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Home >> Mazda >> 2006 >> 6 s, 4D Wagon, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (Symptom Troubleshooting [Engine Control System L3)) >> No. 6 Cranks Normally But Will Not Start >> Diagnostic procedure

Diagnostic procedure

WARNING: This page is about a different variant/trim than selected.
DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 Connect WDS or equivalent to DLC-2.
Do any of the following conditions appear?
  • Engine does not completely start.
  • DTC B1681 is displayed.
 Yes Both conditions appear: 
Go to Step 3.
No Either or other condition appears: 
Go to the next step.
2 Does engine stall after approx. 2 s  from when it is started? Yes Go to the next step.
No Immobilizer system is okay.
Go to Step 10.
3 Is coil connector securely connected to coil? Yes Go to the next step.
No Connect coil connector securely.
Return to Step 2.
4 Does security light illuminate? Yes Go to the next step.
No Inspect instrument cluster and wiring harness.
5 Connect WDS equivalent to DLC-2 and retrieve DTC.
Are any of the following DTCs displayed?
DTC 
B1213, B1342, B1600, B1601, B1602, B1681, B2103, B2431 		 Yes Go to appropriate DTC test.
No Go to the next step.
6 Is there continuity between PCM GND terminals 1AZ, 1BB, 1BD, 1BH and GND? Yes Go to the next step.
No Repair or replace wiring harness.
7 Measure voltage between PCM GND terminals 1AZ, 1BB, 1BD, 1BH and coil terminal C.
Is voltage below 1.0 V  ?		 Yes Go to the next step.
No Repair or replace wiring harness.
8 Turn ignition switch to ON position.
Access VPWR PID.
Is VPWR PID normal?
VPWR PID 
Battery voltage 		 Yes Go to the next step.
No Repair or replace wiring harness.
9 Disconnect coil connector.
Turn ignition switch to ON position.
Is there battery voltage at coil connector terminal D?		 Yes Inspect for the following:
  • Open or short circuit between coil terminal A and PCM terminal 1F
  • Open or short circuit between coil terminal B and PCM terminal 1E
No Repair or replace wiring harness between coil connector terminal D and fuse panel.
10 Verify the following:
  • Vacuum connection
  • External fuel shut off or accessory (such as kill switch, alarm)
  • 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
  • Ignition wiring
  • Electrical connections
  • Fuses
  • Smooth operation of throttle valve

Are all items normal?		 Yes Go to the next step.
No Service if necessary.
Repeat Step 10.
11 Connect WDS or equivalent to DLC-2.
Turn ignition switch to ON position (Engine off).
Retrieve any DTCs.
Are there any DTCs displayed?		 Yes DTC is displayed: 
Go to appropriate DTC test.
Communication error message is displayed: 
Inspect for the following:
  • Open circuit between main relay and PCM terminal 1BE or 1AW(1)
  • Open main relay terminal E and PCM terminal 1Q
  • Main relay is stuck open.
  • Open or poor GND circuit (PCM terminal 1AZ, 1BB, 1BD or 1BH)
  • Poor connection of vehicle body GND
No No DTC is displayed: 
Go to the next step.
12 Turn ignition switch to OFF position.
Disconnect TP sensor connector.
Measure voltage at TP sensor connector terminal B with ignition switch to ON position.
Voltage 
4.5-5.5 V 
Is voltage normal?		 Yes Go to the next step.
No Inspect and repair open or short circuit between PCM terminal 2AO and TP sensor terminal B.
13 Turn ignition switch to OFF position.
Disconnect accelerator position sensor connector.
Measure voltage at accelerator position sensor connector VREF terminals with ignition switch to ON position.
Voltage 
4.5-5.5 V 
Is voltage normal?		 Yes Go to the next step.
No Inspect and repair open or short circuit for the following:
  • PCM terminal 1AJ and accelerator position sensor terminal A
  • PCM terminal 1AL and accelerator position sensor terminal D
14 Does engine start with throttle closed? Yes Go to Step 29.
No Go to the next step.
15 Will engine start and run smoothly at part throttle? Yes Inspect electronic throttle control system operation.
(See ELECTRONIC THROTTLE CONTROL SYSTEM INSPECTION ).
No Go to the 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 the next step.
No Inspect for the following:
  • Open or short circuit in CKP sensor
  • Open or short circuit between CKP sensor and PCM terminal 2W or 2AQ
  • Open or short circuit in between CKP sensor and GND
  • Open or short circuit in CKP sensor harnesses

If CKP sensor and harness are okay, go to the next step.
17 Visually inspect CKP sensor and teeth of crankshaft pulley.
Are CKP sensor and teeth of crankshaft pulley normal?		 Yes Go to the next step.
No Replace malfunctioning parts.
18 Inspect ignition coil related harnesses condition (intermittent open or short circuit) for all cylinders.
Are all harnesses condition normal?		 Yes Go to the next step.
No Repair suspected wiring harness.
19 Perform Spark Test.
(See SPARK TEST ).
Is the strong blue spark visible at each cylinder?		 Yes Go to the next step.
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.
No Install spark plugs on original cylinders.
Go to the next step.
21 Remove and shake PCV valve.
Does PCV valve rattle?		 Yes Go to the next step.
No Replace PCV valve.
22 Inspect for restriction in exhaust system. Yes Inspect exhaust system.
No Go to the next step.
23 Install fuel pressure gauge between fuel pipe and fuel distributor.
Short check connector terminal F/P to body GND using a jumper wire.
Turn ignition switch to ON position.
Is fuel line pressure correct when ignition switch is turned on/off five times  ?
(See FUEL LINE PRESSURE INSPECTION ).		 Yes Go to the next step.
No Zero or low: 
Inspect fuel pump relay and fuel pump circuit.
Inspect for clogged fuel line.
If okay, replace fuel pump unit.
High: 
Replace fuel pump unit.
24 Visually inspect for fuel leakage at fuel injector O-ring and fuel line.
Service if necessary.
Is fuel line pressure held after ignition switch is turned off?
(See FUEL LINE PRESSURE INSPECTION ).		 Yes Go to the next step.
No Inspect fuel injector.
If fuel injector is okay, replace fuel pump unit.
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 sticks open mechanically.
Inspect EVAP control system.
No Go to the next step.
26 Is air leakage felt or heard at intake-air system components while racing engine to higher speed? Yes Repair or replace.
No Go to the next step.
27 Inspect engine condition while tapping EGR valve housing.
Is engine condition improved?		 Yes Replace EGR valve.
No Go to the next step.
28 Inspect variable valve timing control system operation.
(See VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION INSPECTION ).
Does variable valve timing control work properly?		 Yes Go to the next step.
No Repair or replace malfunctioning parts.
29 Is engine compression correct? Yes Inspect valve timing.
No Inspect for causes.
30 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, reprogram PCM if later calibration is available. Retest.
(1) California emission regulation applicable ATX model
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