coolant MAZDA MX-5 1994 Repair Manual

PRESSURE REGULATOR CONTROL SYSTEM PRESSURE REGULATOR CONTROL SYSTEM DATA LINK CONNECTOR - CLUTCH SWITCH (MT) (TEN TERMINAL) PARKINEUTRAL SWITCH (PCMT) (AT) THROTTLE POSITION SENSOR L 1 ,,,, INTAKE AIR TEMPERATURE 1 SENSOR (IN MASS AIRFLOW SENSOR) -;- ENGINE COOLANT TEMPERATURE SENSOR PRC SOLENOID VALVE CRANKSHAFT POSITION SENSOR PRESSURE REGULATOR PCME I Above 90°C {194OF} ( Above 70°C {158'F} I Throttle valve closed throttle position or no load condition I Approx. 150 1 I Operating condition Coolant temperature I Intake air temperature I Engine condition I I To prevent percolation of the fuel during hot restart idle, vacuum to the pressure regulator is momentarily cut, and the fuel injection pressure is increased to slightly more than 284 kPa (2.9 kgf/cm2, 41.2 psi}. Operating time (sec) Gartner Banana

F EXHAUST GAS RECIRCULATION (EGR) EXHAUST GAS RECIRCULATION (EGR) PREPARATION SST I 49 9200 162 Engine Signal Monitor 49 GO1 8 904 Sheet DESCRIPTION For inspection of EGR For inspection of EGR 49 GO1 8 903 For inspection of Adapter EGR harness / TO AIR CLEANER HOUSING I THROTTLE POSITION ENGINE COOLANT SENSOR SENSOR TEMPERATURE CRANKSHAFT SENSOR POSITION SENSOR EGR SOLENOID VALVE (VACUUM) EGR SOLENOID VALVE (VENT) / PCME I This ~~st~rn~recirculates a small amount of exhaust gas into the intake manifold to reduce the combus- tion temperature, and reduce the NOx emissions. This system consists of the EGR control valve, EGR function sensor, two solenoid valves, powertrain control module (engine) (PCME) and input devices. Gartner Banana

EXHAUST GAS RECIRCULATION (EGR) Operation Cold Engine (Coolant temperature less than 55°C (1 31 OF)) EGR operation is stopped to improve driveability when the engine temperature is cold. u Warm Engine The powertrain control module (engine) controls the solenoid valves (vacuum side and vent side) to sup- ply EGR gases as described below. Remark Operating condition Idle Deceleration High speed Heavy load EGR SOLENOID VALVE (VACUUM) I I EGR operation Acceleration Warming up Other SYSTEM OPERATION 1. Connect the SSTs to the PCME as shown. 2. Start the engine. 3. Drive the vehicle and verify that PCME terminals 1 R and 1 T voltage is battery positive voltage (B+) while the en- gine is still cold. 4. Warm up the engine to normal operating temperature and let it idle. 5. Drive the vehicle and verify that the Engine Signal Moni- tor green and red lamps flash when the SST is set to 1 R and 1 T. 6. Ground the PCME terminal IT by using a jumper wire. 7. Verify that the engine runs roughly or stalls at idle. Stopped EGR SOLENOID VALVE (VACUUM) Inspection 1. Disconnect the vacuum hoses. 2. Blow into the EGR solenoid valve (vacuum) and verify that air does not flow. 3. Disconnect the EGR solenoid valve (vacuum) connec- tor. 4. Apply battery positive voltage and a ground to the sole- noid valve as shown. 5. Blow through the EGR solenoid valve (vacuum) and verify that air flows. 6. If not as specified, replace the EGR solenoid valve (vac- uum) assembly. Idle switch: ON Above 3,125 rpm - Reduced EGR gas amount Control supply of EGR gas amount by using signal from EGR function sensor - Coolant temperature: Between 55OC (1 31 OF) and 60°C {140°F) - Gartner Banana

