1987 MAZDA 626 clutch

4C OUTLINE
COMPONENT LOCATION
Input and Output Devices
Solenoid Solenoid Idle valve valve switch /nnA
Solenoid
valve*1 Solenoid valve*1
'(No.1 purge control)
E/L control unit
Engine control unit
Control relay
Knock sensor*2
Water thermo
switch*1
Oxygen Distributor
sensor*1
Clutch switch
\ Oxygen sensor
\ relay*1
Solenoid valve*1 (EGR)
Solenoid valve (ISC)
Air flow sensor
Neutral switch
Water thermo sensor
*1...Unleade fuel only
*2...Leaded fuel only
76G04C-004
4C—4

TROUBLESHOOTING GUIDE 4C
TROUBLESHOOTING GUIDE
This troubleshooting guide shows the malfunction numbers and the symptoms of various failures.
Perform troubleshooting as described below.
Input sensors and switches
Possible cause
Page
Symptom and No. CO
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Fault Indicated by SST
Code No. 02 03 05 *i 08 09 11 12 *2 15 • 2 17 *2 25 26 *2 27 *2 28 • 2 34 36 • 2 41
Hard start or won't start
(Cranks OK)
Engine stalls
Rough
Idle
During warm up
After warm up
During warm up
After warm up
High idle speed after warm up
Poor acceleration, hesita-tion or lack of power
TROUBLESHOOTING PROCEDURE
Note
Code No. Is to quickly determine which system or unit may be at fault by use of the SST. (Self-Diagnosis Checker 49 H018 9A1 or Digital Code Checker 49 G018 9A0 with Adaptor harness 49 9200 180)
1st: Check input sensors and output solenoid valves with the SST. (Refer to
page
AC—11.)

2nd: Check other switches with the SST. (Refer to page AC—25.)
3rd: Check the following items:
Electrical system
1) Battery condition 2) Fuses
Runs rough on deceleration
Afterburn in exhaust
system
9
10
Poor fuel consumption
Engine stalls or runs
rough after hot starting
11
12
Knocking
Fuel system
1) Fuel level
2) Fuel leakage 3) Fuel filter 4) Idle speed (with test connec-tor grounded)
Engine
1) Compression 2) Overheating
Ignition system 1) Ignition spark
2) Ignition timing (with test connec-tor grounded)
Intake air system 1) Air cleaner element 2) Vacuum or air leakage 3) Vacuum hose routing 4) Accelerator cable
Others 1) Clutch slippage
2) Brake dragging
Fails emission test 4th: Check Fuel and Emission Control Systems. (Refer to page 4C—10.)
*1..
*2„
.Leaded fuel
.Unleaded fuel
76G04C-009
4C—9

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

4C SWITCH MONITOR FUNCTION
Check connector: (Green, 6 pin)'
N negative battery
ii cable
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
Test connector: (Green, 1 pin)
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 as 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.
76G04C-036
76G04C-037
Neutral and Clutch switch
4C—26

ISC SYSTEM 4C
COMPONENT DESCRIPTION
Component Function Remark
A/C switch Detects air conditioner operation; sends
signal to engine control unit Switch ON when air conditioner
operating
Air valve When cold, supplies bypass air into dy-namic chamber • Engine speed increased to shorten warm-up period • Thermo wax type
• Installed in BAC valve
Clutch switch Detects in-gear condition; sends signal to engine control unit Switch ON when clutch pedal released
E/L control unit Detects that E/L is being applied; sends
signal to engine control unit
Engine control unit Detects signals from input sensors and switches; controls solenoid valve (Idle speed control)
Idle switch Detects when throttle valve fully closed;
sends signal to engine control unit
Installed on throttle body
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Neutral switch Detects in-gear condition; sends signal to engine control unit
Switch ON when in gear
P/S pressure switch Detects P/S operation; sends signal to engine control unit Switch ON when steering wheel turned right or left
Solenoid valve (Idle speed control) Controls bypass air amount • Controlled by duty signal from engine control unit • Installed in BAC valve
• Operates idle-up
Test connector For initial idle speed adjustment • Gerrn, 1-pin
• Idle speed feedback control cancelled when connector grounded
Water thermo sensor Detects coolant temperature; sends
signal to engine control unit
76G04C-078
4C—45

