light MAZDA 626 1987 Service Manual

4B IDLE-UP SYSTEM
76G04B-052
76G04B-053
76G04B-054
Hot idle compensation
1. Warm up the engine and run it at idle.
2. Connect a voltmeter between the terminal F, D and
ground.
3. Remove the air cleaner upper case assembly.
4. Heat the intake air thermo sensor to more than
55°C
(131
°F).
5. Check that the meter shows OV.
6. If not correct, check the intake air thermo sensor
(Refer to page 4B—94).
E/L (Electrical load)
1. Warm up the engine and run it at idle.
2. Connect a voltmeter between the F terminal and
ground.
3. Apply the E/L.
E/L:
• Headlight • Rear defroster
• Electrical fan motor
• Blower motor (3rd or 4th position)
4. Check that the meter shows OV.
5. If not correct, check the electrical load control unit
(Refer to page 4B—93).
Adjustment
1. Warm up the engine and run it at idle.
2. Turn all accessories OFF.
3. Connect a tachometer to the engine.
4. Disconnect the air bypass solenoid valve con-
nector.
5. Check the idle speed and adjust it if necessary.
6. Apply battery power to each BAT terminal and
ground each GRD terminal as shown in the table.
7. Check that the engine speed is within specification.
76G04B-055
Valve BAT GRD Engine speed

A (for A/C) A B 1,250—1,350
rpm

B (for high altitude and high intake
air
temp.) C D 900—1,000
rpm
(MTX)
1,000-1,100
rpm
(ATX)
C (for P/S, E/L, high intake
air
temp., high altitude and
hot
idle compensations)
E F
900—1,000
rpm
(MTX)
1,000-1,100
rpm
(ATX)

4B—40

DECELERATION CONTROL SYSTEM 4B
COMPONENT DESCRIPTIONS
Component Function Remarks
Brake light switch Detects braking operation (deceleration);
sends signal to engine control unit
Clutch switch Detects in-gear condition;
sends signal to engine control unit Switch ON when clutch pedal released
Dashpot (MTX) Prevents sudden closing of throttle valve during deceleration or shifting Adjustment speed: 1,900—2,100 rpm
Engine control unit Detects signals from input sensors and switches; cuts fuel injection
Idle switch Detects when throttle valve fully closed; sends signal to engine control unit Installed in throttle sensor
Ignition coil (-) terminal Detects engine speed; sends signal to engine control unit
Neutral switch Detects in-gear condition; sends signal to engine control unit Switch ON when in-gear
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Water thermo switch Detects radiator coolant temperature; sends signal to engine control unit ON: above 17°C (63°F)
76G04B-089
4B—65

4B PCV SYSTEM
POSITIVE CRANKCASE VENTILATION
(PCV)
SYSTEM
76G04B-106
The PCV valve is operated by the intake manifold vacuum.
When the engine is running at idle, the PCV valve is opened slightly and a small amount of blowby
gas is drawn into the dynamic chamber.
At high engine speeds, the PCV valve is further opened and a larger amount of blowby gas is drawn
into the dynamic chamber.
COMPONENT DESCRIPTION
Component Function
PCV valve Controls blowby gas amount pulled into engine
PCV VALVE
1. Warm up the engine to the normal operating tem-
perature and run it at idle.
2. Disconnect the PCV valve and the ventilation hose
from the cylinder head cover.
3. Close the PCV valve opening.
4. Check that vacuum is felt.
4B—80

CONTROL SYSTEM 4B
CONTROL SYSTEM
Atmospheric
pressue sensor
Engine control unit
Brake light switch
Clutch switch
Circuti opening
relay
E/L control unit
Air flow meter
Neutral switch
76G04B-129
The control system consists of the input devices and the engine control unit. The engine control unit
controls the fuel injection amount (EGI), fuel injection pressure, bypass air amount, switch monitor func-
tion, and fail-safe function.
4B—83

4B CONTROL SYSTEM
RELATIONSHIP CHART
Input Devices and Output Devices
BRAKE LIGHT SWITCH O X X X X X X X X X
ELECTRICAL LOAD CONTROL UNIT X X X X X X X X O X
P/S PRESSURE SWITCH* X X X X X X X X O X
A/C SWITCH O X X X X O O X X O
IGNITION SWITCH
(STA

