Mazda MX-6 1998, Workshop Manual

Page: 164 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
STEP INSPECTION
ACTION
7
Turn ignition switch off.
Disconnect immobilizer unit connector.
Connect jum per between immobilizer unit
connector terminal M and ground.
Turn ignition switch ON.
Does security light illuminate?
Yes
Reconnect immobilizer unit connector.
Go to next step.
No
Inspection open circuit between immobilizer unit connector
terminal M and instrument cluster.
If okay, inspect security light bulb.
Repair or replace if necessary.
Reconnect immobilizer unit connector.
Then return to step 4.
8
Connect NGS tester to DLC and retrieve DTC.
Is following DTC displayed?
DTC: P1602, P1603, P1604, P1621, P1622,
P1624
Yes Go to appropriate DTC test.
No Go to next step.
9 Is there continuity between PCM ground
terminal 23, 24, 51, 76, 77, 103 and ground?
Yes
Go to next step.
No Repair or replace wiring harness.
1 0
Turn ignition switch ON.
Access VPWR PID.
Is VPWR PID okay?
VPWR PID: Battery voltage
Yes Go to next step.
No Repair or replace wiring harness.
1 1
Disconnect immobilizer unit connector.
Turn ignition switch ON.
Is there battery voltage at immobilizer unit
connector terminal J?
Yes Check for open circuit between PCM connector terminal 5
and immobilizer unit connector terminal A.
No Repair or replace wiring harness between immobilizer unit
connector terminal J and fuse panel.
1 2
Verify following:
• External fuel shut off or accessory (ignition
switch, alarm etc.).
• Fuel quality: such as proper octane,
contamination, winter/summer blend.
• No air leaks 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.
Are all items okay?
Yes Go to next step.
No Service as necessary and repeat step 12.
13 Retrieve and record any continuous memory
and KOEO DTCs.
Are there any DTCs displayed?
Yes Go to appropriate DTC test.
No If communication error message is displayed on NGS
tester, check following:
• Open circuit between main relay and PCM using
breakout box.
• Open main relay ground circuit.
• Main relay stuck open.
• Open PCM ground circuit.
• Poor connection of vehicle body ground.
If NGS tester works and no DTCs are displayed, go to
next step.
14 Does engine start with throttle closed? Yes Go to step 33.
No Go to next step.
15 Will engine start and run smoothly at part
throttle? Yes Check 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 when
cranking the engine?
Yes
Go to next step.
No Check following:
• Open or short circuit in CKP sensor.
• Open or short circuit between CKP sensor and PCM.
• Open or short circuit between CKP sensor harnesses.
If CKP sensor and harness okay, go to next step.
17 Visually inspect crankshaft position (CKP)
sensor and teeth of crankshaft pulley.
Is CKP sensor and teeth of crankshaft pulley
okay?
Yes Go to next step.
No
Replace malfunctioning part.
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