wiring MAZDA MX-5 1994 User Guide

TROUBLESHOOTING GUIDE ESCRIPTION I 0 Engine cranks at normal speed but requires excessive cranking time (more than 5 sec.) before starting Batterv in normal condition 5 I TROUBLESHOOTING HINTS] D Air/Fuel mixture too lean Q Air/Fuel mixture too rich Fuel injection control malfunction Air cleaner element clogged (Correction for coolant temperature) Mass airflow sensor stuck Low fuel line pressure 31 Poor ignition spark CRANKS NORMALLY BUT HARD TO START - ALWAYS Air leakage STEP - 1 INSPECTION Check if "00" is displayed on Self-Diagnosis Checker with ignition switch ON page F-79 Check for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg (17.7 inHg} VA/CUUM GAUGE Check if air cleaner element is clean page F-76 Check for correct fuel line pressure at idle page F-110 Fuel line pressure: 265--314 kPa (2.7-4.2 kgf/cm2, 38--46 psi} (Vacuum hose to pressure regulator discon- nected) INSTALL CLAPS ' - Yes - No - Yes - No - Yes No - Yes - No - 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 page F-145 Specification: Battery positive voltage (Ignition switch ON) Q If OK, replace PCME page F-143 o If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Go to next step Check for air leakage of intake air system components page F-100 Go to next step Replace air cleaner element page F-99 Go to next step Low pressure Check fuel line pressure while pinching fuel return hose Q If fuel line pressure quickly increases, check pressure regulator page F-118 0 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 INSPECTION ACTION Check if PCME terminal voltages are OK (1 R, 1 T, ZD, 20 and 20) us page F-146 Yes Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") Djp paae F-148 Check if strong blue spark is visible at each discon. nected high-tension lead while cranking engine Yes - No Go to next step Check ignition system (Refer to Troubleshooting "Misfire") Section G Check for EGR system malfunction page F-124 Yes - No Repair or replace Go to next step Check for fuel injector operating sound at each in- Yes Go to Step 10 jector at idle No - Yes Go to Step 9 Check if battery positive voltage exists at fuel injec- tor connector B terminal with ignition switch ON Check if fuel injector resistance is OK page F-119 Resistance: 12-1 6R G If OK, check wiring between injector and PCME page F-7 o If not OK, replace injector L@? page F-119 No - Yes Check wiring between main relay and fuel injector page F-7 Go to next step Check for correct engine compression Section B Engine compression: 1,255-883 kPa I12.8-9.0 kgflcm2, 182-1 28 psi)-300 rpm Check engine condition Section B I Worn piston, piston rings or cylinder wall r Defective cylinder head gasket r Distorted cylinder head r Improper valve seating Valve sticking in guide No - Yes :heck if spark plugs PLUG GAP 1 .O-1 .l mm (0.04+0.043 in} DETERIORATION 30 to next step qepair, clean, or replace Section G Try known good PCME and check if condition im- roves @r page F-144 Gartner Banana

TROUBLESHOOTING GUIDE CRANKS NORMALLY BUT HARD TO START - WHEN ENGINE IS COLD c Engine cranks at normal speed but requires excessive cranking time before starting IESCRIPTION Battery in normal condition Restarts OK after warm-up TROUBLESHOOTING HINTS] D AirIFuel mixture too rich Air cleaner element clogged Idle speed control malfunction Q AirJFuel mixture too lean Fuel injection control malfunction (Correction for coolant temperature) O Poor atomization of fuel Low RVP (summer) fuel used in cold weather INSPECTION Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON page F-79 ACTION - Yes - No - Yes GO to next sGP Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) E+T page F-81 "88" flashes Check PCME terminal 1 E voltage page F-145 Specification : Battery positive voltage (Ignition switch ON) c:, 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 PCME terminal voltages are OK (1 C, 2D, 20 and 2Q) page F-145 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") I@ page F-148 Check if engine starts easily when depressing ac- celerator while cranking Yes Check if idle air control valve is OK @F page F-106 o If OK, check air valve page F-105 6 If not OK, replace IAC valve page F-106 No - Yes - No Go to next step Check for correct intake manifold vacuum at idle Go to next step Vacuum: More than 450 mmHg (17.7 inHg} VACUUM GAUGE / Check for air leakage of intake air system components US= page F-1 00 Check if air cleaner element is clean @&Y page F-76 Yes - No Go to next step Replace air cleaner element page F-99 Try known good PCME and check if condition @&Y page F-144 Yes - No - Replace PCME Change fuel to another brand Gartner Banana

