Controls vacuum to pressure regulator Cuts vacuum when hot
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Idle switch Detects when throttle valve closed; sends signal to engine control unit ON at idle
76G04C-129
TROUBLESHOOTING
Check the condition of the wiring harness and connections before checking the sensors or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to pages 4C—10 and 11.)
Possible
\ cause
\ Page
Solenoid valve (Pres-sure regula-tor control)
Water thermo
sensor
Intake air
thermo
sensor
Engine con-trol unit terminal
System inspection Solenoid valve (Pres-sure regula-tor control) 2K
Symplon 4C—70 4C—107 4C-110 4C—98 4C—70
Engine stalls or runs rough after hot starting 2 3 4 5 1
76G04C-130
4C-69