SECTION T MAZDA MX-5 1994 Repair Manual

F TROUBLESHOOTING GUIDE I [TROUBLESHOOTING HINTS] Hinh sulfur content fuel used 29 ISTEP l INSPECTION I ACTION I EXHAUST SULFUR SMELL I 1 I Chanae fuel to another brand I DESCRIPTION I Exhaust gas smells abnormal (Rotten egg smell) 30 I HIGH OIL CONSUMPTION TROUBLESHOOTING HINTS] D PCV system malfunction ne malfunction (Oil working up, working down, or leakage) INSPECTION Check if PCV hose, ventilation hose or their attach- ing nipples are separated, damaged, clogged, or restricted L@? page F-130 Check if air pressure or oil is present at ventilation hose VENTILATION Check if vacuum is felt at PCV valve at idle page F-130 Yes - No - Yes No - Yes ACTION Repair or replace e page F-122 Go to next step Go to next step Check engine condition Oil leakage Worn valve seal Worn valve stem Worn valve guide Section B Check engine condition Section B Worn piston ring groove Stuck piston ring Worn piston or cylinder Replace PCV valve page F-130 Gartner Banana

TROUBLESHOOTING GUIDE F POOR FUEL ECONOMY I [TROUBLESHOOTING HINTS] Nhile fuel consumption is drastically increased during city driving, short-run operation, stop and go driving, extended winterwarm- ~p periods, etc., as opposed to "trip" mileage, an attempt should be made to determine these factors when confronted with "poor mileage" conditions. However, since the operator is not always at fault, the following is offered. 3 Operator depressing accelerator more than usual due to O Alcohol blended fuel used low engine power @ High vehicle load Poor ignition Low tire pressure Low intake air amount Unrecommended tire used Electric spark advance control malfunction Brake dragging Clutch slipping @ Fuel cut control malfunction Exhaust component restricted @ High idle speed AirIFuel mixture too rich High fuel line pressure INSPECTION Check factors other than engine Low tire pressure Section Q Unrecommended tire used @zT Section Q Clutch slipping Section H Brake dragging Section P Exhaust component restricted @zT page F-128 ACTION - Yes Go to next step Repair Check if air hoses are connected correctly @zT page F-99 Yes - No Go to next step Repair @zT page F-99 Check if air cleaner element is clean page F-76 Yes - No Go to next step Replace page 699 Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON @zT page F-79 Yes Go to next step SELECT SW A SYSTEM SELECT 1 Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage US page F-145 Specification: Battery positive voltage (Ignition switch ON) 6 If OK, replace PCME page F-143 6 If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Check switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON page F-95 SELECT SW A Yes Go to next step ~~p Lamp not ONIOFF with specified switch Check for cause (Refer to specified check sequence) @zT page F-96 Lamp always ON Check wiring between PCME terminal 1 F and Self-Diag- nosis Checker us page F-7 Gartner Banana

TROUBLESHOOTING GUIDE IT- MIL ALWAYS ON I ( DESCRIPTION I Self-Diagnosis Checker does not indicate Diagnostic Trouble Code No. but MIL always ON I I - - [TROUBLESHOOTING HINTS] Short circuit in wiring harness PCME malfunction ISTEP l INSPECTION I ACTION I 1 STEP 33 Disconnect (1 E) wire from PCME and check if MIL goes off 1 E MIL NEVER ON Ground (1 E) wire at PCME with jumper wire and check if MIL comes on 1 E Self-Diagnosis Checker indicates Diagnostic Trouble Code No. of input device but MIL never ON DEscR~pT~O~ I : Other indicator and warning lamps OK [TROUBLESHOOTING HINTS] Bulb burned out Open circuit in wiring harness PCME malfunction INSPECTION Yes No ACTION c3 If OK, replace PCME page F-143 I Q If not OK, repair PCME connector Replace PCME page F-143 Check for short circuit in wiring between combination me- ter and PCME page F-7 Yes No Check if bulb is OK I I Check connection condition of PCME connector tw page F-144 I r> If OK, repair (1 E) wire between PCME and combination meter as= page F-7 c3 If not OK, replace bulb Section T Gartner Banana

F TROUBLESHOOTING GUIDE DESCRIPTION I Blower fan operates but cool air not expelled ITROUBLESHOOTING HINTS] Open or short circuit in wiring harness NC relay malfunction 34 Air conditioning sensor malfunction Magnetic clutch malfunction PCME malfunction AIC DOES NOT WORK INSPECTION ;round terminal B at NC relay with jumper wire Yes tnd check if condenser fan operates when ignition ;witch is turned ON #C RELAY I ;round terminal B at PCME 1 J terminal with jump- Yes ,r wire and check if condenser fan operates when gnition switch is turned ON - No :heck if Air conditioning sensor is OK Yes Section U ACTION 30 to next step 30 to A/C system Troubleshooting Section U 30 to next step qepair wire between PCME and A/C relay page F-7 Try known good PCME page F-144 ;heck Air conditioning sensor and wiring Section U Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM Troubleshooting If a diagnostic trouble code number is shown on the SST, check for the cause by using the chart related to the code number shown. CODE NO. 01 (IGF-SIGNAL) 1 Are there any poor connections at ignition coil con- nectors? 2 STEP 1 INSPECTION Does tachometer operate? 3 = 1 Is there continuity between ignition coil terminal C and ground? ACTION Is resistance of ignition coil OK? Resistance: Secondary 8.7-1 2.9 kQ 4 1 Are PCME terminals 1 G and 1 H voltages OK? @s page F-145 Is ignition coil terminal A voltage OK? Section G Circuit Diagram IGNITION COIL (IGNITER) Yes 1 Repair or replace connector I No Yes Go to next step Go to next step No Yes Check for open circuit in wiring from ignition oil to PCME terminal 21 Go to next step No Yes Yes I Replace PCME page F-143 I Replace ignition coil rn Section G Go to next step No Yes No - - No I Check for circuit in wiring from ignition coil to PCME I 35UOFX-043 Check for open circuit in wiring from ignition coil to ignition switch Go to next step Check for open circuit in wiring from ignition coil to ground DATA LINK - . . . . . - . . CONNECTOR 9 3 PCME 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

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