Mazda MX-6 1998, Workshop Manual, Page: 110 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
STEP
INSPECTION ACTION
6 CHECK IAC VALVE SIGNAL CIRCUIT
CONTINUITY
• Key off.
• IAC valve disconnected.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion, loose wires,
etc. Service as necessary.
• Install breakout box. Leave PCM
disconnected.
• Measure resistance between appropriate
Test Pin at breakout box and IAC circuit at
IAC valve connector.
• IAC valve terminal A and Test Pin 20
• IAC valve terminal B and Test Pin 83
• Is resistance less than 5.0 ohms?
Yes Go to next step.
No SERVICE open circuit.
REMOVE breakout box.
RECONNECT all components.
RERUN OBD Test.
7 CHECK IAC VALVE CIRCUIT FOR SHORT
TO POWER CIRCUIT
• Key off.
• Breakout box installed. PCM disconnected.
• IAC valve disconnected.
• Key on, engine off.
• Measure voltage between appropriate Test
Pin at breakout box and chassis ground.
• IAC valve terminal A=Test Pin 20
• IAC valve terminal B=Test Pin 83
• Is voltage less than 1.0 volt?
Yes Go to next step.
No
SERVICE short circuit.
REMOVE breakout box.
RECONNECT all components.
RERUN OBD Test.
8 CHECK IAC VALVE SIGNAL CIRCUIT FOR
SHORT TO GROUND
• Key off.
• Breakout box installed. PCM disconnected.
• IAC valve disconnected.
• Measure resistance between appropriate
Test Pin and Test Pins 51 and 103 (PWR
GND) at breakout box.
• IAC valve terminal A=Test Pin 20
• IAC valve terminal B=Test Pin 83
• Is each resistance greater than 10,000
ohms?
Yes
Go to next step.
No SERVICE short circuit.
RECONNECT all components.
RERUN OBD Test.
9 CHECK IAC VALVE SIGNAL FROM PCM
• Key off.
• Breakout box installed.
• Reconnect PCM to breakout box.
• Reconnect IAC valve.
• Connect DVOM between Test Pin 83 and
Test Pin 51 at breakout box.
• Start engine.
• Slowly increase rpm to 3,000 rpm.
•
Is voltage between 3.0 and 11.5 volts?
Yes
For Continuous Memory DTCs P1504 and P1507.
Go to next step.
INSPECT throttle body for damage, SERVICE as
necessary.
If okay, REPLACE IAC valve assembly.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No REPLACE PCM.
REMOVE breakout box.
RECONNECT all components.
RERUN OBD Test.
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