coolant temperature MAZDA 626 1987 Owner's Guide

PRC SYSTEM 4C
COMPONENT DESCRIPTION
Component Function Remark
Engine control unit Detects signals from input sensors and switches; con-trols solenoid valve (Pressure regulator control)
Ignition switch
(ST position)
Sends engine cranking signal to engine control unit
Intake air thermo sensor Detects intake air temperature; sends signal to engine control unit
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Pressure regulator Adjusts fuel pressure supplied to injectors
Solenoid valve (Pres-
sure regulator control)
Controls vacuum to pressure regulator Cuts vacuum when hot
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Idle switch Detects when throttle valve closed; sends signal to engine control unit ON at idle
76G04C-129
TROUBLESHOOTING
Check the condition of the wiring harness and connections before checking the sensors or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to pages 4C—10 and 11.)
Possible
\ cause
\ Page
Solenoid valve (Pres-sure regula-tor control)
Water thermo
sensor
Intake air
thermo
sensor
Engine con-trol unit terminal
System inspection Solenoid valve (Pres-sure regula-tor control) 2K
Symplon 4C—70 4C—107 4C-110 4C—98 4C—70
Engine stalls or runs rough after hot starting 2 3 4 5 1
76G04C-130
4C-69

DECELERATION CONTROL SYSTEM 4C
COMPONENT DESCRIPTION
Component Function Remarks
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 ON at idle
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
76G04C-135
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensor or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to page 4C—10 and 11.)
Possible cause Water thermo sensor System inspection
Page 4C—107 4C—74
Checking order 2 1
76G04C-136
4C-73

EGR SYSTEM (UNLEADED FUEL) 4C
EXHAUST GAS RECIRCULATION
(EGR)
SYSTEM (UNLEADED FUEL)
This system introduces exhaust gas into the intake manifold to reduce NOx emissions. It operates de-
pending on the engine load, engine speed (1,500—3,500 rpm), engine coolant temperature (above
70°C, 158°F), and radiator coolant temperature (above 17°C, 63°F).
COMPONENT DESCRIPTION
Component Function Remark
EGR control valve Recirculates portion of exhaust gas
EGR modulator valve Controls vacuum acting on EGR control valve
Engine control unit Detects signals from input sensors and switches; con-trols solenoid valve (EGR)
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit
Solenoid valve (EGR) Controls vacuum to EGR control valve
Throttle sensor Detects throttle valve opening angle; sends signal to en-
gine control unit
Installed on throttle body
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)
76G04C-143
AC—17

4C EEC SYSTEM
EVAPORATIVE EMISSION CONTROL
(EEC)
SYSTEM
Water thermo sensor
76G04C-150
Unleaded fuel:
This system stores fuel vapor generated in the fuel tank in the canister when the engine is not running.
The fuel vapor is stored in the canister until it is drawn into the dynamic chamber and burned when
the engine is started.
Leaded fuel:
Fuel vapor generated in the fuel tank flows out to the atmosphere.
COMPONENT DESCRIPTION
Application
Component Function Remark New
model Prevtoui model
Air flow sensor Detects amount of intake air; sends signal to engine control unit
O X
Charcoal canister Stores fuel tank fumes while engine stopped
o X
Engine control unit Detects signals from input sensors and
switches; controls solenoid valves (Purge
control)
o X
Ne signal pick-up Detect crank angle at 180° intervals; sends signal to engine control unit
Installed in distributor o X
Separator Prevents fuel from flowing into charcoal canister
o o
Solenoid valve
(No.1 purge control)
Controls vacuum to solenoid valve (No.2
purge control) and vacuum switch valve
0 X
Solenoid valve (No.2 Purge control)
Controls vacuum to vacuum switch valve o X
Three-way check valve Controls pressure in fuel tank o X
Two-way check valve Controls pressure in fuel tank X o
Vacuum switch valve Regulates evaporative fumes from canis-ter to intake manifold
o X
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
0 X
76G04C-151
4C-80

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

TROUBLESHOOTING (G4A-HL) 7B
STEP 3 (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
83U07B-038
7B—49