MAZDA 626 1987 Workshop Manual

4C EXHAUST SYSTEM (LEADED FUEL)
REMOVAL AND INSTALLATION
1. Remove in the sequence shown in the figure.
2. Install in the reverse order of removal.
Torque Specifications
1. Main silencer
2. Middle pipe
3. No. 2 pre-silencer
76G04C-165
4. No. 1 pre-silencer
5. Bracket
6. Front pipe
4C—90

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

CONTROL SYSTEM 4C
Output Devices and In put Devices (Leaded fuel)
IGNITION SWITCH
(ON POSITION) X X X X X O X X X X O
TEST CONNECTOR X X X O X X X X X O X
KNOCK SENSOR 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
P/S PRESSURE SWITCH X X X o X X X X X X X
A/C SWITCH X X X o X X X X O X X
IGNITION SWITCH (STA POSITION) O O X o O X O X X O X
NEUTRAL AND
CLUTCH SWITCH O X X o X X X X X X X
INTAKE AIR THERMO SENSOR X X X X X X O X X X X
WATER THERMO SENSOR O X X o X X O X X O o
IDLE SWITCH o X X o X X o X X O X
VARIABLE RESISTOR (IN AIR FLOW SENSOR) o X X X X X X X X X X
AIR FLOW SENSOR o X X X X X X X X O O
Ne SIGNAL o o X O o X O o X o O
G SIGNAL X O 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

(PRESSURE

REGULATOR

CONTROL)

SOLENOID

VALVE

(VARIABLE

INERTIA

CONTROL)

A/C
RELAY

IGNITER
AIR

FLOW

SENSOR

(BURN-OFF)

INPUT

DEVICE

OUTPUT

DEVICE

INJECTOR
BAC

VALVE

CONTROL
RELAY
SOLENOID

VALVE

(PRESSURE

REGULATOR

CONTROL)

SOLENOID

VALVE

(VARIABLE

INERTIA

CONTROL)

A/C
RELAY

IGNITER
AIR

FLOW

SENSOR

(BURN-OFF)

76G04C-168
4C—93

4C CONTROL SYSTEM
Output Devices
and
Engine Conditions (Unleaded fuel)

REMARK

*
Above

7,000

rpm:

fuel

cut

'Coolant

temp.:
below

50°C

(122°F)

41 Coolant
temp:

below

70°C

(158°F)

*2 Engine
speed
above
1,700
rpm
*3 Engine

speed:

1,500—3,500

rpm

*
During
hot

start

only

*
Engine
speed:
above

5,200

rpm

'Engine

speed:
above

3,000

rpm

'Delays

0.5
second

IGN:

ON

(ENGINE
NOT RUNNING)

No

injection

No bypass OFF
(main

fuel

pump

not
operated)
OFF
OFF
z
1

IDLE

(THROTTLE
VALVE
FULLY CLOSED)
Rich

and

i
lean
Sequential
(once

per

two

revolutions)
OFF

o en C3 UJ
z
"After

start-
ing:

ON

(Vacuum

cut) OFF
o

DECELE-
RATION
'Fuel

cut

L

Small
amount
of
bypass
air
N (1st
stage
operate:

o
o Ho 3 O CO CD > CO >
>; CO
CO c o
c o o

HEAVY
LOAD
•ST c
Closed

Small
amount
of
bypass
air

-co-CD CO
N (1st
stage
operate:

In CD 2? 03 a. o CD o> CO to "O c

*3 OFF (EGR)

o Ho 3 O CO CD > CO >
03 k-o CO c 03 CO z o *
CD c O) c 03 c o
c o o a 3

ACCELE-
RATION
Rich

o •*—• 3 o > CD
O

Small
amount
of
bypass
air

03 Q. O Q. E 3

ON

O
In CD 2? 03 a. o CD o> CO to "O c
ON
(EGR cut)
:F (Vacuum
to
pressure

regulatt

03 3 -C CO o
c 03 CS3 > X o o
z o * CO •o c CD Q. CD T3
C CO CD o "O 3= O c: 3 CO
LL LL o

MEDIUM
LOAD
WARM
Rich

and lean

|
Q. CD O
CD D
C CO E
CVJ.
z o fS *
*3 OFF (EGR)
:F (Vacuum
to
pressure

regulatt

E 3 3
c 03 i t 3 G, LL LL
T3 CD O c CO > "O <
C CO CD o "O 3= O c: 3 CO
LL LL o

MEDIUM
LOAD

COLD

ro
c CD 3 cr
z O "a CD a? CD CL o

F (2nd
stage
not
operated)
:F (Vacuum
to
pressure

regulatt

z o * O «

WARMING
UP

(DURING
IDLE)
Rich

CD CO c CD Q-O
o
c 3 CO O CO E CO
o c F (2nd
stage
not
operated)

tr O UJ
z o
O
LL z
Fixed

at

BTDC

12°

CRANKING
(COLD
ENGINE)
1
group
(twice

per

revolution)

CO
«
CD urn i CO
CO
LL LL O
LL O * « o o
LL LL o
Fixed
at

BTDC

6°

z o

SOLENOID
VALVE
(PRESSURE
REGU-

LATOR

CONTROL)

CC
o z o o iii z
o z 111

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
REGU-

LATOR

CONTROL)
SOLENOID
VALVE
(VARIABLE
INE
TIA
CONTROL)

> <
Ul oc oc o
£T u. O 1 z oc 3 m
oc o

OUTPUT
DEVICE
INJECTOR
BAC
VALVE
CONTROL
RELAY
SOLENOID
VALVE
(No.1
PURGE)
SOLENOID

VALVE

(NO.2

PURGE)
SOLENOID
VALVE
(EGR)
SOLENOID
VALVE
(PRESSURE
REGU-

LATOR

CONTROL)
SOLENOID
VALVE
(VARIABLE
INE
TIA
CONTROL)

tn z Ul (0 z Ul o >-X o
A/C

RELAY

IGNITER

z Ul (O
=5 o
IL oc <
76G04C-169
4C—94

CONTROL SYSTEM
4C

Output Devices
and
Engine Conditions (Leaded fuel)

REMARK

E Q
O O O r-»" CD > o n <

fuel
cut

'Coolant

temp.:

below

50°

(122°F)

*
During

hot
starting
only

*
Engine

speed:

above

5,400

rpm

'Delays

0.5

seconds

IGN:
ON
(ENGINE
I
NOT
RUNNING)

o
z
injection
No
bypass
OFF

(main

fuel

pump

not
operated)
OFF
LL
I

IDLE
(THROTTLE
VALVE
FULLY
CLOSED)
Rich

I
Sequential (once
per
two

revolutions)
"After

start-
ing:
ON

(vacuum

cut)
O

DECELE-
RATION

i

i
'Fuel

cut

•o CD CO "co" CD ts o to 3 o CO CD > CO
CO c o
c o o

HEAVY
LOAD
sz "co" c
O o CO CO CO Q. >. -O
O
CD Q. O CL E CL ® D
C CO F
o 08 3 u> £ CD 3 CO 0) CD
o to 3 o CO CD > CO
z

c o o c
B

ACCELE-RATION

ir o 3 0 > CD 1 O
C
O E CO
"CO
CD Q. O CL E CL ® D
C CO F
z

o 08 3 u> £ CD 3 CO 0) CD
CD e 3 SZ CO o
O * CO
c CD CL CD T3
c CO 8 "D

'
MEDIUM
LOAD
WARM
Normal

CD Q. CD O
E CO
z
O
o o_ O
E
3 3
o CO ^ LL LL O
E 3 3 O CO
•o "O <
c
3
m
LL LL o

'
MEDIUM
LOAD
COLD

.H C CD 3 CT
o_ O
E
3 3
o CO ^ LL LL O

z
o *

WARMING
UP

(DURING
IDLE)
Rich

CD CO

*Open

B
3
CO
O
CO
E
<®
LL
Fixed

at
BTDC
12°

CRANKING
(COLD
ENGINE)
1
group
(twice

per

revolution)

CO
«
0)
>,
u>n w-CO
o

OFF
Fixed

at

BTDC

6°
ENGINE
CONDITION
OUTPUT
DEVICE
FUEL
INJECTION

AMOUNT
'
FUEL
INJECTION

TIMING
AIR

VALVE
ISC
VALVE
FUEL
PUMP
CONTROL MAIN
POWER
CONTROL
SOLENOID
VALVE
(PRESSURE
REGU-

LATOR

CONTROL)
SOLENOID
VALVE
(VARIABLE
INER-
TIA
CONTROL)

(T ik 0 1 z DC 3
ffl

OC o tn

OUTPUT
DEVICE
INJECTOR
BAC
VALVE
CONTROL
RELAY
SOLENOID
VALVE
(PRESSURE
REGU-

LATOR

CONTROL)
SOLENOID
VALVE
(VARIABLE
INER-
TIA
CONTROL)

