HX76 - HX80

HX76 - DTC P0460: Check Fuel Tank Level Indicators

Diagnostic Trouble Code (DTC) P0460 indicates a fuel level input (FLI) circuit malfunction due to a low or high FLI circuit input to the PCM, or a mechanically stuck fuel pump (FP) module. Possible causes:
- Empty fuel tank.
- Overfilled fuel tank.
- Mechanically stuck open or closed FP module.
- Incorrect fuel gauge.
- Damaged fuel gauge or instrument cluster.
- FLI circuit open.
- CASE GND circuit open.
- FLI circuit shorted to CASE GND or PWR GND.
- FLI shorted to VPWR.
- CASE GND shorted to VPWR.
- Damaged PCM.

- Connect scan tool.
- Key on, engine off.
- Observe and record fuel gauge reading.
- Access FLI PID.

Are both the fuel gauge and the FLI PID indicating between one quarter (25% on FLI PID) and three quarters (75% on FLI PID) filled?

YES GO to HX78.
NO INSPECT fuel tank for leaks with the key off. REPAIR fuel tank if necessary.

For DTC P0460:

GO to HX77.

For fuel gauge inoperative without a DTC P0460:

GO to Chart 15 of the Diagnostic Routines (Diagnosis By Symptom). 15 - Instrumentation

HX77 - Check For Low Fuel Level

- Key on, engine off.
- While observing both the fuel gauge and FLI PID, add fuel [7.57 to 11.36 liters (2 to 3 gallons)] to the fuel tank.
- Key off.

Did either the fuel gauge or FLI PID indicate a movement upward as the fuel is added?

YES The fuel level in the tank ranges from low to empty. DRAIN or FILL the fuel tank from 25 to 75% level. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test. If DTC P0460 is still present, GO to HX79.
NO GO to HX81.

HX78 - Check FLI Voltage On The Scan Tool

- Key on, engine running.
- Access the FLI V PID.
- Key off.

Was the FLI V PID voltage between 0.90 and 2.45 volts (6.35 and 4.55 volts on Contour/Mystique)?

YES CHECK for a mechanically stuck fuel pump (FP) Module. REPAIR or REPLACE fuel pump assembly as necessary. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.
NO GO to HX79 .

HX79 - FLI Circuit Voltage Comparison Check At Breakout Box And Scan Tool

- Install breakout box, connect PCM to breakout box.
- Key on, engine running.
- Access FLI V PID.
- Measure voltage between PCM test pins 12 (or 9) and 91.
- Key off.

Were both voltage readings at breakout box and scan tool between 0.90 and 2.45 volts (6.35 and 4.55 volts on Contour/Mystique)?

YES GO to HX80.
NO CHECK for installation of proper fuel gauge. If fuel gauge is replaced, RERUN Pinpoint Test Step HX79. Otherwise, continue diagnosis below.

For only one of the voltage readings not within the specified range:

REPLACE PCM. RESTORE vehicle. RERUN Quick Test.

For both voltage readings not within the specified range:

GO to HX81.

HX80 - Case Gnd Circuit Voltage Comparison Check At Breakout Box And Scan Tool

- Key on, engine running.
- Access CAS GND PID.
- Measure voltage between PCM test pins 25 and 91.
- Key off.

Were both voltage readings at breakout box and scan tool less than or equal to 0.30 volt?

YES RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test. If DTC P0460 is still present, GO to the Electrical/Instrumentation Group in the Workshop Manual or Electrical and Vacuum Troubleshooting Manual, case ground diagnosis.
NO For only one of the voltage readings greater than 0.30 volt:

REPLACE PCM. RESTORE vehicle. RERUN Quick Test.

For both voltage readings greater than 0.30 volt:

GO to HX81.