1987 MAZDA 626 coolant

4C CONTROL SYSTEM
E/L CONTROL UNIT
Inspection
1. Connect a voltmeter between the E/L control unit
and a ground.
2. Start the engine and check the terminal voltages
as described below.
76G04C-180
Terminal Input Output Connection to Voltage (after warm-up) Remarks Terminal Input Output Connection to Ignition switch: ON Idle Remarks
A
(BW) — — Ignition switch Approx. 12V
B — — — — — —
C
(B) — — Ground OV
D (LY) O Electrical fan relay Approx. 12V Coolant temp.: below 97°C (207°F) D (LY) O Electrical fan relay
Below 1,5V Coolant temp.:
above 97°C (207°F)
E (GY) Control unit (11) OV E/L: ON E (GY) Control unit (11)
Approx. 12V E/L: OFF
F (W) O Headlight switch Approx. 12V Headlight switch:
ON F (W) O Headlight switch
Below 1,5V Headlight switch:
OFF
G (LB) o Blower motor switch Below 1.5V Blower motor switch: ON (3rd or 4th position) G (LB) o Blower motor switch
Approx. 5V Others
H
(BL) o Rear defroster
switch
Below 1.5 V Rear defroster
switch: ON H
(BL) o Rear defroster
switch Approx. 12V Rear defroster switch: OFF
76G04C-181
Replacement
1. Replace the E/L control unit.
2. Install in the reverse order of removal.
76G04C-182
4C—102

4C CONTROL SYSTEM
4. Make sure that the throttle valve is fully closed.
5. Turn the throttle sensor so that the BLUE wire volt-
age indicates within the specified closed range.
6. Tighten the throttle sensor mounting screw.
7. Recheck that the BLUE wire voltage is within the
specified range.
76G04C-195
8. Turn the ignition switch OFF.
9. Disconnect the SST and reconnect the throttle sen-
sor connector.
10. Disconnect the negative battery terminal and de-
press the brake pedal for 5 seconds to eliminate
the from the malfunction memory from the control
unit.
76G04C-196
76G04C-198
4C-106
IDLE SWITCH
Inspection
1. Disconnect the idle switch connector.
2. Check continuity between the switch and a ground.
Throttle valve condition Continuity
Fully closed Yes
Open No
3. If not correct, check condition of the wiring harness
of the idle switch. Replace the idle switch and throt-
tle body as an assembly, if necessary.
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. 10°C (63°F) No
4. If not correct, replace the water thermo switch.

CONTROL SYSTEM 4C
WATER THERMO SENSOR
Inspection
1. Remove the water thermo sensor.
76G04C-199
86U04A-203
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 kfl
20°C ( 68°F) 2.2-2.7 kQ
40°C (104°F) 1.0—1.3 kQ
60°C (140°F) 500—640 O
80°C (176°F) 280—350 fl
4. If not correct, replace the water thermo sensor.
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 a ground.
4. Run the engine at 4,500 rpm until the voltmeter
indicates approx. 0.7V.
76G04C-200
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 .OV,
and when the speed is decreased it reads between
OV—0.4V.
6. If the voltmeter dosen't indicate as specified, re-
place the oxygen sensor.
86U04A-206
4C—107

QUICK START SYSTEM (QSS) 5
SYSTEM OPERATION
The Quick Start System has three functions: Pre-heating, Chopping, and After-glow; as used in
the previous model. Each function operates as follows:
1. Pre-heating After ignition switch is turned to ON position, current flows to glow plug for 6
sec.
2. Chopping While engine switch is in START position, current flows to glow plug con-
tinuously.
3. After-glow (coolant temperature below 30°C (86°F):
a) When engine switch is kept in ON position after pre-heating, current flows to
glow plug continuously for 15 sec.
b) After engine has stared, current flows to glow plug continuously for 15 sec.
Indicator lamp: Indicator illuminates for 3 sec. after ignition is ON position.
When ignition switch is ON-START-ON position
When ignition switch is kept in ON position
76G05X-050
5-77

QUICK START SYSTEM (QSS) 5
CONTROL UNIT
Inspection
1. Connect a voltmeter to the control unit as shown
in the figure.
2. Check the voltage of the terminal.
3. Replace the control unit if necessary.
Caution
If the proper voltage is not indicated on the
voltmeter, check all wiring connections and
finally, check that component.
63G05X-337
Control Unit Connector
Terminal Input Output Connection to Operation condition Voltage Remark
for 6 sec. approx. 12V
L (GW) O Glow plug relay Engine switch: ON (No cranking) after 6 sec.
OV 12V Coolant temperature; below 30°C (86°F) after 6 sec.
OV Coolant temperature; above 30°C (86°F)
H
(B) — — Ground OV
E (BW) 0 Engine switch (ON) Engine switch: ON approx. 12V
F
(BR) O Engine switch (START) Engine switch: START approx. 12V
C o
Water
temperature switch
Engine switch: ON (No cranking)
approx. 12V Coolant temperature; below 30°C (86°F)
(BrB) o
Water
temperature switch
Engine switch: ON (No cranking)
approx. OV Coolant temperature;
above 30°C (86°F)
At cranking OV <- 12V
B 0 Glow plug
For 15 sec. after engine has started OV <-> 12V Coolant temperature;
(Gr) 0 Glow plug After 15 sec. OV below 30°C (86 °F)
After engine has started OV Coolant temperature; above 30°C (86°F)
K o Indicator Engine switch: ON
For 3 sec. OV
(WR) o Indicator Engine switch: ON after 3 sec. approx. 12V
76G05X-052
u® x y i © © X 1
© © X ®
5-79

