Mazda MX-6 1998, Workshop Manual

Page: 43 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P0103 MAF sensor circuit high input
DESCRIPTION
• DTC P0103 indicates Mass Air Flow (MAF) sensor signal went above 4.35 volts during
normal engine operation (continuous) or during self-test (KOEO)
[Possible Cause]
• Blocked MAF sensor screen • MAF signal harness short to power circuit
• Damaged MAF sensor • Damaged PCM
STEP INSPECTION
ACTION
1 CHECK MAF SIGNAL HIGH INPUT TO PCM
• Start engine and bring to idle.
Note
• If KOER DTC P0505 is present, go to
Diagnostic Trouble Code Charts. If
stabilized idle is under 700 rpm, go to
ENGINE SYMPTOM
TROUBLESHOOTING.
• Run throttle up to 1500 rpm for 5 seconds,
and bring it back to idle.
• Access MAF
V
PID with NGS tester.
Note
• MAF
V
PID should be greater than 3.9
volts.
• Key off.
• Disconnect MAF sensor.
• Jumper ground and PCM ground (between
PCM and MAF sensor ground circuit) pins
at MAF sensor vehicle harness connector.
• Key on, engine running.
• Again access MAF
V
PID with NGS tester.
• Did MAF V PID drop from previous
reading below 0.39 volts?
Yes
MAF signal circuit shorted to power circuit in MAF sensor.
REMOVE Jumper.
REPLACE MAF sensor.
RESET PCM to completely clear DTCs.
c
r After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No
Power short circuit, but not in MAF sensor.
REMOVE Jumper.
Go to next step.
2 RERUN SELF-TEST WITH MAF SENSOR
DISCONNECTED
•
Key off.
•
Disconnect MAF sensor.
•
Disconnect PCM.
•
Inspect for damage or pushed out pins,
corrosion loose wires, etc. Service as
necessary.
•
Install breakout box. Leave PCM
disconnected.
•
Key on, engine off.
•
Measure voltage between Test Pin 88 and
Test pin 24 or 103 GND at breakout box.
•
Is voltage greater than 10.5 volts?
Yes SERVICE short between MAF signal and power circuit
(excluding constant voltage circuit) in harness circuit.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
¡ y
After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No Go to next step.
3 CHECK MAF SIGNAL CIRCUIT FOR SHORT
TO MAF SENSOR POWER CIRCUIT
•
Key off.
•
MAF sensor disconnected.
•
Disconnect NGS tester from DLC.
•
Measure resistance between Test Pin
88
and Test Pins 71 or 97 at breakout box.
•
Is resistance greater than 10,000 ohms?
Yes
MAF signal circuit shorted to power circuit in PCM.
REPLACE damaged PCM.
REMOVE breakout box.
RECONNECT MAF sensor.
RESET PCM to completely clear DTCs.
et
After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No
SERVICE short between MAF signal circuit and constant
voltage circuit in harness circuit.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
ey After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
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