Mazda MX-6 1998, Workshop Manual

Page: 244 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
STEP
INSPECTION ACTION
6
CHECK RESISTANCE OF HEATED OXYGEN
SENSOR AND HEATED OXYGEN SENSOR
GROUND CIRCUIT
• Key off.
• Disconnect PCM. Inspect both ends of
connector for bent or pushed out pins,
corrosion or other damage. Service as
necessary.
• Install breakout box. Leave PCM
disconnected.
• Disconnected suspected heated oxygen
sensor from harness. Inspect both ends of
connector for damaged or pushed out pins,
moisture, corrosion, loose pins. Service as
required.
• Measure resistance between suspected
heated oxygen sensor signal Test Pin at
breakout box and heated oxygen sensor
vehicle harness connector. Use pin
assignment below and record reading:
• H 02S (Front RH)=Test Pin 60
• H 02S (Front LH)=Test Pin 87
• H 02S ground=Test Pin 91
• Is resistance reading less than 5.0
ohms?
Yes
Go to next step.
No SERVICE open circuit.
REMOVE breakout box.
RECONNECT PCM and heated oxygen sensor.
RESET PCM to completely clear DTCs.
tr After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
7 CHECK HEATED OXYGEN SENSOR
CIRCUIT WIRING HARNESS FOR SHORT
TO GROUND
• Key off.
• Breakout box installed. PCM disconnected.
• Heated oxygen sensor disconnected.
• Measure resistance between suspected
heated oxygen sensor signal Test Pin and
Test Pins 23, 24, 51, 76, 77, 103 and 91 at
breakout box.
• Is each resistance greater than 10,000
ohms?
Yes Go to next step.
No SERVICE short circuit.
REMOVE breakout box.
RECONNECT PCM and heated oxygen sensor.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
8 CHECK HEATED OXYGEN SENSOR FOR
SHORT TO GROUND OR PCM GROUND
(BETWEEN PCM AND H 02S GROUND
CIRCUIT)
• Key off.
• Breakout box installed. PCM disconnected.
• Reconnect heated oxygen sensor.
• Measure resistance between ground circuit
and PCM ground Test Pins and heated
oxygen sensor signal Test Pin at breakout
box:
• H 02S (Front RH) signal=Test Pin 60
• H 02S (Front LH) signal=Test Pin 87
• Ground=Test Pin 24 and 103
• PCM ground=Test Pin 91
• Is resistance greater than 10,000 ohms?
Yes
REMOVE breakout box.
RECONNECT heated oxygen sensor.
REPLACE PCM.
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No REPLACE heated oxygen sensor.
REMOVE breakout box.
RECONNECT PCM.
RESET PCM to completely clear DTCs.
tr
After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
9
HEATED OXYGEN SENSOR CIRCUIT
CHECK (FOR RICH DTCS)
• Key off.
• Disconnect suspected heated oxygen
sensor. Inspect for damaged or pushed out
pins, corrosion and loose wires. Service as
necessary.
• NGS tester connected.
• Access suspected heated oxygen sensor
PID(s).
• 02S11 PID
• 02S21 PID
• Is reading 0.2 volt or less?
Yes Go to step 11.
No Short to power exists.
Go to next step.
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