TROUBLESHOOTING (G4A-EL) 7B
Item Indication Condition Possible cause
BRAKE LIGHT SW ON Brake pedal depressed Brake light switch or
wiring BRAKE LIGHT SW
OFF Brake pedal released
Brake light switch or
wiring
WATER TEMP SW ON Coolant temperature 72°C (162°F) or above Water temp switch or wiring WATER TEMP SW
OFF Coolant temperature lower than 65°C (149°F)
Water temp switch or wiring
ATF TEMP SW ON ATF temperature 150°C (302°F) or above Fluid temperature switch or wiring ATF TEMP SW
OFF ATF temperature lower than 143°C (289°F)
Fluid temperature switch or wiring
CRUISE CONTROL SW Not used — —
Input (Digital display)
THROTTLE SENSOR
EC-AT control unit terminal voltage All the time Throttle sensor, idle switch or wirings
VEHICLE SPEED*
Vehicle speed calculated from speed sensor signal
All the time Vehicle speed sensor, speedometer cable, or wiring
DRUM SPEED* Drum speed All the time Pulse generator or wirings
Output (Light)
1-2 SOLENOID VALVE*
ON
Refer to page 7B—26 solenoid valve operation table
Control unit, 1-2 shift sol., or wiring 1-2 SOLENOID VALVE* OFF
Refer to page 7B—26 solenoid valve operation table
Control unit, 1-2 shift sol., or wiring
2-3 SOLENOID VALVE*
ON Refer to page 7B—26 solenoid valve operation table Control unit, 2-3 shift sol., or wiring 2-3 SOLENOID VALVE* OFF
Refer to page 7B—26 solenoid valve operation table Control unit, 2-3 shift sol., or wiring
3-4 SOLENOID VALVE*
ON
Refer to page 7B—26 solenoid valve operation table
Control unit, 3-4 shift sol., or wiring 3-4 SOLENOID VALVE* OFF
Refer to page 7B—26 solenoid valve operation table
Control unit, 3-4 shift sol., or wiring
LOCK-UP SOLE-NOID VALVE*
ON Lock-up condition Control unit, lock-up sol., or wiring LOCK-UP SOLE-NOID VALVE* OFF Non-lock-up condition
Control unit, lock-up sol., or wiring
HOLD INDICATOR ON Hold mode Control unit, Hold switch, or wiring HOLD INDICATOR OFF Other modes
Control unit, Hold switch, or wiring
MODE INDICATOR ON Power or economy mode Control unit, hold switch, mode switch, or wiring MODE INDICATOR
OFF Hold mode
Control unit, hold switch, mode switch, or wiring
NO LOAD SIGNAL Not used — —
76G07B-028
7B-25

TROUBLESHOOTING (G4A-EL) 7B
STEP 4 (STALL TEST)
This step is performed to determine if there is slippage of the friction elements or malfunction of the
hydraulic components.
Preparation
Check the following items prior to testing:
1. Engine coolant, engine oil and ATF levels.
2. Warm the engine thoroughly to raise the ATF temperature to operating level (50—80°C, 122—176°F).
3. Engage the parking brake and use wheel chocks at the front and rear wheels.
Pull the parking brake Water temperature
ATF
79G07C-084
7B-27

7B TROUBLESHOOTING (G4A-EL)
STEP 7 (ROAD TEST)
This step is performed to inspect for problems at the various ranges. If these tests show any problems,
adjust or replace by referring to the electronic system component or mechanical sections.
Caution
Perform the test at normal ATF operating temperature (50—80°C, 122—176°F).
D Range Test
Shift point, shift pattern, and shift shock
1. Shift the selector lever to D range and select the Power mode.
2. Accelerate the vehicle with half and full throttle valve opening.
Note
Throttle sensor voltage of the EC-AT Tester represents the throttle valve opening.
3. Check that 1-2, 2-3 and 3-OD up-shifts and downshifts and lock-up are obtained. The shift points
must be as shown in the D range (Power) shift diagram.
Note
a) Drum speed (rpm) of the EC-AT Tester represents the shift point.
b) Vehicle speed of the EC-AT Tester and speedometer and vehicle speed on a chassis
roller may not meet the specified shift pattern because of tire size. Therefore, check
the shift points with the Drum speed.
c) There is no lock-up when the coolant temperature is below 72°C (162°F).
d) There is no overdrive when the cruise control is operating and there is a 3 km/h (1.9
mph) difference between the pre-set cruise speed and vehicle speed, or set or resume
switch is ON.
e) There is no lock-up when the brake pedal is depressed.
4. Check the up-shifts for shift shock or slippage in the same manner.
5. While driving in OD, shift the selector lever to S range and check that 4-3 downshift immediately
occurs, then decelerate and check that engine braking effect is felt in only 3rd gear.
7B—34