FUEL EVAPORATIVE SYSTEM FUEL EVAPORATIVE SYSTEM DESCRIPTION The fuel evaporative system consists of the fuel vapor valve, the two-way check valve, the charcoal can- ister, the purge solenoid valve, the powertrain control module (engine), and the input devices. The amount of evaporative fumes introduced into the engine and burned is controlled by the solenoid valve in relation to the engine's operating conditions. To maintain the best engine performance, the solenoid valve is controlled by the powertrab control module (engine). THROTTLE 1-1 POSITION SENSOR I1 I I (IDLE SWITCH) 7 BAROMETIC ABSOLUTE PRESSURE SENSOR PARWNEUTRAL SWITCH (AT) MASS AIRFLOW SENSOR CRANKSHAFT POSITION SENSOR (SGT-SIGNAL) n - DUTY - LOW HIGH (ENGINE) CHARCOAL PURGE SOLENOID VALVE CANISTER HEATED OXYGEN SENSOR ENGINE COOLANT POWERTRAIN TEMPERATURE SENSOR CONTROL MODULE CHECK VALVE # 11 FUEL VAPOR VALVE Operation The purge solenoid valve is controlled by duty signals from the powertrain control module (engine) to per- form purging of the charcoal canister. Purging is done when these conditions are met: i/ 1. After warm-up. 2. Driving in gear. 3. Accelerator pedal depressed (idle switch OFF). 4. Heated oxygen sensor functioning normally. Gartner Banana

DECHOKE CONTROL SYSTEM DECHOKE CONTROL SYSTEM DESCRIPTION To clean out excess fuel in cylinders, as in the case of engine flooding, when the engine is cold, no fuel will be injected when the accelerator is held fully depressed while cranking the engine. CRANKSHAFT POSITION SENSOR (NE-SIGNAL) n POWERTRAIN CONTROL MODULE ENGINE COOLANT TEMPERATURE SENSOR I (ENGINE) 1 DETERMINA- TION OF FUEL CUT SPEED Gartner Banana

COOLANT FAN CONTROL COOLANT FAN CONTROL OUTLINE The PCME controls the coolant fan and the condenser fan to provide more efficient fan control. This 4 improves the performance reliability and stability during idling of an engine. The coolant fan is normal when it start to operate with the data link connector TEN terminal grounded and the accerelator pedal is depressed (Ignition switch ON). IGNITION SWITCH OFF CONDENSER FAN MOTOR PCME RELAY I& MAGNETIC CLUTCH I COOLANT FAN RELAY Q COOLANT FAN MOTOR Gartner Banana

COOLANT FAN CONTROL F COOLANT FAN The coolant fan rotates at a constant velocity. 'L / Operation Condition TEN TERMINAL (DATA LINK CONNECTOR) IDLE SWITCH -----' OFF EXCEPT AT STARTING 'I ENGINE COOLANT TEMPERATURE ABOVE 97C0 (206.6F0) 1 COOLANT FAN - - ENGINE COOLANT TEMPERATURE SENSOR FAILED I A/C OPERATING CONDENSER FAN The condenser fan is operated by PCME. r The condenser fan rotates at a constant velocity. Operation Condition Except during acceralation Except at starting Other than wide open throttle Air conditioner is operating The condenser fan operates when above-mentioned conditions are satisfied. Engine coolant temperature is above 108°C (226.4OFj. TEN terminal grounded and idle switch off. Gartner Banana

COOLANT FAN CONTROL SYSTEM INSPECTION 1. Connect the SST to the data link connector. 2. Set switch @ to position 1. 3. Set the test switch to SELF-TEST. 4. Turn the ignition switch ON. 5. Rotate the throttle link by hard and verify that coolant fan and condenser fan operates. 6. Disconnect the SST. 7. If not specified, inspect as following. (Refer to page F-145.) PCME 1 N terminal voltage PCME 2H terminal voltage Coolant fan relay Condenser fan relay COOLANT FAN RELAY lnspection 1. Remove the coolant fan relay 2. Check continuity between the terminals of the relay. CONDENSER FAN RELAY 3. If not specified, replace the cooling fan relay. B+: Battery positive voltage CONDENSER FAN RELAY Inspection 1. Remove the condenser fan relay. 2. Check continuity between the terminals of the relay. i/ Terminal A - B Apply B+ B+ not applied 3. If not specified, replace the condenser fan relay. Terminal C - D Yes No B+: Battery positive voltage Terminal A - I3 Apply B+ B+ not applied Terminal C - E Yes No Gartner Banana

