lock MAZDA MX-5 1994 Repair Manual

Neutral swltch (MT) 7 PCV valve Powertrain control mod- ule (engine) (PCME) Purge solenoid valve Resonance chamber Steering pressure sen- Stoplight swltch I Throttle posltion sensor r [Two-way check valve Function jetects amount of intake air; sends signal to powertrain :ontrol module (engine) Li~ht illuminates when input device malfunctions - Light flashes to indicate trouble code number of input and output devices Detects in-gear condition; sends signal to powertrain :ontrol module (engine) - Controls blow by aas amount introduced into engine Detects the followlng: 1. A/C operation 2. Airlfuel ratio (Oxygen concentration) 3. Barometric absolute pressure 4. Braking signal 5. Cranking signal 6. EIL operation 7. Engine coolant temperature 8. Engine speed 9. In-gear condition 10. lntake air amount 11, lntake air temperature 12. No.1 piston TDC 13. PIS operation 14. Initial set signal 15. Throttle valve opening angle Controls operatlon of the followlng: 1. AIC (Cut off) 2. Fail-safe function 3. Fuel injection system 4. ldle speed control 5. Ignition timing control system 6. Monitor function 7. Purge control system 8. Lockup control svstem Controls vacuum to pressure regulator -- Adjusts fuel pressure supplied to fuel injectors Controls evaporative fumes from canister to intake man- ifold -- lm~roves mid-ranae torque characteristics -. Detects PIS operation; sends signal to powertrain con- trol module (engine) -- Detects braking operation (deceleration); sends signal to powertrain control module (engine) Reduces HC, CO, and NOx by chemical reaction Controls pressurein fuel tank Controls intake air quantity Detects position of the throttle valve closed throttle posi- tion; sends signal to powertrain control module (engine) Detects the throttle valve opening at a preset angle; sends si~nal to powertrain control module (engine) controls pressure in fuel tank Remark lntake air temperature sensor and fuel pump switch included Use Vref (5 volt) as power source ' Data link connector terminal TEN ' Data link connector terminal TEN Switch ON when in neutral 1, Air conditioning sesnor 2. Heated oxygen sensor 3. Barometric absolute pressure sensor 4. Stoplight switch 5. Ignition switch (START position) 6. Coolant fan relay Light and turn relay Blower switch 7. Engine coolant temperature sensor 8. Crankshaft position sensor (SGT-signal) 9. Neutral and dutch switches (MT) Parklneutral switch (AT) 10. Mass airflow sensor 11, lntake air temperature sensor 12. Crankshaft position sensor (SGC-signal) 13. Steering pressure switch 14. Data link connector 15. Throttle position sensor 1. NC relay 2. Self-diagnosis checker and MIL 3. Fuel injector 4. IAC valve 5. Igniter 6. Monitor lamp (Self-diagnosis checker) 7. Purge solenoid valve 8. Powertrain control module (transmission) (AT) D Controlled by duty signal from powertrain control module (engine) D PIS: ON when steering wheel turned Monolith type D Integrated throttle position sensor, Idle air control valve, and dashpol Gartner Banana

F TROUBLESHOOTING GUIDE Troubleshooting chart F TROUBLESHOOTING GUIDE 7 I - page F-79 CRANKS NORMALLY BUT HARD TO START - AFTER WARM-UP 1 Check if PCME terminal voltaoes are OK Check If '00" is displayed on Sell-Diagnosis Check- er wilh lonillon switch ON I (2D* 2R and *) page 6145 'SCRIPTION Enginecranks 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 TROUBLESHOOTING HINTS] D AidFuel mixture too rich @ Vapor lock Fuel injection control malfunction . Fuel pressure not held In fuel line after engine stop Fuel injector fuel leakage . High RVP (winter) fuel used In warm weather ITEP I INSPECTlON Yes "88" flashes I Check PCME terminal I E ~Itg " p8gO F-I45 1 ACVON Go to next slep No Speclflcatlon: Baltery porltlve voltage (Ignition rwltch 1 ON) Diagnostic Trouble Code No. dlrplayed Check lor cause (Refer lo specified check sequence) a page F-81 If OK, replace PCME rr F-143 I:, if not OK, check wiring between PCME and Sell-Diagno- sis Checker LQ page M I No Check for cause (Refer to 'Check Pdnt for Each Terml- nal') page F-1 I -- ~ Yes Go lo next step I p- / Yes DESCRIPTION: Further describes the symptom. Confirm that the chart addresses the actual symptom before beginning troubleshooting. Go to next slep TROUBLESHOOTING HINTS: This describes the possible point of malfunction. STEP: This shows the order of troubleshooting. Proceed with troubleshooting as indicated. INSPECTION: This describes an inspection to quickly determine the malfunction of parts. If a detailed procedure is nec- essary to perform the INSPECTION, refer to the page shown by the "UW' mark. ACTION: This recommends the appropriate action to take as a result (YesINo) of the INSPECTION. How to per- form the action is described on the reference page shown by the "=" mark. Gartner Banana

