Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION ACTION
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.
10 Turn ignition switch ON.
Access VPWR PID.
Is VPWR PID okay?
VPWR PID: Battery positive voltage
Yes Go to next step.
No Repair or replace wiring harness.
11 Disconnect immobilizer unit connector.
Turn ignition switch ON.
Is there battery positive 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.
12
Verify following:
• Vacuum connection.
• Air cleaner element.
• No air leaks from intake air system.
• No restriction of intake air system.
• Proper sealing of intake manifold and
components attached to intake manifold
(i.e., EGR valve, IAC valve.)
• Ignition wiring.
• Fuel quality; such as proper octane,
contamination, winter/summer blend.
• Electrical connections.
Are all items okay?
Yes Go to next step.
No Service as necessary and repeat step 12.
13 Does vehicle now stall at idle in park/neutral
with all accessories off?
Yes Vehicle stalls now. Go to step 15.
No Go to next step.
14 Retrieve and record any continuous memory,
KOEO and KOER DTCs. If engine stalls,
retrieve continuos memory and KOEO DTCs.
Are there any DTCs displayed?
Yes DTC displayed.
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 to open.
• Open PCM ground circuit.
• Poor connection of vehicle body ground.
If NGS tester works and no DTCs are displayed, go to
step 16.
15
Retrieve and record any continuous memory
and key on engine off diagnostic trouble code.
Is any diagnostic trouble code displayed?
Yes Diagnostic trouble code displayed.
Go to diagnostic trouble code.
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 to open.
• Open PCM ground circuit.
• Poor connection of vehicle body ground.
If NGS tester works and no DTCs are displayed, go to
next step.
16 Attempt to start engine at part throttle.
Does engine run smooth at part throttle?
Yes Check IAC valve and wiring harness.
No Go to next step.
17 Connect NGS tester to DLC.
Access RPM PID.
Is RPM PID indicating engine speed during
cranking of 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 and
harness.
If CKP sensor and harness okay, go to next step.
18
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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