F TROUBLESHOOTING GUIDE [TROUBLESHOOTING HINTS] D AirIFuel mixture too rich 7 Q Vaoor lock CRANKS NORMALLY BUT HARD TO START - AFTER WARM-UP Fuel pressure not held in fuel line after engine stops 0 High RVP (winter) fuel used in warm weather ACTION DESCR'PnON Fuel injection control malfunction Fuel injector fuel leakage Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON uar page F-79 Engine cranks at normal speed but requires excessive cranking time (more than 5 sec.) before starting after run- ning and hot soaked Battery in normal condition Engine starts normally when cold 1 Check if PCME terminal voltages are OK (2D,2R and 2Q) page F-145 INSPECTION Run engine at idle and check if fuel line pressure is held after ignition switch turned OFF page F-109 Fuel line pressure: More than 147 kPa (1.5 kgf/cm2, 21 psi} for 5 min. INSTALL CLAPS Try known good PCME and check if condition im- proves US page F-144 Yes - No Yes - No Yes No - Yes 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 page F-145 Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME @sf page F-143 G If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") page F-148 Go to next step Block outlet of pressure regulator and check if fuel line pressure is held after ignition switch is turned OFF page F-117 If OK, replace pressure regulator page F-118 Q If not OK, check fuel pump hold pressure I@? page F-115 If fuel pump is OK, check fuel injector for fuel leakage page F-120 Replace PCME Change fuel to another brand Gartner Banana

TROUBLESHOOTING GUIDE B ROUGH IDLE - ALWAYS JCRIPTION I Engine vibrates excessively at idle in every condition 'ROUBLESHOOTING HINTS] AirIFuel mixture too lean Air leakage Fuel injection control malfunction Low fuel line pressure Q One or more injectors not operating or clogged O One or more spark plugs not sparking @ Injection timing misadjustment O Low engine compression INSPECTION >heck for correct intake manifold vacuum at idle tacuum: More than 450 mmHg f17.7 inHg} VACUUM GAUGE =heck if air cleaner element is clean page F-76 :heck if "00" is displayed on Self-Diagnosis Check- 3r with ignition switch ON page F-79 SELECTSWA SYSTEM SELECT 1 Sheck switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON SELECT SW A page F-95 Sheck if PCME terminal voltages are OK MONITOR . Sheck i (1 R, IT, 2D, 20 and 2Q) page F-146 - Yes Yes - No - Yes Yes - No - Yes ACTION Go to next step Check for air leakage of intake air system components page F-100 Go to next step Replace air cleaner element page F-99 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 page F-136 Specification: Battery positive voltage (Ignition switch ON) e If OK, replace PCME page F-143 Q If not OK, check wiring between PCME and Self-Diagno- sis Checker 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 as? page F-7 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") us ~aae F-148 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION Check for fuel injector operating sound at idle with sound scope or screwdriver Check if battery positive voltage exists at fuel injec- tor connector 6 terminal Disconnect each high-tension lead at idle and check if engine speed decreases equally each time - - - Check if spark plu CARBON BUILDUP PLUG GAP 1.0-1 .l mm (0.040-0.043 in) DAMAGE AND DETERIORATION Check for correct ignition timing at idle page F-76 Ignition timing: 10" +. lo BTDC Check for EGR system malfunction w page F-124 Check for correct fuel line pressure at idle * page F-110 Fuel line pressure: 26-14 kPa f2.7-3.2 kgflcm2, 38-46 psi} (Vacuum hose to pressure reaulator discon- - Yes - No - Yes No - Yes - No - Yes - No Yes No - Yes ACTION Yes - No - Go to Step 8 Go to Step 7 Check if fuel injector resistance is OK page F-119 Resistance: 12-1 632 0 If OK, check wiring between PCME and fuel injector @r page F-7 Q If not OK, replace fuel injector page F-119 Check wiring between PCME and fuel injector page F-7 Disconnect each fuel injector connector at idle and check if engine speed decreases equally each time 0 If OK, go to Step 10 o If not OK, check fuel injector for fuel leakage G= pane F-120 Go to step 9 Check for correct engine compression t@ Section B Q if OK, replace fuel injector t@ page F-119 o If not OK, check for cause (Refer to Section 6) U=S Section B Repair, clean, or replace Section G Check for correct idle speed @ page F-77 Idle speed: 850 -c 50 rpm (MT) 800 2 50 rpm (AT) 0 If OK, go to next step 0 If not OK, adjust idle speed w page F-77 Adjust page F-72 Repair or replace Go to next step Go to next step Low pressure Check fuel line pressure while pinching fuel return hose 3 If fuel line pressure quickly increases, check pressure regulator US= page F-118 3 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure E+T page F-115 Try known good PCME and check if condition im- proves w Daae F-144 Gartner Banana