TROUBLESHOOTING GUIDE 7 CRANKS NORMALLY BUT WILL NOT START (PARTIAL COMBUSTION) -AFTER WARM-UP I ~ngine starts normally when cold TROUBLESHOOTING HINTS] D AirIFuel mixture too rich O Vapor lock Fuel pressure not held in fuel line after engine stops High RVP (winter) fuel used in warm weather 'ESCRIPTIoN Fuel injection control malfunction (Correction for coolant temperature) Fuel injector fuel leakage I INSPECTION Engine cranks at normal speed but shows partial combustion and will not continue to run after running and hol soaked Battery in normal condition :heck if "00" is displayed on Self-Diagnosis Checker with ignition switch ON @S page F-79 :heck if PCME terminal voltages are OK :2D and 20) page F-136 sonnect data link connector terminals F/P and GND ~ith jumper wire and check for correct fuel line pres- sure with ignition switch ON page F-110 Fuel Line pressure: 26-14 kPa {2.7-3.2 kgflcm2, 38-46 psi) GND F~P INSTALL CLAPS ' Yes No - 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 page F-145 Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME page F-143 0 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 Terminal") page F-148 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 fuel line and filter for clogging If not clogged, check fuel pump maximum pressure page F-115 - High pressure Check if fuel return hose is clogged or restricted a If OK, replace pressure regulator page F-119 6 If not OK, repair or replace Gartner Banana

F TROUBLESHOOTING GUIDE INSPECTION With condition of step 3, check if fuel line pressure is held after ignition switch is turned OFF page F-109 Fuel line pressure: More than 147 kPa (1.5 kgf/cm2, 21 psi) for 5 min. PRESSURE MINIMUM IGNITION 5 MIN. TIME SWITCH OFF Check if fuel line pressure is held after ignition switch is turned OFF and blocking outlet of pressure regula- tor page F-118 Fuel line pressure: More than 147 kPa {I .5 kgf/cm2, 21 psi) for 5 min. Try known good PCME and check if condition page F-144 - Yes - No - Yes - No - Yes ACTION 30 to Step 6 30 to Step 5 3eplace pressure regulator EF page F-119 :heck fuel pump hold pressure page F-114 3 If OK, check fuel injector for fuel leakage page F-120 3 If not OK, replace fuel pump page F-115 qeplace PCME 2hange fuel to another brand 35UOFX-O' 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

ENGINE TUNE-UP ENGINE TUNE-UP PREPARATION L" SST r I I 16EOF2-012 BASIC INSPECTION Engine Oil 1. Remove the dipstick and check the engine oil level and condition. 2. Add or change oil as necessary. 49 B019 9AO System Selector Coolant (engine cold) For inspection of ignition timing and idle speed Warning Removing the radiator cap or the coolant drain plug while the engine is running, or when the en- gine and radiator are hot is dangerous. Scalding coolant and steam may shoot out and cause seri- ous injury. It may also damage the engine and cooling system. Turn off the engine and wait until it is cool. Even then, be very careful when remov- ing the cap. Wrap a thick cloth around it and slow- ly turn it counterclockwise to the first stop. Step back while the pressure escapes. When you're sure all the pressure is gone, press down on the cap-still using a cloth-turn it, and remove it. 1. Verify that the coolant level is near the radiator filler neck. 2. Verify that the coolant level on the coolant dipstick is be- tween the F and L marks. 3. Add coolant if necessary. Battery Removing the label on the top of the battery or removing the vent caps will void the battery's warranty. 1. Clean any corrosion on the clamps or battery posts. 2. Verify that the battery top is clean. If necessary, clean with baking soda and water. 3. Verify that cables are in good condition and not frayed or corroded. Repair or replace if necessary. 4. Verify that cable clamps are tight. Note Because this is a maintenance free battery, it is not necessary to check the fluid level. Gartner Banana