POSITION) O O X O X X X X O O
INHIBITOR SWITCH o X X X O X X X X O
NEUTRAL
AND
CLUTCH SWITCH o X X X X X X X X O
OXYGEN SENSOR o X X X X X X X X X
WATER THERMO SWITCH (RADIATOR) o X X X O X X X X X
ATMOSPHERIC PRESSURE SENSOR o X X X X O X O O X
INTAKE
AIR
THERMO SENSOR o X X O X X X O O X
WATER THERMO SENSOR o X X O O O X X o X
IDLE SWITCH o o X O X X X X o X
THROTTLE SENSOR o O X X O X X X X O
AIR FLOW METER o X X X X O X X X X
IGNITION COIL o O X O O O X X o O

INPUT
DEVICES
OUTPUT
DEVICES
FUEL
INJECTION
AMOUNT FUEL
INJECTION

TIMING
PRESSURE
REGULATOR
EGR
PURGE
IDLE-UP
(A)*
IDLE-UP
(B)

IDLE-UP

(C)

rr

INPUT
DEVICES
OUTPUT
DEVICES
INJECTOR
AIR

VALVE
SOLENOID
VALVE
AIR

BYPASS
SOLENOID
VALVE
AIR

CONDITIONEI

76G04B-108
4B-84

4B CONTROL SYSTEM
Terminal Voltage
If the input and output devices and related wiring are normal, but the engine control unit terminal volt-
age is incorrect, replace the engine control unit.
Terminal Input Output Connection to Voltage (After warming-up) Remarks Terminal Input Output Connection to IGN: ON Idle Remarks
1A — — — — —
1B o Self-Diagnosis Checker (Code number)
For 3sec. after ignition switch OFF ->• ON: below 6.2V (Buzzer sounds) After 3sec.: Battery voltage (Buzzer does not sound)
• Using Self-Diagnosis Check-er and test con-nector grounded • Buzzer sounds: below 6.2V • Buzzer does not sound: Battery voltage
1C — — — — —
1D o Self-Diagnosis Checker (Monitor lamp)
Test connector grounded
For 3sec. after igni-tion switch OFF ON:
below 6.2V (light il-luminates) After 3sec.: Battery voltage (light does not illuminate)
(Test connector grounded) approx. 10V (Test connector not grounded) Monitor lamp ON: below 6.2V Monitor lamp OFF: Battery voltage
With Self-Diagnosis
Checker
1E O Idle switch Accelerator pedal released: below 1.5V
Accelerator pedal depressed: Battery voltage
1F o A/C relay A/C switch ON: below 2.5V A/C switch OFF: Battery voltage
Blower motor ON
1G — — — — —
1H o Water thermo switch Below 1,5V Radiator temp.:
above 17°C (63°F)
11 o Electrical load con-trol unit Electrical load ON: below 1.5V Electrical load OFF: Battery voltage Electrical load: Rear defroster Headlight Blower motor (3rd & 4th position) Electrical fan
1J o Brake light switch Brake pedal released: below 1.5V
Brake pedal depressed: battery voltage
1K — — — — — —
1L o A/C switch A/C switch ON: below 1.5V
A/C switch OFF: battery voltage
Blower motor: ON
1M o Ignition coil © terminal Battery voltage *1 Battery voltage *1 Engine Signal Monitor: green and red lights flash
1N — — — — —
10 — — — —
4B-88

4B CONTROL SYSTEM
Terminal Input Output Connection to Voltage (After warming-up) Remarks Terminal Input Output Connection to IGN: ON Idle Remarks
2N o Solenoid valve (EGR) Below 1,5V • Cold engine: be-low 1,5V Radiator coolant temp.—below 17°C (63°F) or Engine coolant temp.—below 70°C (158°F)
• Engine above ap-prox. 1,500 rpm: Battery voltage
20 o Air bypass solenoid valve (Idle-up B) Battery voltage While solenoid ON (Refer to page 4B-35): below 1.5 V
2P o Solenoid valve
(Purge control valve)
Battery voltage • Medium and high
load: below 1,5V
2Q — — — —
2R — — Ground (E02) Below 1,5V
3A — — Ground (E01) Below 1.5V
3B O Ignition switch (Start position) Below 1,5V While cranking: bat-
tery voltage
3C o Injector (No. 4 and No. 2) Battery voltage *1 Battery voltage *1 Engine Signal Monitor green and red lights flash
3D o Inhibitor switch "N" or "P" range: below 2.0V
Other ranges: battery voltage
ATX
3E o Injector (No. 1 and No. 3) Battery voltage *
1
Battery voltage *1 Engine Signal Monitor: green and red lights flash
3F -— — — —
3G — Ground (Ei) Below 1.5V
3H — — — —
31 o — Ma ri relay Battery voltage
3J — — Battery Battery voltage For back-up
76G04B-110
31 3G 3E 3C 3A
3J 3H 3F 3D 3B
2Q 20 2M 2K 21 2G 2E 2C 2A
2R 2P 2N 2L 2J 2H 2F 2D 2B
1W 1U 1S 1Q 10 1M 1K 11 1G 1E 1C 1A
1X 1V 1T 1R 1P 1N 1L 1J 1H 1F 1D 1B
4B—90

