1994 MAZDA MX-5 air condition

ENGINE TUNE-UP ENGINE TUNE-UP PREPARATION L" SST r I I 16EOF2-012 BASIC INSPECTION Engine Oil 1. Remove the dipstick and check the engine oil level and condition. 2. Add or change oil as necessary. 49 B019 9AO System Selector Coolant (engine cold) For inspection of ignition timing and idle speed Warning Removing the radiator cap or the coolant drain plug while the engine is running, or when the en- gine and radiator are hot is dangerous. Scalding coolant and steam may shoot out and cause seri- ous injury. It may also damage the engine and cooling system. Turn off the engine and wait until it is cool. Even then, be very careful when remov- ing the cap. Wrap a thick cloth around it and slow- ly turn it counterclockwise to the first stop. Step back while the pressure escapes. When you're sure all the pressure is gone, press down on the cap-still using a cloth-turn it, and remove it. 1. Verify that the coolant level is near the radiator filler neck. 2. Verify that the coolant level on the coolant dipstick is be- tween the F and L marks. 3. Add coolant if necessary. Battery Removing the label on the top of the battery or removing the vent caps will void the battery's warranty. 1. Clean any corrosion on the clamps or battery posts. 2. Verify that the battery top is clean. If necessary, clean with baking soda and water. 3. Verify that cables are in good condition and not frayed or corroded. Repair or replace if necessary. 4. Verify that cable clamps are tight. Note Because this is a maintenance free battery, it is not necessary to check the fluid level. Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM CODE No. 25 (PRC SOLENOID VALVE) I Condition Ignition switch ON ACTION Repair connector and/or wiring harness Go to next step Go to next step STEP 1 2 Check for open or short circuit in wiring harness (PRC Battery positive solenoid valve terminal A - Main relay terminal D) voltaae 3 CODE No. 26 (PURGE SOLENOID VALVE) iTEP I INSPECTION I ACTION 4 ' I Are there any poor connections in purge solenoid valve circuit? INSPECTION I . - I Is continuity between PRC solenoid valve terminal B and PCME terminal 2R? I 2 Is resistance of purge solenoid valve OK? Does PRC solenoid valve circuit have a poor con- nection? Is connector terminal A voltage OK with PRC sole- noid valve connector disconnected? 36UOF2-039 Is PRC solenoid valve OK? as page F-123 Is there battery positive voltage at terminal A of purge solenoid valve circuit? Yes No Yes Yes Solenoid valve Check for short circuit in wiring harness (PRC solenoid valve terminal B - PCME terminal 2R) No Yes ' No 5 Is PCME terminal 2X voltage OK? page F-147 Q If OK, go to next step e If not OK, repair wiring harness Repair wiring harness Replace PCME page F-143 Replace PRC solenoid valve Yes Repair or replace connector No Go to next step Yes Go to next step No Replace purge solenoid valve page F-132 Yes Go to next step No Check for open circuit in wiring from purge solenoid valve I to main relay I No Check for open circuit in wiring from purge solenoid valve I to PcME I Yes I Replace PCME page F-143 No Check for short circuit in wiring from purge solenoid valve to PCME 15UOF2-035 Gartner Banana

F ON-BOARD DIAGNOSIS SYSTEM CODE NO. I 28 (EGR SOLENOID VALVE(VACUUM)) I I iTEP I INSPECTION ACTION (vacuum) circuit? valve (vacuum) connector disconnected OK? - Yes Repair or replace connector I Go to next step Yes Go to next step No - Yes - No 3 Check for open or short circuit in wiring from EGR solenoid valve (vacuum) terminal A to main relay terminal I Condition 1 Voltage IG switch ON I Battery positive voltage Is continuity between EGR solenoid valve (vacu- um) terminal B and PCME terminal IT OK? Check for short circuit in wiring from EGR solenoid valve (vacuum) terminal B to PCME terminal IT 0 If OK, go to next step 0 If not OK, repair or replace wiring harness Repair or replace wire harness Yes - No 4 Replace PCME Replace EGR solenoid valve (vacuum) Is EGR solenoid valve (vacuum) OK? CODE No. I - 29 (EGR SOLENOID VALVE(VENT)) I iTEP I INSPECTION ACTION I I If there a poor connection in EGR solenoid valve (vent) circuit? Repair or replace connector Go to next step Go to next step 1 Is connector terminal A voltages with EGR solenoid valve (vent) connector disconnected OK? Check for open or short circuit in wiring from EGR solenoid valve (vent) terminal A to main relay terminal I Condition I Voltage G switch ON I Battery positive voltage 1 Yes 3 Check for short circuit in wiring from EGR solenoid valve (vent) terminal B to PCME terminal 1 R Is continuity between EGR solenoid valve (vent) terminal B and PCME terminal 1 R OK? 0 If OK, go to next step s If not OK, repair or replace wiring harness Re~air or reolace wire harness I 4 Replace PCME I Replace EGR solenoid valve (vent) 39UOFX-110 Is EGR solenoid valve (vent) OK? No Yes No Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM SWITCH MONITOR FUNCTION Inspection Procedure POWERTRAIN CONTROL MODULE (ENGINE) NEUTRAL SWITCH CLUTCH SWITCH 1 STOPLIGHT SWITCH HEADLIGHT SWITCH REAR WINDOW DEFROSTER SWITCH PARKINEUTRAL SWITCH IDLE SWITCH (IN THROTTLE POSITION SENSOR) BLOWER SWITCH AIR CONDITIONING SENSOR I ' SYSTEM MONITOR LAMP (SELF-DIAGNOSIS 1 Clutch switch (MT) 1 Pedal released I Pedal depressed I In gear I Switch Self-Diagnosis Checker (Monitor lamp) I Liaht ON Liaht OFF . . I I I - I Idle switch (in throttle position sensor) I Pedal depressed I Pedal released 1 Remark ParWneutral switch (AT) I L, S, D and R range I N and P range I I I Stoplight switch (MT) Pedal depressed I Pedal released - I Neutral I Clutch pedal released Neutral switch (MT) - In gear I I Blower switch Headlight switch OFF Blower motor position: "medium" "high" or "super hiah" position I I ON 1. Connect the SST to the data link connector as shown. 2. Turn the ignition switch ON. Check if the monitor lamp il- luminates when each switch is made to function as de- scribed below. If any switch remains activated, the monitor lamp will be illuminated. 3. Connect the SST to the data link connector as shown. 4. Turn the ignition switch to ON (engine off). Check if the monitor lamp illuminates when each switch is adjusted as described above. 45UOFX-173 OFF 1 Air conditioning sensor Rear window defroster switch - ON ON OFF OFF Fan speed control: Low position - Gartner Banana

