1994 MAZDA MX-5 wiring

TROUBLESHOOTING GUIDE F 24 Overloaded ) Low intake air amount Throttle valve not oDen fully LACK OF POWER ESCRIPmH - TEP - 1 - 2 : Performance poor under load Reduced maximum speed :heck factors other than engine Clutch slipping as Section H Brake dragging Section P Low tire pressure as Section Q Unrecommended tire size Section Q ;heck if throttle valve wide open throttles when lepressing accelerator fully rROUBLESHOOTlNG HINTS] Factors other than engine malfunction O AirlFuel mixture too lean or too rich Clutch slipping Fuel line pressure low or high Brake dragging Insufficient fuel injection Low tire pressure @ Poor ignition Unrecommended tire size 8 Low engine compression >heck if "00 is displayed on Self-Diagnosis Check- !r with ignition switch ON page F-79 :heck switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON as page F-95 SELECT SW A YSTEM SELECT 1 - Yes Yes Clogged intake air system - INSPECTION I - C 0 0 0 0 - c C - ( E -- I I i I I No - Yes No - Yes - No ACTION %to next step 20 to next step Sheck if accelerator cable is correctly installed page F-103 3 If OK, check throttle body @r page F-101 3 If not OK, install accelerator cable correctly page F-103 - 30 to next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage @r page F-145 Specification: Battery positive voltage (Ignition switch ON) o If OK, replace PCME page F-143 O If not OK, check wiring between PCME and Self-Diagno- sis Checker E+T page F-7 Go to next step -- Lamp not ONlOFF with specified switch Check for cause (Refer to specified check sequence) page F-96 Lamp always ON Check wiring between PCME terminal 1 D and Self-Diag- nosis Checker @r page F-7 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION ACTION :heck for correct intake manifold vacuum at idle Iacuum: More than 450 mmHg i17.7 inHg} VACUUM GAUGE / :heck if air cleaner element is clean page F-76 Check for fuel injector operating sound at idle Check if battery positive voltage exists at fuel injec- tor connector B terminal Check if PCME terminal voltages are OK (1 R, 1 T, 2D, 20 and 2Q) page F-146 Check for correct fuel line pressure at idle page F-110 Fuel line pressure: 265--314 kPa i2.7-3.2 kgf/cm2, 38-46 psi) (Vacuum hose to pressure regulator discon- nected) INSTALL CLAPS Yes - No Yes - No - Yes No - Yes Yes No - Yes - No Go to next step -- - --- Check for air leakage of intake air system components r@= page F-100 Go to next step Replace air cleaner element ~8 page F-99 Go to Step 14 Go to Step 13 check if fuel injector resistance is OK page F-119 Resistance: 12-16R 6 If OK, check wiring between PCME and fuel injector E+Y page F-7 6 If not OK, check fuel injector for fuel leakage page F-120 Check wiring between PCME and fuel injector page F-7 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") page F-148 Check if fuel line pressure decreases when accelerating quickly c:, If decreases, check fuel pump maximum pressure @r page F-115 If OK, check fuel line and filter for clogging o If no decreases, go to next step Low pressure Check fuel line pressure while pinching fuel return hose ~2 If fuel line pressure quickly increases, check pressure regulator I@= page F-118 o If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator r@= page F-119 If not clogged, check fuel pump maximum pressure page F-115 Gartner Banana

TROUBLESHOOTING GUIDE TROUBLESHOOTING HINTS] D Factors other than engine malfunction Clutch slipping Brake dragging Low tire pressure Unrecommended tire size 25 O AirIFuel mixture too lean or too rich Fuel line pressure low or high Insufficient fuel injection @ Poor ignition 6 Low engine compression POOR ACCELERATION Overloaded D Low intake air amount Throttle valve not open fully Clogged intake air system )ESCRIPTION I Performance poor while accelerating INSPECTION :heck factors other than engine Clutch slipping Section H D Brake dragging Section P t Low tire pressure Section Q D Unrecommended tire size Section Q :heck if throttle valve wide open throttles when jepressing accelerator fully Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON page F-79 Check switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON page F-95 SELECT SW A SYSTEM SELECT 1 - Yes - No Yes - No - Yes - No Yes - No ACTION Go to next step Repair Go to next step Check if accelerator cable is correctly installed * page 0 If OK, check throttle body ce Page 0 If not OK, install accelerator cable correctly page Go to next step -- Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequenc US page "88" flashes Check PCME terminal 1 E voltage Us Page Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME * Page 9 If not OK, check wiring between PCME and Self- sis Checker * Page Go to next step Lamp not ONlOFF with specified switch Check for cause (Refer to specified check sequenc * Paw Lamp always ON Check wiring between PCME terminal 1 D and Self nosis Checker * Page ! F-103 ! F-101 I F-103 :e) r F-81 ! F-145 I F-143 Diagno- ! F-7 :e) ! F-96 -Diag- ! F-7 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION Sheck if air cleaner element is clean page F-76 1 :: :heck for EGR system malfunction Yes page F-124 Check for fuel injector operating sound at idle Yes Check if battery positive voltage exists at fuel injec- Yes tor connector B terminal Check if PCME terminal voltages are OK [I B, 1 T, 2D, 20 and 2Q) Check for correct fuel line pressure at idle Yes @T page F-110 Fuel line pressure: 265-314 kPa (2.7--3.2 kgf/cm2, 38--46 psi} (Vacuum hose to pressure regulator discon- nected) i INSTALL CLAPS I ACTION Go to next step Replace air cleaner element G= page F-99 Repair or replace Go to next step Go to Step 15 Go to Step 14 Check if fuel injector resistance is OK ccsf page F-119 Resistance: Approx. 12-16R - 0 If OK, check wiring between PCME and fuel injector a? page F-7 O If not OK, check fuel injector for fuel leakage page F-120 Check wiring between PCME and fuel injector ccsf page F-7 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") mzf page F-148 Check if fuel line pressure decreases when accelerating quickly O If decreases, check fuel pump maximum pressure page F-115 If OK, check fuel line and filter for clogging O If no decreases, go to next step Low pressure Check fuel line pressure while pinching fuel return hose 13 If fuel line pressure quickly increases, check pressure regulator mzf page F-118 6 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure @ page F-115 Gartner Banana

