1994 MAZDA MX-5 diagram

Before beginning any service procedure. refer to section T of this manual for air bag system service warnings and audio antitheft system alarm conditions . FUEL AND EMISSION CONTROL SYSTEMS INDEX ............................ F- 2 ......................... OUTLINE F- 5 .............. SYSTEM DIAGRAM F- 5 VACUUM HOSE ROUTING DIAGRAM ...................... F- 6 WIRING DIAGRAM ............... F- 7 SPECIFICATIONS ............... F- 8 COMPONENT DESCRIPTIONS ... F- 9 ....... TROUBLESHOOTING GUIDE F- 11 ENGINE CONTROL OPERATION CHART ........................ F- 11 RELATIONSHIP CHART .......... F- 12 USING THIS SECTION ........... F- 13 DIAGNOSTIC INDEX ............. F- 15 SYMPTOM TROUBLESHOOTING . F- 17 PREPARATION ................... F- 75 ............. BASIC INSPECTION F- 75 .................. ADJUSTMENT F- 76 ON-BOARD DIAGNOSIS SYSTEM . . F- 78 DESCRIPTION .................. F- 78 PREPARATION .................. F- 79 DIAGNOSTIC TROUBLE CODE NUMBER ...................... F- 79 ... SWITCH MONITOR FUNCTION F- 95 INTAKE AIR SYSTEM .............. F- 98 COMPONENTS .................. F- 98 SYSTEM OPERATION ............ F-100 THROTTLE BODY ............... F-101 INTAKE MANIFOLD .............. F-102 ACCELERATOR PEDAL AND CABLE ........................ F-103 IDLE SPEED CONTROL SYSTEM ... F-104 DESCRI PTlON .................. F-104 PREPARATION .................. F-105 BAC VALVE ..................... F-105 IDLE AIR CONTROL VALVE ....... F-106 FUEL SYSTEM .................... F-107 DESCRIPTION .................. F-107 PREPARATION .................. F-108 SYSTEM OPERATION ............ F-109 FUEL TANK ..................... F-111 FUEL FILTER .................... F-113 FUEL PUMP .................... F-114 FUEL PUMP RELAY .............. F-117 PRESSURE REGULATOR ........ F-118 FUEL INJECTOR ................ F-119 PRESSURE REGULATOR CONTROL SYSTEM ......................... F-122 PRC SOLENOID VALVE .......... F-123 EXHAUST GAS RECIRCULATION (EGR) ........................... F-124 PREPARATION .................. F-124 .................. DESCRIPTION F-124 SYSTEM OPERATION F-125 ............ EGR SOLENOID VALVE (VACUUM) F-125 EGR SOLENOID VALVE (VENT) ... F-126 ......... EGR FUNCTION SENSOR F-126 ........... EGR CONTROL VALVE F-127 ................ EXHAUST SYSTEM F-128 .................. COMPONENTS F-128 OUTLINE OF EMISSION CONTROL ......................... SYSTEM F-129 ............. STRUCTURAL VIEW F-129 POSITIVE CRANKCASE VENTILATION ................... (PCV) SYSTEM F-130 ' DESCRIPTION .................. F-I ..................... PCV VALVE F-1 ..... FUEL EVAPORATIVE SYSTEM F- .................. DESCRIPTION F- ....... PURGE SOLENOID VALVE F- ........ TWO-WAY CHECK VALVE F- ...... THREE-WAY CHECK VALVE F- ............. FUEL VAPOR VALVE F- .......... CHARCOAL CANISTER F- CATALYTIC CONVERTER SYSTEM . F- .................. DESCRIPTION F- .......... THREE-WAY CATALYST F- AIC CUT-OFF CONTROL SYSTEM . . F- .................. DESCRIPTION F- ........... SYSTEM INSPECTION F- ...................... A/c RELAY F-1 36 ..... DECHOKE CONTROL SYSTEM F-137 .................. DESCRIPTION F-137 ......... COOLANT FAN CONTROL F-138 ....................... OUTLINE F-138 .................. COOLANT FAN F-139 ............... CONDENSER FAN F-139 ........... SYSTEM INSPECTION F-140 ........... COOLANT FAN RELAY F-140 ........ CONDENSER FAN RELAY F-140 ............... CONTROL SYSTEM F-141 .................. PREPARATION F-141 ............. STRUCTURAL VIEW F-142 POWERTRAIN CONTROL MODULE .............. (ENGINE) (PCME) F-143 ........ MASS AIRFLOW SENSOR F-152 CRANKSHAFT POSITION SENSOR F-153 ENGINE COOLANT TEMPERATURE ...................... SENSOR F-154 THROTTLE POSITION SENSOR . . F-154 HEATED OXYGEN SENSOR ...... F-156 MAIN RELAY .................... F-157 ............... CLUTCH SWITCH F-157 NEUTRAL SWITCH .............. F-157 STEERING PRESSURE SENSOR . F-158 45UOFX-001 Gartner Banana

