Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.

CRANKS NORMALLY BUT WILL NOT START - DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	NOTE: Following test should be performed on vehicles with immobilizer system. Go to Step 12 for vehicles without immobilizer system. Connect WDS or equivalent to DLC-2. Do following conditions appear? Engine is not completely started. DTC P1624 is displayed.	Yes	Both conditions appear: Go to Step 4.
1		No	Either or other condition appear: Go to next step.
2	Does engine stall after approx. 2 seconds since engine is started?	Yes	Go to next step.
2		No	Immobilizer system is okay. Go to Step 12.
3	Is immobilizer unit connector securely connected to immobilizer unit?	Yes	Go to next step.
3		No	Connect immobilizer unit connector securely. Return to Step 2.
4	Does immobilizer indicator light flash and indicate following immobilizer system DTC? DTC 01,02,03,11,21	Yes	Go to "ON-BOARD DIAGNOSTIC FUNCTION" of immobilizer system.
4		No	Go to next step.
5	Does immobilizer indicator light illuminate?	Yes	Go to Step 8.
5	Does immobilizer indicator light illuminate?	No	Go to next step.
6	Does immobilizer indicator light flash and indicate following immobilizer system DTC after more than 135 seconds after ignition key is turned to ON (Engine OFF)? DTC 24, 30	Yes	Go to "ON-BOARD DIAGNOSTIC FUNCTION" of immobilizer system.
6		No	Go to next step.
7	Turn ignition key to OFF. Disconnect immobilizer unit connector. Connect jumper wire between immobilizer unit connector terminal M and GND. Turn ignition switch to ON (Engine OFF). Does immobilizer indicator light illuminate?	Yes	Reconnect immobilizer unit connector. Go to next step.
7		No	Inspect for open circuit between immobilizer unit connector terminal M and instrument cluster. If okay, inspect immobilizer indicator light bulb. Repair or replace if necessary. Reconnect immobilizer unit connector, then return to Step 4.
8	Connect WDS or equivalent to DLC and retrieve DTC. Is following DTC displayed? DTC P1602, P1603, P1604, P1621, P1622, P1624	Yes	Go to appropriate DTC test.
8		No	Go to next step.
9	Is there continuity between PCM ground terminals 6/22/23/25/100 and GND?	Yes	Go to next step.
9		No	Repair or replace wiring harness.
10	Turn ignition key to ON (Engine OFF). Inspect voltage between PCM terminals 34 and 60. Is voltage above 11.5 V?	Yes	Go to next step.
10		No	Repair or replace wiring harness.
11	Disconnect immobilizer unit connector. Turn ignition key to ON (Engine OFF). Is there battery voltage at immobilizer unit connector terminal J?	Yes	Inspect for open circuit between PCM connector terminal 64 and immobilizer unit connector terminal A.
11		No	Repair or replace wiring harness between immobilizer unit connector terminal J and fuse panel.
12	Verify following: Vacuum connection External fuel shut off or accessory (kill switch, alarm etc.) Fuel quality: proper octane, contamination, winter/summer blend No air leakage from intake-air system Proper sealing of intake manifold and components attached to intake manifold: EGR valve, I AC valve Ignition wiring Electrical connections Fuses Smooth operation of throttle valve Are all items okay?	Yes	Go to next step.
12		No	Service as necessary. Repeat Step 12.
13	Connect WDS or equivalent to DLC-2. Turn ignition key to ON (Engine OFF). Retrieve any DTCs. Is "PASSED" displayed?	Yes	No DTC is displayed: Go to next step.
13		No	DTC is displayed: Go to appropriate DTC test. Communication error message is displayed: Inspect for following: Open circuit between main relay and PCM terminal 34,60 Open main relay GND circuit Main relay is stuck open. Open or poor GND circuit (PCM terminal 6, 22, 23, 25 or 100) Poor connection of vehicle body GND
14	Turn ignition key to ON (Engine OFF). Disconnect TP sensor connector Measure voltage at TP sensor connector VREF terminal with ignition key at ON. Voltage 4.5-5.5 V Is voltage okay?	Yes	Go to next step.
