1994 MAZDA MX-5 SECTION T

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

INTAKE AIR SYSTEM INTAKE AIR SYSTEM COMPONENTS Removal 1 Inspection l Installation Warning Fuel vapor is hazardous. It can very easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. Fuel in the fuel system is under high pressure when the engine is not running. Warning Fuel line spills and leaks are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete the follow- ing "Fuel Line Safety Procedures". Fuel Line Safety Procedures A. Release the fuel pressure before disconnecting a fuel line. 1. Start the engine. 2. Remove the fuel pump relay. 3. After the engine stalls, turn the ignition switch to OFF. 4. lnstall the fuel pump relay. B. Avoid leakage. 1. When disconnecting a fuel line hose, wrap a rag around it to protect against fuel leakage. 2. Plug the hose after removal. C. lnstall hose clamps to secure the fuel pressure gauge connections. 1. Drain the engine coolant. (Refer to section E.) 2. Remove in the order shown in the figure. 3. Check the components for damage and repair or replace as necessary. 4. lnstall in the reverse order of removal, using new gaskets. 5. Refill the engine coolant. (Refer to section E.) Gartner Banana

FUEL SYSTEM FUEL TANK Removal 1 Inspection / Installation b Warning Fuel vapor is hazardous. It can very easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. Warning Fuel line spills and leaks are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete the "Fuel Line Safety Procedures" on page F-108. Warning Repairing a fuel tank that has not been properly steam cleaned can be dangerous. Explosion or fire may cause death or serious injury. Always properly steam clean a fuel tank before re- pairing it. 1. Disconnect the negative battery terminal. 2. Drain the fuel from the fuel tank. 3. Remove the main silencer. (Refer to page F-128.) 4. Remove the power plant frame. (Refer to section J.) 5. Remove in the order shown in the figure, referring to Removal note. 6. Install in the reverse order of removal, referring to Installation note. Gartner Banana

FUEL SYSTEM Installation note Fuel hoses and fuel filler hoses Push the ends of the main fuel hose, fuel return hose, and evaporation hose onto the fuel tank fittings L at least 25mm (1.0 in). Push the fuel filler hose onto the fuel tank pipe and filler pipe at least 35117171 (1.4 in). Power plant frame Install the power plant frame referring to the installation procedure on section J. FUEL FILTER Replacement Low-pressure side (In-tank filter) (Refer to page F-116.) High-pressure side The fuel filter must be replaced at the intervals outlined in the maintenance schedule. Warning Fuel vapor is hazardous. It can very easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. Warning Fuel line spills and leaks are dangerous. Fuel can ~SJOFX-226 ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete the "Fuel Line Safety Procedures" on page F-108. 1. Raise the rear of the vehicle and support it with safety stands. 2. Remove the fuel filter protector. 3. Disconnect the fuel hoses from the fuel filter. 4. Remove the fuel filter and bracket. 5. Install in the reverse order of removal. 6. Verify that the fuel hoses are pushed fully onto the fuel filter nipples. Tightening torque: 7.9-10.7 N.m (80-110 kgfam, 70-95.4 in-lbf) 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 Check Point for Each Terminal B+: Battery positive voltage Terminal -. - Connection to Abnormal voltage Possible cause Battery Always OV (Battery OK) Always OV Main relay a ROOM 10A fuse burned Open circuit in wiring from ROOM 1 OA fuse to PCME terminal 1A Main relay malfunction (Refer to page F-156) Open circuit in wiring from main relay to PCME termi- nal 1 B Ignition switch (Start position) a Main relay malfunction (Refer to page F-156) Open circuit in wiring from main relay to data link connector terminal +B Open or short circuit in wiring from data link connec- tor terminal MEN to PCME terminal 1 D Always OV (Starter turns) Always OV Open circuit in wiring from starter interlock switch to PCME terminal 1 C Self-Diagnosis Checker (Monitor lamp) Always B+ a Poor connection at PCME connector PCME malfunction I Always approx. 5V I a PCME malfunction Malfunction indicator light (MIL) Always below 2.5V (MIL always ON) Always below 2.5V Open circuit in wiring from combination meter to (MIL never ON) I PCME terminal I E a Short circuit in wiring from combination meter to PCME terminal 1 E PCME malfunction Always B+ Poor connection at PCME connector a PCME malfunction Self-Diagnosis Checker (Code No.) Always below 2.5V (No display on Self-Diagnosis Checker) Main relay malfunction (Refer to page F-156) a Open circuit in wiring from main relay to data link connector terminal +B Always B+ Always below 2.5V ("88" is displayed and buzzer sounds continuously) a Poor connection at PCME connector a PCME malfunction - Open or short circuit in wiring from data link connec- tor terminal FEN to PCME terminal I E Igniter Always OV a Refer to Code No.01 troubleshooting I (Refer to section GI Powertrain control module (transmission) Always B+ I PCME malfunction A/C relay malfunction (Refer to section U) a Open circuit in wiring from main relay to NC relay a Open circuit in wiring from NC relay to PCME termi- nal 1 J a Short circuit in wiring from NC relay to PCME termi- nal 1 J a PCME malfunction Always below 2.5V (NC does not operate) Always below 2.5V (Air conditioning sensor OFF but A/C operates) AIC relay Air conditioning sensor malfunction (Refer to section U) Poor connection at PCME connector PCME malfunction Always B+ Open circuit in wiring from PCME terminal 1 K to ground PCME malfunction Ground (MT) Always B+ Open (AT) Always OV Short circuit in wiring from PCME terminal 1 K to grounc PCME malfunction Coolant fan relay Always below 1 .OV (Coolant fan OK) Open or short circuit in wiring from fan relay to PCME terminal I L PCME malfunction Gartner Banana