F ON-BOARD DIAGNOSIS SYSTEM Procedure - Set conditions to deactivate each switch a All accessories OFF a Transmission in neutral a All pedals released Verify that monitor lamp does not illuminate Neutral and Clutch switches (MT) Parklneutral switch (AT) Depress clutch pedal Verify that monitor lamp does not illuminate Return transmission to neutral NO PC: a Neutral or clutch switch malfunction (Refer to F-146) a Open circuit in related wire harness a Powertrain control module (engine) terminal 1V malfunction (Refer to page F-146) - Shift transmission into gear Verify that monitor lamp illuminates with clutch pedal is re- leased PC: a Clutch switch malfunction (Refer to page F-157) 35UOFX-046 I ParWneutral switch OK Shift into P or N range Check each switch and related wire harness a Clutch and Neutral switch :Refer to page F-I57 a Idle switch (in throttle position sensor) :Refer to page F-154 a Stoplight switch :Refer to Section T Headlight switch :Refer to Section T 1 Check each switch as described I I NO - ldle switch (in throttle position sensor) a Blower switch :Refer to Section T a Air conditioning sensor :Refer to Section U a Rear window defroster switch :Refer to Section T a ParWneutral switch :Refer to Section K YES PC: a ParWneutral switch malfunction (Refer to Section K) a Open or short circuit in related wire harness a PCME terminal 1 V voltage incorrect (Refer to page F-I 46) PCME malfunction - Shift transmission into L, S, D, or P range Check that monitor lamp illuminates 35UOFX-06 NO + YES I 1 I ldle switch OK I L I PC: Throttle position sensor malfunction (Refer to page F-144) a Short circuit in wire harness from throttle position sensor to PCME a PCME terminal 1 N voltage incorrect (Refer to page F-145) a PCME malfunction - Depress accelerator pedal and check that monitor lamp illu- minates f NO --c YES PC: a Throttle position sensor malfunction (Refer to page F-144) Open circuit in wire harness from throttle position sensor to PCME PCME terminal 2M voltage incorrect (Refer to page F-146) Release acceleration pedal and check that monitor lamp does not illuminate 2 YES I I Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM Stoplight switch OK Release brake pedal Stoplight switch (MT) Headlight switch PC: Stoplight switch malfunction (Refer to Section T) 0 Open circuit in wire harness from stoplight switch to powertrain control module (engine) Powertrain control module (engine) terminal 10 malfunction (Refer to page F-145) Headlight switch OK Turn OFF headlight switch I I NO ---c L, Blower switch YES Depress brake pedal and verify that monitor lamp illuminates PC: Headlight switch malfunction (Refer to section T) Open circuit in wire harness from headlight switch to powertrain control module (engine) Powertrain control module (engine) terminal 1 U malfunction (Refer to page F-146) Turn ON headlight switch Verify that monitor lamp illuminates Verify that monitor lamp illuminates NO - I YES YES Blower switch OK Turn OFF blower switch Air conditioning sensor PC: Blower switch malfunction (Refer to section T) 0 Open circuit in wire harness from blower switch to powertrain control module (engine) 0 Powertrain control module (engine) terminal IS malfunction (Refer to page F-146) 1 I YES I ' Set fan speed control to low position Turn air conditioning sensor ON, and verify that monitor lamp illuminates PC: Air conditioning sensor malfunction (Refer to Section U) Blower switch malfunction Open circuit in wire harness from air conditioning sensor to blower switch Powertrain control module (engine) terminal 1Q malfunction (Refer to page F-146) NO' 4 Air conditioning sensor OK Turn air conditioning sensor and blower switch OFF Rear window defroster switch Turn rear window defroster switch ON Is monitor lamp illuminated? NO PC: Rear window defroster switch malfunction (Refer to Section T) Open circuit in wire harness (Rear window defroster switch - PCME) PCME terminal 2L voltage incorrect (Refer to page F-146) PCME malfunction YES Turn rear window defroster switch OFF u Rear window defroster switch OK Gartner Banana

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

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