Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P0460 Fuel gauge sender unit circuit malfunction (Open/short and functional)
DESCRIPTION
• DTC P0460 indicates fuel level input circuit malfunction due to low or high fuel level input
circuit input to PCM or mechanically stuck fuel pump
[Possible Cause]
• Empty fuel tank • Damaged fuel gauge or instrument cluster
• Overfilled fuel tank • Fuel level input circuit open
• Fuel pump mechanically stuck open • Fuel level input circuit shorted to pround circuit
• Fuel pump mechanically stuck closed • Fuel level input shorted to power circuit
• Incorrect fuel gauge • Damaged PCM
STEP
INSPECTION ACTION
1 VERIFICATION OF FUEL TANK LEVEL
• Key on, engine off.
• Record vehicle fuel gauge reading.
• If during initial 30 seconds of both readings,
fuel gauge is between one quarter and
three quarters filled but fuel level input PID
indicates much higher or lower reading
(approximately 100% or 0%), check fuel
pump resistance. Access fuel level input
PID NGS tester.
• Is fuel level in fuel tank between one
quarter (25% on FLI PID) and three
quarters (75% on FLI PID) filled?
Yes Go to next step.
No INSPECT fuel tanks for leaks. SERVICE as necessary.
EVALUATE fuel tank for overfilled condition (greater than
75%).
ADD fuel tank for under filled condition (less than 25%).
RERUN OBD Test.
Go to next step.
2
CHECK FUEL LEVEL INPUT VOLTAGE
• Key on, engine off.
• Access FLI V PID.
•
Is FLI V PID voltage between 1.24 and
2.90 volts?
Yes
CHECK for mechanically stuck fuel pump.
No Go to next step.
3
COMPARE FUEL LEVEL INPUT CIRCUIT
VOLTAGE CHECK AT BREAKOUT BOX AND
NGS TESTER
• Key off.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion and loose wires.
Service as necessary.
• Install breakout box. Connect PCM to
breakout box.
• Key on, engine off.
• Measure voltage between Test Pin 63 and
Test Pin 91 at breakout box.
• Are both voltage readings at breakout
box and NGS tester between 1.24 and
2.90 volts?
Yes Go to next step.
No For either voltage reading greater than 10 volts:
CHECK for installation of proper fuel gauge at instrument
cluster.
REPLACE fuel gauge when necessary.
RERUN Pinpoint test step 3.
For either voltage reading greater than 2.90 volts or
less than 1.24 volts:
REMOVE breakout box.
REPLACE PCM.
RERUN OBD test.
For both voltage readings greater than 2.90 volts or
less than 1.24 volts:
Check fuel pump resistance.
01-01A-79