Mazda 626 Station Wagon, Workshop Manual

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TROUBLESHOOTING
STEP INSPECTION RESULTS ACTION
14 Connect NGS tester to DLC.
Turn ignition switch on.
Retrieve any DTC.
Is any DTC displayed?
Yes DTC is displayed:
Go to appropriate DTC test.
If communication error message is displayed on
NGS tester, inspect for following:
• Open circuit between main relay and PCM
terminal 71 or 97
• Open main relay GND circuit
• Main relay is stuck open.
• Open PCM GND circuit (terminal 24, 51, 76,
77 or 103)
• Poor connection of vehicle body GND
No No DTC displayed:
Go to next step.
15 Attempt to start engine at part throttle.
Does engine run smooth at part throttle?
Yes Inspect IAC valve and wiring harness.
No Go to next step.
16
Connect NGS tester to DLC.
Access RPM PID.
Is RPM PID indicating engine speed during
engine cranking?
Yes Go to next step.
No
Inspect for following:
• Open or short circuit in CKP sensor
• Open or short circuit between CKP sensor
and PCM terminal 21 or 22
• 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.
No Replace malfunctioning parts.
18 Measure gap between CKP sensor and teeth of
crankshaft pulley.
Specification
0.5—1.5 mm {0.020—0.059 In}
Is gap within specifications?
Yes Go to next step.
No Adjust CKP sensor.
19 Inspect for cracks on high-tension leads
Is there any crack on high-tension leads? Yes Repair suspected high-tension lead.
No Go to next step.
20 Is strong blue spark visible at each
disconnected high-tension lead while cranking
engine?
Yes Go to next step.
If symptom occurs with A/C on, go to Step 26.
No Inspect for following:
• Ignition coil
• Open or short circuit in ignition coil
• Open circuit in high-tension leads
• Open circuit between ignition coil connector
GND terminal and body ground
• Open circuit between ignition switch and
ignition coil
• Open circuit between ignition coil and PCM
terminal 26 or 52
21
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 next step.
22 Remove and shake PCV valve.
Does PCV valve rattle?
Yes Go to next step.
No Replace PCV valve.
23 Is there any restriction in exhaust system? Yes Inspect exhaust system.
No Go to next step.
FI-111