4C FUEL SYSTEM
COMPONENT DESCRIPTION
Component Function Remark
Air flow sensor Detects amount of intake air;
sends signal to engine control unit
Clutch switch Detects in-gear condition; sends signal to engine control unit Switch ON when clutch pedal released
Engine control unit Detects signals from input sensors and switches; controls injector and fuel pump operations
Fuel filter Filters fuel
Fuel pump Provides fuel to injectors • Operates while engine running
• Installed in fuel tank
Fuel pump control unit (4WS) Monitors fuel level in left section; controls transfer pump operation
G signal pick-up Detects No.1 cylinder TDC; sends signal to engine control unit Installed in distributor
Idle switch Detects when throttle valve fully closed; sends signal to engine control unit Installed on throttle body
Ignition switch (ST position) Sends engine cranking signal to engine control unit
Injector Injects fuel into intake port • Controlled by signals from engine control unit • High-ohmic injector
Intake air thermo sensor Detects intake air temperature; send signal to engine control unit
Control relay Supplies electric current to injectors fuel pump and engine control unit
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Neutral switch Detects in-gear condition; sends signal to engine control unit
Switch ON when in gear
Oxygen sensor (Unleaded fuel) Detects oxygen concentration; sends signal to engine control unit
• Zirconia ceramic and platinum coating • Integrated heater coil
Pressure regulator Adjusts fuel pressure supplied to injectors
Pulsation damper Absorbs fuel pulsation
Throttle sensor Detects throttle valve opening angle;
sends signal to engine control unit
Installed on throttle body
Transfer pump (4WS) Pumps fuel from the left to the right side Controlled by fuel pump control unit
Transfer pump switch (4WS) Detects fuel level in left section;
sends signal to control unit
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Water thermo switch (Unleaded fuel) Detects radiator coolant temperature; sends signal to engine control unit ON: above 17°C (63°F)
76G04C-088
4C-50

CONTROL SYSTEM 4C
CONTROL SYSTEM
Throttle sensor
Solenoid Solenoid Idle valve valve switch (VIC) (PRC)
Solenoid
valve
control)*
Solenoid valve
'(No.1 purge control)*1
E/L control unit
Engine control unit
Control relay
Injector
Knock sensor* -
Water thermo
switch*1
"1...Unleaded fuel
*2...Leaded fuel
Oxygen Distributor Water thermo sensor*1 sensor
Clutch switch
Oxygen sensor
relay*1
Solenoid valve
(EGR)*1
/ Solenoid valve 7 (ISC)
Air flow sensor
Neutral switch
76G04C-166
The control system consists of the input devices and the engine control unit. The control unit controls
the fuel injection amount (EGI), fuel injection pressure, bypass air amount, ignition timing, switch moni-
tor function, and fail-safe function.
4C-91

4C CONTROL SYSTEM
RELATIONSHIP CHART
Output Devices
and
Input Devices (Unleaded fuel)
IGNITION SWITCH
(ON POSION) X X X X X O X X X X X X X X O
TEST CONNECTOR X X X O X X X X X X X X X O X
ELECTRICAL LOAD CONTROL UNIT X X X o X X X X X X X X X X X
P/S PRESSURE SWITCH X X X o X X X X X X X X X X X
A/C SWITCH X X X o X X X X X X X X O X X
IGNITION SWITCH
(STA POSITION) O O X o O X X X X O X X X O X
NEUTRAL
AND

CLUTCH SWITCH O X X o X X X X X X X X X X X
OXYGEN SENSOR o X X X X X X X X X X X X X X
WATER THERMO
SWITCH (RADIATOR) o X X X X X X X o X X X X X X
INTAKE
AIR

THERMO SENSOR X X X X X X X X X O X X X X X
WATER
THERMO SENSOR o X X o X X o o O O X X X O o
IDLE SWITCH o X X o X X X X X o X X X O X
THROTTLE SENSOR o X X X X X X X O X X X X o X
AIR FLOW SENSOR o X X X X X X o X X X X X o O
Ne SIGNAL o o X O o X X O O O o o X o O
G SIGNAL X O X X X X X X X X X X X X X

\
INPUT

DEVICE
OUTPUT
DEVICE
FUEL
INJECTION
AMOUNT FUEL

INJECTION

TIMING
AIR
VALVE

ISC
VALVE
FUEL
PUMP

CONTROL
MAIN
POWER
CONTROL
SOLENOID
VALVE
(No.1
PURGE)
SOLENOID
VALVE
(No.2
PURGE)
SOLENOID
VALVE
(EGR)
SOLENOID

VALVE

(PRESSURE

REGULATOR
CONTROL)
SOLENOID
VALVE

(VARIABLE

INERTIA
CONTROL)

OXYGEN

SENSOR
RELAY
I A/C

RELAY

IGNITER
AIR

FLOW
SENSOR
(BURN-OFF)
\
INPUT

DEVICE
OUTPUT
DEVICE
INJECTOR
BAC
VALVE

CONTROL
RELAY
SOLENOID
VALVE
(No.1
PURGE)
SOLENOID
VALVE
(No.2
PURGE)
SOLENOID
VALVE
(EGR)
SOLENOID

VALVE

(PRESSURE

REGULATOR
CONTROL)
SOLENOID
VALVE

(VARIABLE

INERTIA
CONTROL)

OXYGEN

SENSOR
RELAY
I A/C

RELAY

IGNITER
AIR

FLOW
SENSOR
(BURN-OFF)

76G04C-167
4C—92