CONTROL SYSTEM 4B
Replacement
1. Disconnect the negative battery cable.
2. Remove the front console covers (right and left).
3. Disconnect the connectors from the control unit.
4. Replace the control unit.
NEUTRAL SWITCH
Inspection
1. Disconnect the neutral switch connector.
2. Connect an ohmmeter to the switch.
3. Check continuity of the switch.
Transmission Continuity
In neutral No
In other ranges Yes
4. After checking, connect the switch connector.
Note
Refer to section 7A for replacement of the
neutral switch.
CLUTCH SWITCH
Inspection
1. Disconnect the clutch switch connector.
2. Connect an ohmmeter to the switch.
3. Check continuity of the switch.
Pedal Continuity
Depressed No
Released Yes
4. After checking, connect the switch connector.
Note
Refer to section 6 for replacement of the
clutch switch.
BRAKE LIGHT SWITCH
Inspection
1. Disconnect the brake light switch connector.
2. Connect an ohmmeter to the switch.
3. Check the continuity of the switch.
Pedal Continuity
Depressed Yes
Released No
4. After checking, connect the switch connector.
Note
Refer to section 11 for replacement of the
brake switch.
4B-91

4B CONTROL SYSTEM
E/L CONTROL UNIT
Inspection
1. Connect a voltmeter between the E/L control unit
and ground.
2. Start the engine and check the terminal voltages
as described below.
69G04A-174
Terminal Input Output Connection to Voltage (after warm-up) Remarks Terminal Input Output Connection to Ignition switch: ON idle Remarks
A
(BW) — — Ignition switch Battery voltage
B — — — — — —
C
(B) — — Ground OV
D (LY) 0 Electrical fan relay
Battery voltage Coolant temp.: below 97°C (207°F) D (LY) 0 Electrical fan relay
Below 1,5V Coolant temp.:
above 97°C (207°F)
E
(GY) o Engine control unit
(11)
OV E/L: ON E
(GY) o Engine control unit
(11) Battery voltage E/L: OFF
F (RB) 0 Headlight switch
Battery voltage Headlight switch:
ON F (RB) 0 Headlight switch
Below 1,5V Headlight switch:
OFF
G (LB) 0 Blower motor switch
Below 1,5V Blower motor switch: ON (3rd or 4th position) G (LB) 0 Blower motor switch
Approx. 5V Others
H
(BL) 0 Rear defroster switch
Below 1,5V Rear defroster switch: ON H
(BL) 0 Rear defroster switch Battery voltage Rear defroster switch: OFF
76G04B-131
Replacement
1. Remove the engine control unit. (Refer to page
4B-91)
2. Replace the E/L control unit.
3. Install in the reverse order of removal.
4B—93

Fuel filter Solenoid valve *1 Solenoid valve *1
(No.2 purge control) (No.1 purge control)
Separator Three way
Injector
,Distributor
Fuel pump
In-take filter
Air flow sensor
Water thermo sensor
Knock sensor
switches
Intake air thermo sensor
— Water thermo switch *1 __ j—Ig. switch (ST) j_J,—lg. switch (ON) -A/C switch 'A/C magnet clutch P/S switch —Head light switch —Rear defroster switch —Cooling fun switch —Blower switch —Neutral and clutch
O) <
{/> H m
g >
o 3D >
^Throttle sensor *1
Air valve
Solenoid valve
(ISC)
EGR control valve *1
EGR modulator valve *1
0 1 CO
a *1...Unleaded fuel only
*2...Leaded fuel only
Oxygen
sensor *1
One-way check valve
Shutter valve actuator Catalytic
converter *1 Solenoid valve (VIC)
O c
m
o