TROUBLESHOOTING GUIDE 9 LOW IDLE SPEEDIROUGH IDLE - BEFORE WARM-UP IESCRIPTION I Engine speed low or engine vibrates excessively at idle during warm-up TROUBLESHOOTING HINTS] D Low intake air amount Mass airflow sensor stuck Air cleaner element clogged Idle s~eed control Q Low fuel injection amount Fuel injection control malfunction (Correction for coolant temperature) O Poor atomization of fuel Air valve [Correction for coolant temperature ] iTEP I Low RVP (summer) fuel used in cold weather INSPECTION ACTION - Yes Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON page F-79 GOG next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) trs page F-81 - - "88"flashes Check PCME terminal 1 E voltage page F-145 Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME @ page F-143 e 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 ~8 page F-95 SELECT SW A Yes Go to next step Check if PCME terminal voltaaes are OK No - Yes - No - Yes Lamp not ON/OFF 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 page F-7 Go to next step " (2D, 20 and 2Q) page F-146 Check for cause (Refer to "Check Point for Each Termi- nal") page F-148 Go to next step Check for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg {I?.? inHg) Check for air leakage of intake air system components @ page F-100 INSTALL CLAPS Gartner Banana

TROUBLESHOOTING GUIDE lo 1 LOW IDLE SPEEDIROUGH IDLE - AFTER WARM-UP 3ESCRIPTION I Engine runs normally at idle during warm-up but vibrates excessively after warm-up ;TROUBLESHOOTING HINTS] I> Idle speed control malfunction b AirlFuel mixture too lean Air leakage of intake air system Low fuel line pressure INSPECTION Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON m? page F-79 Check switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON page F-95 SELECT SW A Disconnect idle air control valve connector at idle and check if engine condition is charged IAC VALVE - Yes No - Yes - No Yes O Air/Fuel mixture too rich Fuel injection control malfunction (Correction for coolant temperature) @ Poor ignition spark Q Low engine compression 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 page F-145 Specification: Battery positive voltage (Ignition switch ON) 6 If OK, replace PCME page F-143 Q 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 page F-7 Go to next step Check idle air control valve page F-106 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION >heck if throttle valve is closed throttle position Yes when accelerator released I 11 :heck if "00" is displayed on Self-Diagnosis Check- Yes w with ignition switch ON @? page F-79 HIGH IDLE SPEED - AFTER WARM-UP SELECT SW A SYSTEM SELECT 1 FROUBLESHOOTING HINTS] Excessive intake air supplied to engine O Throttle valve not fully closed @ ldle speed control malfunction Air valve not closing ldle air control valve stuck Incorrect coolant temperature signal STEP 1 >heck switches for correct operation with Self- I Yes liagnosis Checker Monitor Lamp and ignition ;witch ON page F-95 SELECT SW A ACTION Go to next step Check if throttle linkage is correctly installed and operates freely @? page F-103 o If OK, go to next step o If not OK, clean, adjust or replace linkage Daae 6103 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 @S page F-145 Specification: Battery positive voltage (Ignition switch ON) 6 If OK, replace PCME E=T page F-143 o If not OK, check wiring between PCME and Self-Diagno- sis Checker @? page F-7 Go to next step Lamp not ONlOFF with specified switch Check for cause (Refer to specified check sequence) E=T page F-96 am^ always ON Check wiring between PCME terminal ID and Self-Diag- IOS~S Checker @? page F-7 Gartner Banana

TROUBLESHOOTING GUIDE ldle speed control malfunction Engine speed feedback control malfunction ldle air control valve stuck 12 INSPECTION LOW IDLE SPEED - WHEN AIC, PIS, OR EIL ON Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON @? page F-79 SELECT SWA SYSTEM SELECT 1 I Check switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON page F-95 SELECT SW A DESCRIPTIOH MONITOR [LAMP &\L SYSTEM SELECT 1 : Engine speed decreases at idle when NC, PIS, or EIL ON NC, PIS, headlights, blower fan and electric coolant fan operate normally Check if continuity exists between data link con- nector terminal TEN and ground --., rrROUBLESHOOTlNG HINTS] Disconnect idle air control valve connector at idle and check if engine condition is changed IAC VALYE CONNECTOR /' Yes - No Yes Yes No - Yes - No - ACTION Go to next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) US= page F-81 "88" flashes Check PCME terminal 1 E voltage * page F-145 Specification: Battery positive voltage (Ignition switch ON) 6 If OK, replace PCME page F-143 G 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) as page F-96 Lamp always ON Check wiring between PCME terminal I D and Self-Diag- nosis Checker @T page F-7 Check for short circuit in wiring between data link connec- tor terminal TEN and ground as page F-7 Go to next step Try known good PCME page F-144 Check idle air control valve @? page F-106 Gartner Banana