Test A: Incorrect Fuel Gauge Indication

PINPOINT TEST A: INCORRECT FUEL GAUGE INDICATION

A1:

A2-A4:

A4-A5:

A6-A9:

A9-A11:

A11-A12:

Normal Operation
The fuel level sender receives a reference voltage signal from the instrument cluster through circuit VMC11 (YE/VT), and returns the fuel level signal to the instrument cluster through circuit RMC32 (GN/BU). As the fuel level changes, a float actuates a variable resistor that alters the fuel level signal voltage. The instrument cluster interprets this signal voltage and commands the fuel gauge to sweep to the correct level.

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 throughout the entire refueling of 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 15 ohms ±2 ohms and 160 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 3 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. 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), 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 during 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.

DTC B1202 - is a continuous and on-demand DTC that sets if the instrument cluster detects an out of range input caused by an open or short to voltage on circuit VMC11 (YE/VT).

DTC B1204 - is a continuous and on-demand DTC that sets if the instrument cluster detects an out of range input caused by a short to ground on circuit VMC11 (YE/VT).

Possible Causes
- Circuit VMC11 (YE/VT) open, short to ground or voltage
- Circuit RMC32 (GN/BU) open or short to voltage
- Fuel level sensor
- Fuel pump module
- Fuel tank
- Instrument cluster