engine MAZDA MX-5 1994 Workshop Manual

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

CONTROL SYSTEM CONTROL SYSTEM PREPARATION 49 9200 162 Engine Signal Monitor Self-Diagnosis Checker 49 GO1 8 904 Sheet For inspection of powertrain control module (engine) For inspection of heated oxygen sensor For inspection of powertrain control module (engine) 49 GO18 903 For inspection of Adapter powertrain harness control module 49 B019 9AO For inspection of System heated oxygen Selector sensor 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 POWERTRAIN CONTROL MODULE (ENGINE) (PCME) Removal l Installation 1. Remove in the order shown in the figure. L 2. Install in the reverse order of removal. 1. Negative battery cable 2. PCME connector 3. PCME Inspection . . . . . . . . . . . . . . . . . . page F-144 Gartner Banana

F CONTROL SYSTEM Inspection 1. Lift up the floormat in front of the passenger's seat. (Refer to section S.) ,i 1 USECONNECTORA TERMINALS /AANDB 2. Connect the SST (Engine Signal Monitor) between the powertrain control module (engine) and the wiring har- ness using the SST (Adapter) as shown. 3. Place the SST (Sheet) on the SST (Engine Signal Mon- itor). 4. Measure the voltage at each terminal. (Refer to pages F-148 to F-151.) 5. If any powertrain control module (engine) terminal volt- age is incorrect, check the input or output device and re- lated wiring. 6. If they are normal, replace the powertrain control module (engine). (Refer to pages F-145 to F-147.) Caution Applying voltage to SST terminals A or B will dam- age the SST. 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

F CONTROL SYSTEM B+: Battery positive voltage Connection to 1 Test condition 1 Voltage I Remark I -- EGR solenoid valvi Idle B+ Blower switch -- EGR solenoid valve (vacuum) :vent) Initial acceleration* Blower switch at mid, high or su- per high position Blower switch OFF or low Headlight switch Neutral or clutch switch (MT) B+ Idle ParWneutral switch (AT) Ground (Injector) Ground (Output) Ground (PCME) Approx. OV - Approx. 12V B+ Headlights ON (Tail, parking, low beamfhigh beam) Headlights OFF Neutral position or clutch pedal de- pressed Other conditions Ground (Input) Crankshaft position (SGT-signal) Ignition switch ON N or fJ range Other conditions Constant Constant Constant -. Mass airflow sensor .. . . EGR function sensor I while running Approx. 0-5v Initial acceleration* Approx, 2V OV ov B+ Constant Ignition switch ON Idle Crankshaft position sensor (SGC-signal) Data link connector (TEN terminal) Igniter I I I Vre f I lanition switch ON 1 4.5-5.9.' 1 - B+ - OV B+ OV OV OV Ignition switch ON Idle - - - OV OV or 5V ADD~OX. 2V - - Ignition switch ON Idle System Selector test switch at "02 MONITOR" System Selector test switch at "SELF-TEST" Ignition switch ON Idle lanition switch ON I . . I I 1 Ignition switch ON I Below 1 .OV I I - - . . Below 1 .OV Below 1 .OV ear window defrost- er relay Throttle position sensor Heated oxygen sensor - OV or 5V Approx. 1.5V B+ ov Below 0.5V Approx. 1 V Approx. 1 .OV - - - " Rear window defroster switch OFF Rear window defroster switch ON Accelerator pedal released Accelerator ~edal fullv de~ressed Mass airflow sensor B+ Below 1 .OV 0.1-1 .o 3.14.5 Intake air temperature sensor Engine coolant tem- perature sensor lgnition switch ON lgnition switch ON Ignition switch ON Idle ireen and red lamps flash At 200C {680Fj Engine coolant temperature 20°C {680F) After warm-up Below 1 .OV 1 .O-2.0 - Approx. 2.5V Approx. 2.5V Approx. 0.4V Built in mass airflow lgnition switch ON Gartner Banana

