Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P0102
MAF sensor circuit low input
DESCRIPTION
• DTC P0102 indicates MAF signal went below 0.39 volts (refer to Voltage to Mass Air Flow
Conversion Table) sometime during normal engine operation (Continuous)
[Possible Cause]
• Damaged MAF sensor • MAF circuit shorted to ground
• MAF sensor disconnected • Air Intake Leak (near MAF sensor)
• MAF circuit open • Throttle Position (TP) system (possible closed throttle
• Power circuit open indication)
• Ground circuit open • Damaged PCM
STEP INSPECTION
ACTION
1 CHECK MAF SIGNAL LOW INPUT TO PCM
• Check broken/loose air outlet tube clamps
(throttle body and air cleaner component
ends), cracks/holes in air outlet tube, worn
gaskets between MAF sensor and air
cleaner assembly. Service as necessary.
• Start engine and bring to idle.
Note
• If KOER DTC P0505 is present, go to
Diagnostic Trouble Code Charts. If
stabilized idle is not under 700 rpm, go to
ENGINE SYMPTOM
TROUBLESHOOTING.
• Run engine up 1 500 rpm for 5 seconds
then bring it back to idle.
• Access MAF V PID with NGS tester.
• Is MAF V PID less than 0.39 volts?
Yes
The MAF sensor signal is lower than acceptable minimum.
Go to next step.
No For KOER reading between 0.60 and 1.00 volt:
Go to step 10.
All others:
Go to step 13.
2 CHECK MAF SENSOR POWER CIRCUIT
VOLTAGE
• Key off.
• Disconnect MAF sensor.
• Key on, engine off.
• Measure voltage between power circuit at
MAF sensor vehicle harness connector
and battery negative post.
• Is voltage greater than 10.5 volts?
Yes
Power harness circuit from MAF sensor to battery
negative post is okay.
Go to next step.
No Service open power circuit.
RESET PCM to completely clear DTCs.
o ’ After Repair Procedure
COMPLETE OBD II Drive Mode.
RETURN OBD Test.
3 CHECK CONTINUITY OF MAF SENSOR
POWER CIRCUIT
• Key off.
• MAF sensor 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 power circuit
at the MAF sensor vehicle harness
connector and Test Pin 71 or 97 at the
breakout box.
• Is resistance less than 5.0 ohms?
Yes Power harness circuit to PCM is okay.
Go to next step.
No
Service open power harness circuit.
REMOVE breakout box.
RECONNECT all components.
RESET the PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
4 CHECK MAF SIGNAL CIRCUIT FOR
SHORTS TO GROUND CIRCUIT
• Key off.
• MAF sensor disconnected.
• Breakout box installed, PCM disconnected.
• Disconnect NGS tester from DLC.
• Measure the resistance between Test Pin
88 or Test Pins 36 and 24 or 103 at the
breakout box.
• Is each resistance greater than 10,000
ohms?
Yes MAF signal circuit and ground harness circuits to PCM are
okay.
RECONNECT NGS tester.
Go to next step.
No Service short circuit between MAF signal and ground.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
d
* After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
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