Component Descriptions - Mazda MX-5 1990 Workshop Manual

I. _
F
OUTLINE
COMPONENT DESCRIPTIONS
Component
Function Remark
Air cleaner
Filters air entering throttle body
Airflow meter Detects amount of intake air; sends signal to
-Intake air thermosensor and fuel pump
engine control unit switch included
• Use Vref (5 volt) as power source
Air valve When cold, supplies bypass air into dynamic
• Engine speed increased to shorten warm-up
chamber period
- Thermowax type
Atmospheric pressure
Detects atmospheric pressure; sends signal to Built-in ECU
sensor
engine control unit
Catalytic converter Reduces HC, CO, and NOx by chemical Monolith type
reaction
Charcoal canister Stores gas tank fumes while engine stopped
Circuit opening relay Voltage for fuel pump while engine running
Clutch switch (MIT)
Detects in-gear condition; sends signal to Switch OFF when clutch pedal released
engine control unit
Diagnosis connector
Concentrated service connector 21-pin (Black)
Concentrated terminals are:
1. EGI self-diagnosis terminal
2. Initial set terminal
3. Fuel pump check terminal
4. Cooling fan check terminal
Crank angle sensor
G-signal Detects No.1 cylinder TDC; sends signal to
engine control unit
Ne-signal Detects crank angle at 180 0 intervals; sends
signal to control unit
Dynamic chamber Interconnects all cylinders
Engine control unit Detects the following:
(ECU)
1. AIC
operation 1.
AIC
switch
2. Airlfuel ratio (Oxygen concentration) 2. Oxygen sensor
3. Atmospheric pressure 3.
Atmospheric pressure sensor
4. Braking signal 4. Stoplight switch
5. Cranking signal
5. Ignition switch (START position)
6. ElL operation 6. Cooling fan relay
Light and turn relay
Blower motor switch
7. Engine coolant temperature 7. Water thermosensor
8. Engine speed
8. Crank angle sensor (Ne-signal)
9. In-gear condition 9. Neutral and clutch switches
10. Intake air amount 10. Airflow meter
11 . Intake air temperature 11. Intake air thermosensor
12. No.1 piston TDC 12. Crank angle sensor (G-signal)
13. PIS operation 13. PIS pressure switch
14. Initial set signal 14. Diagnosis connector
15. Throttle valve fully closed 15. Throttle sensor (IDL signal)
16. Throttle valve opening amount 16. Throttle sensor (POW signal)
Controls operation of the following:
1. AIC
(Cut off) 1.
AIC
relay
2. Fail-safe function
2. Self-diagnosis checker and MIL
3. Fuel injection system 3. Injector
4. Idle speed control
4. ISC valve
5. Ignition timing control system
5. Igniter
6. Monitor function
6. Monitor lamp (Self-diagnosis checker)
7. Purge control system 7. Solenoid valve (Purge control)
F-10