CONTROL SYSTEM B+: Battery positive voltage Terminal 1 M 7 1 N 10 1 P 1 Q 1 R 1 S 1 T 1 U Connection to Abnormal voltage Always approx. 1 V Always approx. 7V Possible cause r Vehicle speed sensor malfunction r Short circuit in wiring from vehicle speed sensor to PCME terminal 1 M Vehicle speed sensor - r Vehicle speed senso~malfunction r Open circuit in wiring from vehicle speed sensor to PCME terminal 1 M r Throttle position sensor misadjustment (Refer to page F-154) r Short circuit in wiring from PCME terminal 1 N to throttle position sensor 6 PCME malfunction Always OV Throttle position sensor (idle terminal) Always B+ r Throttle position sensor misadjustment (Refer to page F-154) r Open circuit in wiring from PCME terminal 1 N to throttle position sensor r Open circuit in wiring from throttle position sensor to ground Stoplight switch Always OV (Stoplights OK) r Open circuit in wiring from stoplight switch to PCME terminal 10 r Steering pressure sensor malfunction (Refer to page F-158) Short circuit in wiring from PCME terminal 1 P to steering pressure sensor r PCME malfunction r Steering pressure sensor malfunction (Refer to F-158) r Open circuit in wiring from PCME terminal 1 P to steering pressure sensor Open circuit in wiring from steering pressure sensor to ground r Air conditioning sensor malfunction (Refer to section U) r Short circuit in wiring from PCME terminal 1 Q to air conditioning sensor r Poor connection at PCME connector r PCME malfunction Always OV Steering pressure sensor Always B+ -- Air conditioning sensor Always OV (with blower switch ON) Air conditioning sensor malfunction (Refer to section U) Open circuit in wiring from PCME terminal 1Q to air conditioning sensor Open circuit in wiring from air conditioning sensor to blower switch Always B+ (with blower switch ON) (Blower fan OK) EGR solenoid valve (vent) Always OV r Refer to Code No.29 Troubleshooting (Refer to page F-92) Short circuit in wiring from blower switch to PCME terminal 1 S r Poor connection at PCME connector PCME malfunction Always OV (Blower fan OK) Blower switch Always B+ (Blower fan OK) Open circuit in wiring from blower switch to PCME terminal IS EGR solenoid (vacu- um) Always OV r Refer to Code No.28 Troubleshooting (Refer to paae F-92) Headlight switch Always OV (Headlights OK) r Open or short circuit in wiring from headlight relay to PCME terminal 1 U Gartner Banana

F CONTROL SYSTEM B+: Battery positive voltage Abnormal voltage Possible cause Terminal 1 v Connection to Neutral switch malfunction (Refer to page F-157) Clutch switch malfunction (Refer to page F-156) Short circuit in wiring from PCME terminal 1 V to neutral or clutch switch Neutral switch malfunction (Refer to page F-157) 0 Clutch switch malfunction (Refer to page F-156) 0 Open circuit in wiring from PCME terminal 1 V to neutral or clutch switch Poor connection at PCME connector 0 ParWneutral switch malfunction (Refer to section K) 0 Short circuit in wiring from parWneutral switch to PCME terminal 1V 0 ParWneutral switch malfunction (Refer to section K) 0 Open circuit in wiring from parWneutral switch to PCME terminal 1 V Always OV Neutral switchlClutch switch (MT) Always B+ Always OV ParWneutral switch (AT) Always B+ Poor contact at ground terminal 0 Open circuit in wiring from PCME to ground Sround More than OV Crankshaft position sensor (SGT-signal) Always OV or approx. 5V Always below 2V or 4V Refer to Code No.03 troubleshooting (Refer to page F-84) Refer to code No.08 Troubleshooting (Refer to page F-86) 0 Short circuit in wiring from PCME terminal 2H to data link connector terminal TEN Mass airflow sensor Always OV Data link connector (Terminal TEN) 0 Open circuit in wiring from PCME terminal 2H data link connector terminal TEN 0 Open circuit in wiring from data link connector terminal GND to around Always B+ Igniter EGR function sensor Always OV Always approx. OV or approx. 5v Refer to Code No.01 troubleshooting (Refer to paae F-83) 0 Refer to Code No.16 Troubleshooting (Refer to page F-89) 0 Short circuit in wiring from PCME terminal 2K tothrottle position sensor, PCME, or mass airflow sensor Poor connection at PCME connector PCME malfunction Vre f Always OV lllumination light ON when rear window defroster switch ON Open or short circuit in wiring from rear window de- froster switch to PCME terminal 2L Always below 1 .ov Rear window defroster switch Open circuit in wiring from ignition switch to rear win- dow defroster switch Rear window defroster switch malfunction (Refer to section T) lllumination light never ON Open circuit in wiring from PCME terminal 2M to throttle position sensor 0 Open circuit in wiring from PCME terminal 2K to throttle position sensor 0 Open circuit in wiring from PCME terminal 20 to throttle position sensor Always constant Throttle position sensor Alwavs above 1V 0 Throttle position sensor misadjustment Refer to Code No.15 troubleshooting (Refer to page F-88) OV after warm-up Heated oxygen sensor Always approx, 1V after warm-up 0 Refer to Code No.17 troubleshooting (Refer to page F-90) Refer to Code No.08 troubleshooting (Refer to page F-86) Mass airflow sensor Always OV or approx. 5V Gartner Banana