TROUBLESHOOTING GUIDE I IESCRIPTION I Engine runs rough while decelerating and abnormal combustion occurs in exhaust system 26 TROUBLESHOOTING HINTS] 3 AirIFuel mixture too rich Air cleaner element clogged Fuel injection control malfunction (Fuel cut control) Fuel injector fuel leakage 0 Ignition timing misadjustment iTEP I INSPECTION RUNS ROUGH ON DECELERATIONIAFTERBURN ;heck if "00" is displayed on Self-Diagnosis Check- ?r with ignition switch ON page F-79 Sheck switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON page F-95 SELECT SW A SYSTEM SELECT 1 Check for correct ignition timing at idle @= page F-76 lgnition timing: 10" 2 lo BTDC Check if fuel cut operation is OK during decelera- tion Fuel cut: Above 1,900 rpm after warm-up Yes Yes Yes - No Yes ACTION Go to next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage 03% page F-145 Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME IGS page F-143 0 If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Go to next step Lamp not ONIOFF with specified switch Check for cause (Refer to specified check sequence) page F-96 Lamp always ON Check wiring between PCME terminal 1 D and Self-Diag- nosis Checker G+F page F-7 Go to next step Adjust page F-76 Go to next step Try known good PCME I@= page F-144 Gartner Banana

TROUBLESHOOTING GUIDE TEP 27 INSPECTION KNOCKING ACTION 30 to next step TROUBLESHOOTING HINTS] > AirIFuel mixture too lean @I Incorrect ignition timing (too advance) Fuel injection amount incorrect Q Overheating Fuel line pressure decreases while accelerating @I Carbon deposits in engine :heck if "00" is displayed on Self-Diagnosis Check- br with ignition switch ON page F-79 Yes Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage uzf page F-145 Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME page 6143 s If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 >heck switches for correct operation with Self- liagnosis Checker Monitor Lamp and ignition ;witch ON as page F-95 SELECT SW A Yes - No Go to next step Lamp not ONIOFF with specified switch Check for cause (Refer to specified check sequence) page F-96 MONl LAMP II- SYSTEM SELECT 1 Lamp always ON Check wiring between PCME terminal 1 D and Self-Diag- nosis Checker uzf page F-7 Zheck if PCME terminal voltages are OK :1R, IT, 2D, 20, and 2Q) page F-146 Yes Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") uzf page F-148 Sheck for correct intake manifold vacuum at idle Yes - No Go to next step Vacuum: More than 450 mmHg (17.7 InHg) VACUUM GAUGE Check for air leakage of intake air system components as page F-100 Check if air cleaner element is clean page F-76 Yes - No Go to next step Replace air cleaner element page F-99 Gartner Banana

TROUBLESHOOTING GUIDE rROUBLESHOOTlNG HINTS] > Poor connection or damaged fuel system or fuel evaporative system 3 Charcoal canister overflow due to fuel evaporative system malfunction 28 INSPECTION Check if fuel leak or damage are visible at fuel sys- tem and fuel evaporative system FUEL ODOR ACTION IESCRIPTION I Gasoline odor in cabin Yes Repair or replace page F-107 30 to next step Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON page F-79 SELECT SW A SYSTEM SELECT 1 I Yes - No - Yes So to next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage page F-145 Specification: Battery positive voltage (Ignition switch ON) o If OK, replace PCME page F-143 o If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Check if vacuum is felt at purge solenoid valve with engine running and throttle valve opened (Neutral switch connector disconnected) Go to Step 5 Check for purge solenoid valve operating sound in this condition o If OK, check vacuum hoses for clogging page F-6 o If not OK, go to next step Apply battery positive voltage and ground to purge solenoid valve and check if air flows through valve Yes Check PCME terminal 2X voltage page F-146 Replace purge solenoid valve @S page F-132 Try known good PCME Daae F-144 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