CONTROL SYSTEM F Connection to I Test condition I Hot condition: Enaine coolant Input - temp. above 70°C (1 58"~) and in- PRC solenoid valve take air temp. above 50°C (122°F) for 150 sec. after enaine startina Output 0 0 0 0 0 0 0 0 0 " " Other conditions lanition switch On - Condenser fan relay Engine coolant temp. Idle above 108°C 1226°F) I I Other conditions ' I lgnition switch ON Fuel pump relay ldle I I lanition switch ON Fuel injector No.1 1,900 rpm (After warm-UD) I lgnition switch ON Fuel injector No.2 ldle Deceleration from 3,000 rprn to 1,900 rpm (After warm-up) lgnition switch ON IAC valve ldle lgnition switch ON Purge solenoid valve ldle Fuel injector No.3 lgnition switch ON ldle Deceleration from 3,000 rpm to 1,900 rpm (After warm-up) lanition switch ON Fuel injector No.4 Idle Deceleration from 3,000 rpm to 1,900 rpm (After warm-up) Below 1 .OV -1 Below 1 .OV B+ - Approx. OV Engine Signal Moni- * Engine Signal Moni- tor: Green and red Approx. 12V I lamps flash B+: Battery positive voltage Voltage I Remark * Engine Signal Moni- tor: Green and red Engine Signal Moni- Gartner Banana

CONTROL SYSTEM B+: Battery positive voltage Terminal Connection to Abnormal voltaae Possible cause Mass airflow sensor (Intake air temperature sensor) Refer to Code No.10 troubleshooting (Refer to page F-87) Always OV or approx. 5V Intake air temperature sensor malfunction (Refer to page F-152) Refer to Code No.09 troubleshooting (Refer to page F-87) Engine coolant temper- ature sensor Always OV or approx. 5V r Engine coolant temperature sensor malfunction (Refer to page F-154) Refer to Code No.25 Troubleshooting (Refer to page F-91) Always OV or B+ PRC solenoid valve r Open or short circuit in wiring from condenser fan relay to PCME terminal 25 PCME malfunction Open or short circuit in wiring from fuel pump relay to PCME terminal 2T Condenser fan relay Always below 2.OV Fuel pump relay Always below 1 .OV Main relay malfunction (Refer to page F-156) r Open or short circuit in wiring from fuel injector to PCME terminal 2U or 2V Always OV Fuel injector ldle air control valve Purge solenoid valve Always B+ Always OV or B+ Always OV or B+ PCME malfunction r Refer to Code No.34 troubleshooting (Refer to page F-93) ldle air control solenoid valve malfunction (Refer to page F-I 06) r Refer to Code No.26 troubleshooting (Refer to page F-91) r Purge solenoid valve malfunction (Refer to pane F-132) -- Fuel injector Always OV Main relay malfunction (Refer to page F-156) Open or short circuit in wiring from fuel injector to PCME terminal 2Y or 22 Always B+ PCME malfunction Gartner Banana

CONTROL SYSTEM --- 1 1 USE CONNECTOR A C (INTAKE AIR D (GROUND) TEMPERATURE MASS AIRFLOW SENSOR lnspection Visual inspection d Caution Do not drop subject the sensor to sharp shocks. Do not put or allow anything in the sensor. 1. Disconnect the mass airflow sensor connector. 2. Remove the'mass airflow sensor. 3. Check for damage of the sensor. 4. Install the mass airflow sensor. Voltage inspection 1. Disconnect the PCME connectors. 2. Connect the SSTs (Engine Signal Monitor and Adapt- er Harness) to the PCME as shown. 3. Place the SST(Sheet) on the SST (Engine Signal Mon- itor). 4. Check the voltage of terminals 20 and 2F. Specification I 2F I Below 1 .OV I 5. If not as specified, replace the mass airflow sensor. Idle 1 .O-2.OV 20 Tightening torque: u 7.9--10.7 N.m (80-11 0 kgfncm, 70-95.4 in-lbf} 10 ON Below 1 .OV Inspection Intake air temperature sensor 1. Verify that the ignition switch OFF. 2. Disconnect the mass airflow sensor connector. 3. Measure resistance of the intake air temperature sensor as shown. Specification: 2.21-2.69 (at 20°C (68°F)) 4. If not as specified, replace the mass airflow sensor. Gartner Banana