Test B: Incorrect Fuel Gauge Indication - Sedan

PINPOINT TEST B: INCORRECT FUEL GAUGE INDICATION - SEDAN

Normal Operation
The fuel pump module is hardwired to the instrument cluster between the signal circuit VMC11 (YE/VT) and the signal return circuit RMC32 (GN/BU), which is grounded internally within the instrument cluster. The fuel level sensor card is a variable resistor attached to the fuel pump module that ranges from 180 ohms ± 4 ohms at empty (E) and 10 ohms ± 2 ohms at full (F). The instrument cluster provides a reference voltage to the fuel pump module on circuit VMC11 (YE/VT). As the fuel level changes, a float actuates a variable resistor on the fuel level sensor card and raises or lowers the fuel level signal voltage depending on the resistance of the fuel level sensor. The instrument cluster monitors the changes in voltage and commands the fuel gauge with a corresponding movement of the pointer.

The instrument cluster uses 4 different operating modes to calculate the fuel level:
- Anti-slosh (default mode)
- Key OFF fueling
- Key ON fueling
- Recovery

After a fuel fill up, the time for the fuel gauge to move from empty (E) to full (F) ranges from 2 seconds to 55 minutes depending on which operating mode the fuel gauge is in.

The default fuel gauge mode is called the anti-slosh mode. To prevent fuel gauge changes from fuel slosh (gauge instability due to changes in fuel sender readings caused by fuel moving around in the tank), the fuel gauge takes approximately 55 minutes to go from empty (E) to full (F).

The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires 3 conditions be met:
- The key must be in the OFF position when refueling the vehicle.
- At least 15% of the vehicle's fuel capacity must be added to the fuel tank.
- The instrument cluster must receive a valid key ON fuel sender reading within 1 second of the key being put into the RUN position. The key ON sample readings are considered valid if the fuel sender reading is between 10 ohms ± 2 ohms and 180 ohms ± 4 ohms.

If these conditions are not met, the fuel gauge stays in the anti-slosh mode, which results in a slow to read full (F) event.

The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires the following conditions be met:
- The transmission is in PARK (P).
- The key is in the RUN position.
- At least 15% of the vehicle's fuel capacity must be added to the fuel tank.

In key ON fueling mode, a 30-second timer activates after the transmission is put into the PARK (P) position (automatic transmissions) or when the parking brake is applied (manual transmissions). When the 30 second time has elapsed and at least 15% of the vehicle's fuel capacity has been added, the fuel gauge response time is 90 seconds to read from empty (E) to full (F). When the transmission is shifted out of PARK (P) or the parking brake is released, the fuel gauge strategy reverts to the anti-slosh mode. The key ON fueling mode prevents slow to read full events from happening if the customer refuels the vehicle with the key in the RUN position.

Recovery mode is incorporated into the instrument cluster strategy to recover from a missing fuel level input after a refueling event. Missing fuel level inputs result from intermittent opens in the fuel sender or its circuits. Recovery mode (empty [E] to full [F] approximately 20 minutes) is initiated when the following 2 conditions are met:
- The instrument cluster is in the anti-slosh (default) mode.
- The actual fuel level in the tank is greater than what is being displayed by the fuel gauge.

Instrument Cluster DTCs
- DTC B1202 (Fuel Sender Circuit Open) - is a continuous and on-demand DTC that sets in the instrument cluster if the instrument cluster detects that the fuel sender is out of range on input circuit VMC11 (YE/VT) with an open or short to voltage on circuits VMC11 (YE/VT) or RMC32 (GN/BU) for more than 33 seconds. The instrument cluster defaults the fuel gauge to empty (E), once the instrument cluster detects a fault and sets DTC B1202.
- DTC B1204 (Fuel Sender Circuit Short to Ground) - is a continuous and on-demand DTC that sets in the instrument cluster if the instrument cluster detects that the fuel sender is out of range on input circuit VMC11 (YE/VT) with short to ground for more than 33 seconds. The instrument cluster defaults the fuel gauge to empty (E), once the instrument cluster detects a fault and sets DTC B1204.

PCM DTCs
- DTC P0460 (Fuel Level Sensor A Circuit) - sets when the PCM determines the value of the fuel level input signal is stuck, that the fuel level input signal does not change or does not correspond with the calculated fuel usage.
- DTC P0461 (Fuel Level Sensor A Circuit Range/Performance) - sets when the PCM determines the fuel level input signal repeatedly moves in and out of range, exceeding the minimum or maximum allowable calibrated parameters for a specified fuel fill percentage in the fuel tank.
- DTC P0462 (Fuel Level Sensor A Circuit Low) - sets in the PCM when the PCM detects a short to ground on the fuel pump module signal circuit based on the messaged input received from the instrument cluster.
- DTC P0463 (Fuel Level Sensor A Circuit High) - sets in the PCM when the PCM detects an open or a short to voltage on the fuel pump module signal circuit based on the messaged input received from the instrument cluster.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Fuel pump module
- Fuel level sensor card
- Fuel tank
- Instrument cluster

B1-B3:

B3-B6:

B6-B9:

B9-B11:

B11-B13:

B13-B14: