MAZDA 626 1987 Workshop Manual

CONTROL SYSTEM 4B
Terminal Input Output Connection to Voltage (After warming-up) Remarks Terminal Input Output Connection to IGN: ON Idle Remarks
1P — — — — —
1Q — — — — —
1R — — — — —
1S o Air bypass solenoid valve (Idle-up C) and P/S pressure switch
Battery voltage While solenoid ON (Refer to page 4B—35): below 1.5V
1T — — — — —
1U — — — — —
1V 0 MTX
Neutral and clutch switch
In-gear condition Clutch pedal depressed: battery voltage Clutch pedal released: below 1,5V
Neutral: constant battery voltage
1W O Test connector Test connector grounded: below 1,5V Test connector not grounded: battery voltage Green connector, 1-pin
1X — — — — —
2A o V ref 4.5—5.5V
2B 0 Air flow meter (Vc) 6-10V
2C — — Ground (E2) Approx. OV
2D o Oxygen sensor OV 0-1.OV • Cold engine: 0V at idle • After warming-up: Increase engine speed: 0.5—1.0V Deceleration: 0—0.4V
2E 0 Air flow meter (Vs) Approx. 1.7V Approx. 3—5V Increase engine speed:
voltage increases
2F — -— — —
2G 0 Throttle sensor Accelerator pedal released:
0.4—0.6 V
2H 0 Atmospheric pres-sure sensor At sea level: approx. 4.0V
21 0 Water thermo sensor 0.3—0.6 V Engine coolant temp. 20°C (68°F): approx. 2.5V
2J o Air flow meter (In-
take air thermo
sensor)
Approx. 2.3V at 20°C (68°F)
2K o Solenoid valve (Pres-
sure regulator
control)
For 120 sec. after ignition switch OFF - ON: below 1.5V
For 120 sec. after
starting: below 1.5V
Hot condition: Cool-ant temp, above 70°C (158°F) Intake air temp, above 10°C (50°F)
2K o Solenoid valve (Pres-
sure regulator
control)
Battery voltage Other conditions
2L — — — — —
2M — — —
4B-89

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
P/S pressure switch-^—^
86U04A-176
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. Connect the switch connector after checking.
Note
Refer to section 10 for replacement of the P/S
pressure switch.
INHIBITOR SWITCH
Inspection
1. Disconnect the inhibitor switch connector.
2. Connect an ohmmeter to the switch.
3. Check continuity of the switch.
Position Continuity
P and N ranges Yes
Other ranges No
4. Connect the switch connector after checking.
Note
Refer to Section 7B for replacement of the in-
hibitor switch.
4B—92

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

4B CONTROL SYSTEM
AIR FLOW METER
Potentiometer
Intake air thermo
sensor Fc EI E2 VB VC VS THA
Fuel pump switch
Connector-—
I
lOQDOQOD i
69G04C-100
Inspection
1. Remove the air flow meter. (Refer to page 4B—31)
2. Check the air flow meter body for cracks.
3. Verify that the measuring plate moves smoothly.
4. Disconnect the connector from the air flow meter.
5. Using an ohmmeter, check resistance between the
terminals with the measuring plate fully closed and
fully open.
6. Connect the connector to the air flow meter after
inspecting.
76G04B-112
Terminal Resistance (Q) Terminal Fully closed | Fully open
E2<->VS More than 20
E2«VC 100-300
E2«VB 200-400
E2«THA (Intake air thermo sensor)
-20°C (—4°F) 13.6-18.4 kfi 20°C (68°F) 2.21-2.69 kfi 60°C (140°F) 493—667 0
Ei<->Fc OO 0
Note
Refer to page 4B—31 for replacement of the
air flow meter.
76G04B-113
4B—94

CONTROL SYSTEM 4B
76G04B-114
c jr y—

D
'
CO CO

76G04B-115
76U04A-018
THROTTLE SENSOR
Inspection of Terminal Voltage
1. Remove the rubber boot from the connector.
2. Turn the ignition switch ON.
3. Check voltage between each terminal and a
ground.
4. Open the throttle valve and again check voltage
between each terminal and a ground.
Condition
Terminal Closed Fully open
A(Vt) 0.4—0.6V Approx. 4.0V
B (GND) Below 1.5 V
C (V ref) 4.5—5.5 V
D (IDL) Below 1.5 V Approx. 12 V
5. If not correct at the D terminal only, check the throt-
tle sensor setting.
6. If not correct on other terminals, check resistance
at the throttle sensor (Refer to page 4B—97) and
terminals (2A, 2C, 1E and 2G) (Refer to page
4B—88 and 89) of the engine control unit and wir-
ing harness.
7. Install the rubber boot on the connector.
Throttle Sensor Setting
Inspection
1. Disconnect the connector from the throttle sensor.
2. Connect the SST to the throttle sensor or connect
an ohmmeter between terminals B and D.
76G04B-116
4B-95