ENGINE TUNE-UP 8. If the marks are not aligned, remove the ignition coil bracket and push the ignition coil aside for easy access and then loosen the crankshaft position sensor lock bolts, and turn the crankshaft position sensor to make the adjustment. 9. Tighten the distributor lock bolts to the specified torque. Tightening torque: 19-25 N-m (1.9-2.6 kgfem, 14--18 ftqlbf) 10. After adjusting the ignition timing, disconnect the jumper wire or SST from the data link connector. 11. Increase the engine speed and verify that the ignition timing advances. 12. Verify that the ignition timing is within the specification. Ignition timing: BTDC 6-18' ldle Speed 1. Perform Preparation. (Refer to page F-76.) 2. Set switch A to position 1. 3. Set test switch to SELF TEST. 4. With the coolant fan off, verify that the idle speed is within specification. ldle speed (Neutral): 800-900(850 + 50) rpm [MT] (P range): 750--850(800 -c 50) rpm [AT] 5. If not within the specification, adjust the idle by turning the air adjusting screw. 6. Disconnect the SST. Gartner Banana

F FUEL SYSTEM PRESSURE REGULATOR Inspection Fuel line pressure d Warning Fuel line spills and leaks can be dangerous. Fuel can ignite and cause serious injuries or death and can damage the vehicle. Fuel can also irritate skin and eyes. To prevent this from happening, release the fuel pressure according to "Fuel Line Safety Procedures" on page F-108. 1. Disconnect the negative battery terminal. 2. Connect a fuel pressure gauge between the fuel main pipe and the fuel main hose. (Install clamps as shown.) 3. Connect the negative battery terminal. 4. Start the engine and run it at idle. 5. Measure the fuel line pressure. Fuel line pressure: 21 6-264 kPa (2.2-2.7 kgf/cm2, 32-38 psi) Hold pressure Perform this inspection if the fuel pressure hold inspec- tion is not as specified. (Refer to page F-104.) Warning Fuel line spills and leaks can be dangerous. Fuel ,-, can ignite and cause serious injuries or death and can damage the vehicle. Fuel can also irritate skin and eyes. To prevent this from happening, release the fuel pressure according to "Fuel Line Safety Procedures" on page F-108. 1. Disconnect the negative battery terminal. 2. Install a fuel pressure gauge between the fuel pipe and the fuel main hose. (Install clamps as shown.) 3. Connect the negative battery terminal. 4. Connect data link connector terminals F/P and GND with a jumper wire. 5. Turn the ignition switch ON for 10 sec. to operate the fuel pump. 6. Turn the ignition switch OFF and disconnect the jumper wire. 7. Block the outlet of the pressure regulator. 8. Observe the fuel pressure for 5 min. Fuel pressure: More than 147 kPa {I .5 kgf/cm2, 21 psi) 9. If pressure is as specified, replace the pressure regula- tor. Gartner Banana

F POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM DESCRIPTION The PCV valve is operated by the intake manifold vacuum. 4 When the engine is running at idle the PCV valve is opened slightly and a small amount of blow by gas is drawn into the intake manifold to be burned. At higher engine speeds the PCV valve is opened further, allowing a larger amount of blow by gas to be drawn into the intake manifold. VENTILATION I PCV VALVE Inspection 1. Warm up the engine to the normal operating tempera- ture and run it at idle. 2. Disconnect the PCV valve together with the ventilation hose from the cylinder head cover. 3. Block the PCV valve opening. 4. Verify that vacuum is felt. 5. Remove the PCV valve. 6. Blow through the valve from port A and verify that air comes out of port B. 7. Blow through the valve from port B and verify that no air comes out of port A. 8. Replace the PCV valve if necessary. 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