CONTROL SYSTEM STRUCTURAL VIEW i 1. Powertrain control module (engine) 6. Heated oxygen sensor Inspection . . . . . . . . . . . . . . . . . . page F-144 Inspection . . . . . . . . . . . . . . . . . . page F-156 Removal / Installation . . . . . . . . page F-143 Replacement . . . . . . . . . . . . . . . page F-156 2. Crankshaft position sensor 7. Main relay Removal . . . . . . . . . . . . . . . . . . . page F-153 Inspection . . . . . . . . . . . . . . . . . . page F-156 lnspection . . . . . . . . . . . . . . . . . . page F-153 8. Clutch switch Installation . . . . . . . . . . . . . . . . . page F-153 Inspection . . . . . . . . . . . . . . . . . . page F-157 3. Mass airflow sensor Replacement . . . . . . . . . . . . . . . page F-157 System inspection . . . . . . . . . . . page F-152 9. Neutral switch Inspection . . . . . . . . . . . . . . . . . . page F-152 Inspection . , . . . . . . . . . . . . . . . . page F-157 4. Engine coolant temperature sensor Replacement . . . . . . . . . . . . . . . page F-157 Removal . . . . . . . . . . . . . . . . . . . page F-154 10. Steering pressure sensor Inspection . . . . . . . . . . . . . . . . . . page F-154 Inspection . . . . . . . . . . . . . . . . . . page F-158 Installation . . . , . . . . . . . . . . . . . page F-154 Replacement . . . . . . . . . . . . . . . page F-158 5. Throttle position sensor -,' Inspection . . . . . . . . . . . . . . . . . . page F-155 Adjustment . . . . . . . . . . . . . . . . . page F-155 Replacement . . . . . . . . . . . . . . . page F-156 Gartner Banana

CONTROL SYSTEM F Terminal voltage B+: Battery positive voltage Test condition I Voltage I Remark - - - - - - - - - - - - - - - - - - Connection to Battery Constant Ignition switch OFF Main relay - B+ OV lgnition switch (Start position) For backup - Ignition switch ON While cranking Lamp illuminated for 3 sec. after 1 4.5-5.5V ianition switch OFF+ON 1 B+ Approx. 1 OV Ignition switch ON - - OV Data link connector (MEN terminal) Test switch at "SELF-TEST" .. Lamp not illuminated after 3 sec. Test switch at "02 MONITOR" at idle Monitor lam illuminated & 4.5-5.5v . . I Malfunction indicator IighVData link connector (FEN ter- minal) With Self-Diagnosis Checker and System Selector Test switch at "02 MONITOR" at idle Monitor lamp not illuminated Light illuminated and buzzer sounded for 3 sec. after ignition switch OFF-ON B+ tor tesiswitch at "SELF-TEST" With Self-Diagnosis checker and system selector Below 2.5V 1 Light illuminated and buzzer sounded 1 Below 2.5V I With System Selec- Light not illuminated and buzzer not sounded after 3 sec. I Light not illuminated and buzzer 1 n. 1 B+ not sound I D+ 1 - #I, 4 lgniter (in IG COIL) #2,3 Igniter (in IG COIL) Powertrain control module (transmis- sion) - Ignition switch ON Idle Ignition switch ON Idle lgnition switch ON (Engine coolant temp, below 60°C {I 40°F)) Ignition switch ON AtC relay Air conditioning sensor ON at idle Air conditioning sensor OFF at idle Ground (MT) - OV Approx. 0.2V OV Approx. 0.2V Below 1 .OV B+ Below 2.5V B+ - - - - , * Open (AT) - Ignition switch ON ( Below 1 .O V I Engine coolant temp. I Below .OV I ldle Above 97°C (206.6OF1 Ignition switch ON I I B+ Ignition switch ON Coolant fan relay B+ . - Other conditions lgnition switch On dround data link connector TEN terminal I Blow 1.0" I B+ Vehicle speed sensor ldle switch OFF While driving Vehicle sto~wed ldle switch (in throttle position sensor) 2-5V 1 or 7V . , Accelerator pedal released Accelerator ~edal de~ressed - Stoplight switch OV B+ Brake pedal released Brake ~edal deoressed lgnition switch ON Steering pressure sensor OV B+ I I - Ignition switch ON B+ - PIS ON (at idle) PIS OFF (at idle) Air conditioning sensor Air conditioning sensor ON (Igni- tion switch ON) Air conditioning sensor OFF (Igni- tion switch ON) OV B+ - Below 2.5V B+ Blower motor ON Gartner Banana