4B CONTROL SYSTEM
y
/OTaWX 1
rx
Throttle stop screw
76G04B-117
76G04B-11E
Counter clockwise i i
Clockwise
76G04B-119
3. Place a feeler gauge between the lever and the
throttle stop screw and check that the SST buzz-
er sounds or that there is continuity between ter-
minals B and D.
Feeler gauge 0 mm (0 in) 0.7 mm (0.028 in)
Buzzer Sounds Does not sound
Lamp ON OFF
Continuity YES NO
4. If not correct, adjust the throttle sensor as outlined
below.
Adjustment
1. Disconnect the connector and connect the SST
to the throttle sensor.
2. Place a 0.40 mm (0.016 in) feeler gauge between
the lever and the throttle stop screw.
3. Loosen the two attaching screws.
4. Rotate the throttle sensor clockwise about 30°, then
rotate it counterclockwise until the buzzer sounds.
5. If it does not buzz, replace the throttle sensor.
6. If it does buzz, substitute the feeler gauge with a
0.55 mm (0.022 in) gauge
7. Check that the buzzer does not sound.
8. If it buzzes, repeat steps 3 to 7.
If it still buzzes, replace the throttle sensor.
9. Tighten the two attaching screws.
Note
Be careful not to disturb the throttle sensor
position when tightening the screws.
10. Open the throttle valve fully a few times; then
recheck the adjustment of the throttle sensor.
11. Disconnect the SST from the throttle sensor and
reconnect the connector.
76G04B-120
4B-96

4B CONTROL SYSTEM
A:
56G04B-038
j Water thermo
sensor
86U04A-202
86U04A-203
Inspection of Resistance
1. Disconnect the connector from the sensor.
2. Check resistance between the terminals as shown
in the table.
3. Open the throttle valve fully and check resistances
between terminals.
Terminal Closed Fully open
A « B Approx. 500 Q Approx. 4.5 kQ
B «- C 4-6 kQ
4.If not correct, replace the throttle sensor.
WATER THERMO SENSOR
Inspection
1. Remove the water thermo sensor from the cylin-
der head.
2. Place the sensor in water with a thermometer and
heat the water gradually.
3. Check resistance of the sensor with an ohmmeter.
Coolant Resistance
-20°C ( -4°F) 14.5-17.8 kQ
20°C ( 68°F) 2.2-2.7 kfi
40°C (104°R 1.0—1.3 kfi
60°C (140°F) 500—640 n
80°C (176°F) 280-350 Q
4. If not correct, replace the water thermo sensor.
WATER THERMO SWITCH
Inspection
1. Remove the switch from the radiator.
2. Place the switch in water with a thermometer, and
heat the water gradually.
3. Check for continuity of the switch with an
ohmmeter.
Coolant temp. Continuity
More than approx. 17°C (63°F) Yes
Less than approx. 17°C (63°F) No
76G04B-132 4. If not correct, replace the water thermo switch.
4B—97

4B CONTROL SYSTEM
76G04B-121
86U04A-206
Check connector; Green (6 pin)y
49 H018 9A1
OXYGEN SENSOR
Inspection of Output Voltage
1. Warm up the engine and run it at idle.
2. Disconnect the oxygen sensor connector.
3. Connect a voltmeter between the oxygen sensor
and ground.
4. Run the engine at 4,000 rpm until the voltmeter
indicates approx. 0.55V.
5. Increase and decrease the engine speed suddenly
several times. Check to see that when the speed
is increased the meter reads between 0.5V—1.0V,
and when the speed is decreased it reads between
0V—0.4V
6. If the voltmeter doesn't indicate as specified, re-
place the oxygen sensor.
Inspection of Sensitivity
Caution
Do not ground the test connector (Green,
1-pin).
1. Warm up the engine to the normal operating tem-
perature and run it at idle.
2. Connect the SST to the check connector.
76G04B-133
Monitor lamp
SELF-DIAGNOSIS CHECKER
MONITOR > o .000 /TT\' o
SELECT SW «
86U04A-208
3. Increase the engine speed to between 2,000 and
3,000 rpm, and check that the monitor lamp flash-
es for 10 seconds.
Monitor lamp: Flashes ON and OFF
more than 8 times/10 sec
4B—98