OUTLINE VACUUM HOSE ROUTING DIAGRAM Gartner Banana

OUTLINE WIRING DIAGRAM 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

ON-BOARD DIAGNOSIS SYSTEM F Circuit Diagram TO IGNITION SWITCH TO BATTERY MAIN RELAY :AF*, CRANKSHAFT POSITION SENSOR Gartner Banana

F ON-BOARD DIAGNOSIS SYSTEM CODE No. 15 (HEATED OXYGEN SENSOR: INACTIVATION) 111 Are there any poor connections in heated oxygen sensor circuit? Note a If Code Nos.15 and 17 are both present, first perform the checking procedure for Code No.17 STEP 1 INSPECTION I ACTION 2 3 Circuit Diagram I Yes No 4 5 ENGINE COOLANT MASS AIRFLOW TEMPERATURE SENSOR SENSOR ~ Repair or replace connector Go to next steD Is heated oxygen sensor output voltage OK? page F-155 Is there continuity between heated oxygen sensor and PCME terminal 2N? THROTTLE POSITION SENSOR 35UOFX-065 Is PCME terminal 2N voltage OK? Is sensitivity of heated oxygen sensor OK? * page F-156 PCME Yes No Yes No Go to next step Replace heated oxygen sensor r@ page F-156 Go to next step Check for open circuit in wiring from heated oxygen sen- sor to PCME Yes No Yes No Go to next step Check for short circuit in wiring from heated oxygen sen- sor to PCME Replace PCME aPi. page F-143 Replace heated oxygen sensor r@ page F-156 Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM F CODE No. 16 (EGR FUNCTION SENSOR) 1 ACTION INSPECTION Does EGR function sensor circuit have a poor con- nection? Is EGR control valve OK? page F-125 Is resistance of EGR function sensor OK? Resistance: (A) o (6) Approx. 2.7 kR (A) o (C) 0.5-2.7 kS2 (B) i+ (C) 0.1-2.4 kR Is there continuity between EGR function sensor and PCME? I EGR function sensor I PCME I Is there 4.5-5.5V at C terminal of EGR function sensor connector? page F-124 Is PCME terminal 2J voltage OK? page F-146 Circuit Diagram Yes No Yes I No I Replace EGR control valve Repair or replace connector Go to next step Go to next step No Yes Replace EGR control valve Go to next step Yes Replace PCME No Check for open circuit in wiring from EGR function sensor to PCME Yes No EGR FUNCTION SENSOR Go to next step Check for short circuit in wiring from EGR function sensor terminal C to PCME Yes No Replace PCME Short circuit in wiring harness EGR function sensor termi- nal C to PCME 39UOFX-106 Gartner Banana

F ON-BOARD DIAGNOSIS SYSTEM CODE No. 17 (HEATED OXYGEN SENSOR: INVERSION) I Circuit Diagram INSPECTION Warm up engine and run it at 2,500-3,000 rpm for 3 min. HEATED OXYGEN SENSOR ACTION Does monitor lamp of Self-Diagnosis Checker illu- minate at idle? Are spark plugs clean? Is heated oxygen sensor voltage OK? * page F-156 Is same Code No. present after performing after repair procedure? ESI= page F-90 Is there continuity between heated oxygen sensor and PCME terminal 2N? Is PCME terminal 2N voltage OK? * page F-146 PCME Yes No Yes No Yes No Yes No Yes No Yes No Go to next step Check for air leak in vacuum hoses or emission compo- nents Check for contaminated heated oxygen sensor Check for insufficient fuel injection Go to next step Clean or replace spark plugs Go to next step Replace heated oxygen sensor page F-156 Go to next step Check for short circuit in wiring from heated oxygen sen- sor to PCME terminal 2N Go to next step Check for open circuit in wiring from heated oxygen sen- sor to PCME Replace PCME page F-143 Check for short circuit in wiring from heated oxygen sen- sor to PCME Gartner Banana