14		No	Go to troubleshooting in NO.29 CONSTANT VOLTAGE . (See NO.29 CONSTANT VOLTAGE .)
15	Will engine start and run smoothly at part throttle?	Yes	Inspect IAC valve and wiring harness.
15	Will engine start and run smoothly at part throttle?	No	Go to next step.
16	Connect WDS or equivalent to DLC-2. Access RPM PID. Is RPM PID indicating engine speed when cranking engine?	Yes	Go to next step.
16		No	Inspect for following: Open or short circuit in CKP sensor Open or short circuit between CKP sensor and PCM terminal 1 or 27 Open or short circuit in CKP sensor harnesses If CKP sensor and harness are okay, go to next step.
17	Visually inspect CKP sensor and teeth of crankshaft pulley. Are CKP sensor and teeth of crankshaft pulley okay?	Yes	Go to next step.
17		No	Replace malfunctioning part.
18	Inspect ignition coil related harnesses condition (intermittent open or short circuit) for all cylinders. Are all harnesses condition okay?	Yes	Go to next step.
18		No	Repair suspected wiring harness.
19	Perform spark test. (See SPARK TEST .) Is strong blue spark visible at each cylinder?	Yes	Go to next step.
19		No	Repair or replace malfunctioning part according to spark test results.
20	Inspect spark plug conditions. Is spark plug wet, covered with carbon or grayish white?	Yes	Spark plug is wet or covered with carbon: Inspect for fuel leakage from injector. Spark plug is grayish white: Inspect for clogged fuel injector.
20		No	Install spark plugs on original cylinders. Go to next step.
21	Remove and shake PCV valve. Does PCV valve rattle?	Yes	Go to next step.
21	Remove and shake PCV valve. Does PCV valve rattle?	No	Replace PCV valve.
22	Inspect for restriction in the exhaust system. Is there any restriction?	Yes	Inspect exhaust system.
22		No	Go to next step.
23	Install fuel pressure gauge between pulsation damper and fuel distributor. Connect jumper wire between F/P terminal at DLC in engine compartment and GND. Turn ignition key to ON (Engine OFF). Is fuel line pressure correct when ignition switch is cycled ON/OFF five times? Fuel line pressure 420-460 kPa {4.3-4.6 kgf/cm2, 61-66 psi}	Yes	Go to next step.
23		No	Zero or low: Inspect fuel pump circuit. Inspect for open fuel pump relief valve. Inspect for fuel leakage inside pressure regulator. Inspect for clogged main fuel line. High: Inspect pressure regulator for high pressure cause. Inspect for clogged fuel return line.
24	Visually inspect for fuel leakage at fuel injector O-ring and fuel line. Service as necessary. Is fuel line pressure held after ignition key is turned to OFF?	Yes	Go to next step.
24		No	Inspect pressure regulator diaphragm condition. If condition is okay, inspect fuel injector. If condition is not okay/replace pressure regulator.
25	Disconnect vacuum hose between purge solenoid valve and intake manifold from purge solenoid valve side. Plug opening end of vacuum hose. Attempt to start engine. Is starting condition improved?	Yes	Inspect if purge solenoid valve is stuck open mechanically. Inspect EVAP control system.
25		No	Go to next step.
26	Is air leakage felt or heard at intake-air system components while racing engine to higher speed?	Yes	Repair or replace.
26		No	Go to next step.
27	Inspect engine condition while tapping EGR valve housing. Does engine condition improve?	Yes	Replace EGR valve.
27		No	Go to next step.
28	Is engine compression correct? (See COMPRESSION INSPECTION .)	Yes	Inspect valve timing.
28		No	Inspect for causes.
29	Verify test results. If okay, return to diagnostic index to service any additional symptoms. If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis. If vehicle is repaired, troubleshooting completed. If vehicle is not repaired or additional diagnostic information is not available, replace or reprogram PCM.