1987 MAZDA 626 Workshop Manual

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

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

SWITCH MONITOR FUNCTION 4C
Idle switch
76G04C-039
Blower switch
76G04C-040
Headlight switch
76G04C-041
Rear defroster switch
76G04C-042
4C—27

4C SWITCH MONITOR FUNCTION
Water thermo switch circuit
76G04C-043
4C-28

IDLE ADJUSTMENT 4C
Idle speed
Automatic
Control
Function
Engine Control Unit

IDLE
ADJUSTMENT
IDLE SPEED
The idle speed is controlled automatically by the
engine control unit through the idle speed con-
trol (ISC) solenoid valve, it is not necessary to
adjust the idle speed.
However, if the idle speed is not within specifi-
cation, the idle speed must be adjusted.
76G04C-044
Preparation
1) Check the condition of the engine (plugs, leaks in
hoses, etc.).
2) Make sure all accessories are OFF.
3) Warm up the engine and run it for three minutes
at 2,500—3,000 rpm in neutral.
4) Check the initial ignition timing and adjust it if
necessary.
76G04C-045
Inspection
1. Check that the idle speed is within specification
without grounding the test connector (Green,
1-pin).
Specification:
Applied load Idle speed
No load 750 ± 50 rpm
P/S load 750 ± 50 rpm
A/C and/or E/L load 800 ± 50 rpm
76G04C-046 2. If not correct, adjust the initial idle speed.
Adjustment
1. Ground the test connector (Green, 1-pin) with a
jumper wire.
2. Turn all accessories and loads OFF.
76G04C-047
4C—29

4C IDLE ADJUSTMENT
76G04C-048
Idle speed
Automatic
Control
Function
Engine Control Unit
76G04C-049
76G04C-050
3. Remove the blind cap and adjust the initial idle
speed to specification by turning the air adjust
screw.
Initial idle speed: 750 ± 50 rpm
4. After adjusting the idle speed, install the blind cap
and disconnect the jumper wire from the test con-
nector.
5. Recheck the idle speed.
6. If not within specification, check the idle speed con-
trol (ISC) system.
IDLE MIXTURE (Unleaded Fuel)
An automatic compensation function for air/fuel
mixture is built into the engine control unit, it
is not necessary to check and adjust the idle
mixture.
IDLE MIXTURE (Leaded Fuel)
Note
Before checking or adjusting the idle mixture,
check and adjust the idle speed, if necessary.
1. Insert a gas analyzer pick-up into the tail pipe.
2. Check that the CO and HC concentrations are with-
in specification.
CO concentration: 1.5 ± 0.5%
HC concentration: Less than 1,000 PPM
3. If the CO or HC concentration is not within specifi-
cation, turn the adjust screw
with
the SST to adjust.
76G04C-051
4C-30

INTAKE AIR SYSTEM 4C
INTAKE AIR SYSTEM
76G04C-052
This system controls the air required by the engine for operation. The system consists of the air duct,
resonance chamber, air cleaner, air flow sensor, throttle body, dynamic chamber, and intake manifold.
COMPONENT DESCRIPTION
Component Function Remark
Air cleaner Filters air entering throttle body Dry type
Air flow sensor Detects amount of intake air; sends signal to engine control unit Hot-wire type
Resonance chamber Minimizes intake air noise
Throttle body Controls intake air quantity Integrated throttle sensor and idle switch
4C—31