Mazda MX-6 1998, Workshop Manual

Page: 325 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION
ACTION
3
CHECK EVAP SYSTEM FOR STUCK OPEN
VALVE
• Key off.
• Disconnect hoses at purge solenoid valve.
• Connect vacuum pump to charcoal canister
at purge solenoid valve.
• Apply -5 .3 kPa {-4 0 6 mmHg, -1 6 inHg) of
vacuum to purge solenoid valve.
• Does p urge s o le n o id valve hold vacuum
fo r 20 se co n d s?
Yes Go to next step.
No REPLACE purge solenoid valve.
RECONNECT all components.
RESET PCM to completely clear DTCs.
tr After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
4 CHECK IAC VALVE ASSEMBLY FOR
Yes Go to next step.
PROPER FUNCTION
• Key on, engine running.
• Bring engine to normal operating
temperature.
• Transaxle in Park or Neutral.
• Disconnect IAC valve assembly connector.
• Does RPM d ro p o r engine sta ll?
No
INSPECT throttle body for damage or defect.
SERVICE as necessary.
If okay, REPLACE IAC valve assembly.
RESET PCM to completely clear DTCs.
tr After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
5 CHECK IAC VALVE CIRCUIT FOR SHORT
TO GND
• Key off.
• Disconnect NGS tester from DLC.
• IAC valve disconnected.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion, loose wires,
etc. Service as necessary.
• Measure resistance between Test Pin 83
and Test Pins 51 and 103 at breakout box.
• Is each re sista n ce greater th a n 10,000
o h m s?
Yes
For Fast Idle Symptom currently present:
REPLACE PCM.
REMOVE breakout box.
RECONNECT all components.
RERUN OBD Test.
A ll others:
RECONNECT all components.
Go to next step.
No SERVICE short circuit.
RECONNECT all components.
RERUN OBD Test.
6 CHECK IAC SYSTEM FOR INTERMITTENT
OPEN OR SHORT
• NGS tester connected.
• Key on, engine running.
• Access IAC and RPM PIDs.
• With engine at normal operating
temperature and all accessories off and at
idle, IAC duty cycle should between 20%
and 40%.
• Observe IAC and RPM PIDs for indication
of fault while performing following at idle:
• Lightly tap on IAC valve assembly and
wiggle harness connector to simulate
road shock
• Grasp vehicle harness closest to IAC
valve assembly. Shake and bend small
section of harness from IAC valve to
dash panel and from dash panel to PCM
• Do IAC or RPM PIDs suddenly change in
valve indicating fault?
Yes
ISOLATE fault and SERVICE as necessary.
RECONNECT all components.
RESET PCM to completely clear DTCs.
tr
After Repair Procedure
COMPLETE OBD II Drive Mode.
No
For idle quality, starting, or stalling symptoms
currently present:
REPLACE IAC valve assembly.
RECONNECT all components.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
Others:
Unable to duplicate and/or identify fault at this time.
Intermittent poor connection or component malfunction
(REPAIR or REPLACE as necessary).
Go to ENGINE SYMPTOM TROUBLESHOOTING No.27.
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