A/C

RELAY

IGNITER

Z Ul tn
£ o
ik DC <
76G04C-170
4C—95

4C CONTROL SYSTEM
EGI MAIN FUSE
Inspection
Check the continuity of EGI main fuse.
69G04A-161
CONTROL RELAY
Power Supply Circuit
1. Check that a "clicking" sound is heard at the con-
trol relay when turning the ignition switch ON and
OFF.
Note
The control relay is located under the center
console.
76G04C-171
2. Apply 12V to the 2B terminal and ground the 2D
terminal of the control relay.
3. Check voltage at the terminals with an voltmeter.
terminal
Terminals Grounded Not grounded
2C 12V OV
2E 12V OV
76G04C-172
From EGI From '9' From Ig. main fuse switch (ON) / switch
(ST)
To C/U / 9round To main To injector fuel Pump
Fuel Pump Circuit
1. Apply 12V and a ground to the terminals described
below and check the terminals with an ohmmeter
or voltmeter.
Terminal applied 12V
Terminal
grounded
Terminal checked
Correct condition
1B 1D 2F-1A Continuity
2F 1C 1A ADDrox.12V
76G04C-173
4C-96

CONTROL SYSTEM 4C
Resistance
Check resistance between the terminals with an
ohmmeter.
Between terminals Resistance (Q)
1B « 1D More than approx. 20
2F <- 1C More than approx. 60
2F « 1A oo
2B « 2D More than approx. 60
2B ~ 2C oo
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. Reconnect 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. Reconnect the switch connector.
Note
Refer to Section 6 for replacement of the
clutch switch.
P/S PRESSURE SWITCH
Inspection
1. Disconnect the P/S pressure switch connector.
2. Connect an ohmmeter to the switch.
3. Start the engine. Check continuity of the switch
while turning the steering wheel at idle.
P/S Continuity
Turning Yes
Not turning No
4. Reconnect the switch connector.
Note
Refer to Section 10 for replacement of the P/S
pressure switch.
4C-97

4C CONTROL SYSTEM
ENGINE CONTROL UNIT
Engine Signal Monitor (49 9200 162) and Adapter (49 9200 163).
Adapter harness 49 9200 163
Engine wiring harness^
Selector switch
' —
Monitor switch
49 9200 162
Control unit terminal number
Terminals (A and B)
Q IIIM«I
76G04C-178
The Engine Signal Monitor (49 9200 162) is used to check the control unit terminal voltages.
How to Use the Engine Signal Monitor
1. Connect the Engine Signal Monitor (49 9200 162) between the engine control unit and the en-
gine harness using the adapter (49 9200 163).
2. Turn the selector switch and monitor switch to select the terminal number.
3. Check the terminal voltage.
Caution
Never apply voltage to terminals A and B.
4C—98

CONTROL SYSTEM 4C
Terminal Voltage
If the input and output devices wiring are normal, but the engine control unit terminal voltage is incor-
rect, replace the engine control unit.
Terminal Input Output Connection to Voltage (After warming-up) Remark Terminal Input Output Connection to Ign: ON Idle Remark
1A — — — — — —
1B o Self-Diagnosis Checker (Code No.)
For 3sec. after ignition switch OFF ->• ON: below 2.5V (Buzzer sounds) After 3sec.: approx. 12V (Buzzer does not sound)
• Using Self-Diagnosis Check-er and test con-nector grounded • Buzzer sounds: below 2.5V • Buzzer does not sound: approx. 12V
1C o
Solenoid valve (Variable inertia control) Approx. 12V
Above 5200 rpm (Unleaded fuel) or 5400 rpm (Leaded fuel): Below 2.5V
1D o Self-Diagnosis Checker (Monitor lamp)
For 3sec.after igni-tion switch OFF -» ON:
approx. 5V (light il-luminates)
After 3sec.: approx. 12V (light does not illuminate)
(Test connector grounded) approx. 5V (Test connector not grounded) Monitor lamp ON: approx. 5V Monitor lamp OFF: approx. 12V
With Self-Diagnosis
Checker
1E O Idle switch Accelerator pedal released: OV
Accelerator pedal depressed: approx. 12V
1F o A/C relay A/C switch ON: below 2.5V
A/C switch OFF: approx. 12V Blower motor ON
1G O Neutral or clutch switch
In-gear condition Clutch pedal depressed: approx. 12V Clutch pedal released: OV
MTX (Neutral: con-stant approx. 12V)
1H
(U/F) o Water thermo
switch
Approx. 12V Radiator temp.: be-low 17°C (63°R 1H
(U/F) o Water thermo
switch OV Radiator temp.:
above 17°C (63°F)
11 o Electrical load control unit E/L switch ON: below 2.5V
E/L switch OFF: approx. 10—12V
Electrical load: Rear defroster switch
Headlight switch Blower motor switch (3rd & 4th position) Electrical fan switch
1J — — — — —
1K o P/S pressure
switch
Constant approx.
12V
P/S ON: below 2.5V P/S OFF: approx. 12V
1L o A/C switch A/C switch ON: below 2.5V A/C switch OFF: aDDrox. 12V Blower motor: ON
1M o Distributor
(Ne signal) OV or 5V Approx. 2.0V
1N o Distributor (G signal) OV or 5V Approx. 1.2V
Note
Terminals labeled "U/F" are only for unleaded fuel.
4C-99