Pinpoint Test B: Incorrect Fuel Gauge Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Test B: Incorrect Fuel Gauge Indication
Normal Operation
The fuel pump module is hardwired to the Instrument Panel Cluster (IPC) between independent signal and return circuits. The IPC (Instrument Panel Cluster) provides a reference voltage to the fuel pump module on the input circuit. As the fuel level changes, a float actuates a variable resistor that alters the fuel level signal voltage. The IPC (Instrument Panel Cluster) monitors the changes in voltage and commands the fuel gauge with a corresponding movement of the pointer.
The fuel level sender (float and card) measures variable resistance in the fuel tank depending on the current fuel level. When the fuel level is low, the resistance in the unit is high (180 ohms ± 4 ohms). When the fuel level is high, the resistance in the unit is low (10 ohms ± 2 ohms).
On flex-fuel vehicles, basic fuel level indication is the same as gasoline, except that the flex-fuel vehicles require a DC-AC interface (internal to the IPC (Instrument Panel Cluster)), used to prevent chemical reactions created by the interaction of AC current with the fuel.
The IPC (Instrument Panel 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.
Anti-Slosh Mode
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).
Key OFF Fueling Mode
The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires the following 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 IPC (Instrument Panel 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.
Key ON Fueling Mode
The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires the following conditions be met:
- Engine speed input is greater than 0 rpm.
- 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
Recovery mode is incorporated into the IPC (Instrument Panel Cluster) strategy to recover from a missing fuel level message during a refueling event. Missing fuel level messages 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 conditions are met:
- The IPC (Instrument Panel 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.
When the fuel gauge reads approximately 1/16th of a tank, the IPC (Instrument Panel Cluster) illuminates the low fuel warning indicator.
Instrument Panel Cluster (IPC) DTCs
PCM DTCs
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Fuel level sender (float and card)
- Fuel pump module
- Fuel tank
- IPC (Instrument Panel Cluster)
PINPOINT TEST B : INCORRECT FUEL GAUGE INDICATION
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: The fuel pump module may also be called the fuel tank unit.
B1 RETRIEVE THE RECORDED DTCs FROM THE IPC (Instrument Panel Cluster) SELF-TEST
- Ignition OFF.
- Check for recorded IPC (Instrument Panel Cluster) DTCs from the self-test.
Are any DTCs recorded?
Yes
For DTC P0460:11, GO to B2.
For DTC P0460:13, GO to B5.
For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to B9.
B2 CHECK THE FUEL TANK UNIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Fuel Pump Module C433.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) Self-Test.
- NOTE: It may be normal for DTC P0460:11 to be present when carrying out this test step and should be ignored.
Clear the IPC (Instrument Panel Cluster) DTCs. Repeat the IPC (Instrument Panel Cluster) self-test.
Is DTC P0460:13 retrieved?
Yes
GO to B13.
No
GO to B3.
B3 CHECK THE INPUT CIRCUIT FOR A SHORT TO GROUND
- Disconnect: IPC (Instrument Panel Cluster) C220.
- Measure the resistance between the IPC (Instrument Panel Cluster) C220-24, circuit VMC11 (YE/VT), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to B4.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
B4 CHECK THE INPUT AND RETURN CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between the IPC (Instrument Panel Cluster) C220-24, circuit VMC11 (YE/VT), harness side and the IPC (Instrument Panel Cluster) C220-23, circuit RMC32 (GN/BU), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to B15.
No
REPAIR the circuits. CLEAR the DTCs. REPEAT the self-test.
B5 CHECK THE FUEL TANK UNIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Fuel Pump Module C433.
- Connect a fused jumper wire between the fuel pump module C433-2, circuit VMC11 (YE/VT), harness side and the fuel pump module C433-1, circuit RMC32 (GN/BU), harness side.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) Self-Test.
- NOTE: It may be normal for DTC P0460:13 to be present when carrying out this test step and should be ignored.
Repeat the IPC (Instrument Panel Cluster) self-test. Clear the IPC (Instrument Panel Cluster) DTCs.
Is DTC P0460:11 retrieved?
Yes
REMOVE the jumper wire. GO to B13.
No
REMOVE the jumper wire. GO to B6.
B6 CHECK THE INPUT AND RETURN CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: IPC (Instrument Panel Cluster) C220.
- Ignition ON.
- Measure the voltage between the IPC (Instrument Panel Cluster) C220-24, circuit VMC11 (YE/VT), harness side and ground; and between the IPC (Instrument Panel Cluster) C220-23, circuit RMC32 (GN/BU), harness side and ground.
Is any voltage present?
Yes
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
No
GO to B7.
B7 CHECK THE INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IPC (Instrument Panel Cluster) C220-24, circuit VMC11 (YE/VT), harness side and the fuel pump module C433-2, circuit VMC11 (YE/VT), harness side.
Is the resistance less than 5 ohms?
Yes
GO to B8.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
B8 CHECK THE RETURN CIRCUIT FOR AN OPEN
- Measure the resistance between the IPC (Instrument Panel Cluster) C220-23, circuit RMC32 (GN/BU), harness side and the fuel pump module C433-1, circuit RMC32 (GN/BU), harness side.
Is the resistance less than 5 ohms?
Yes
GO to B15.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
B9 CARRY OUT THE IPC (Instrument Panel Cluster) FUEL GAUGE ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) DataLogger.
- NOTE: Make sure to set the scan tool to full empty (E) before beginning this step.
Select the IPC (Instrument Panel Cluster) fuel gauge (FUELLEVEL) active command. Command the fuel gauge level in 25% increments.
Does the fuel gauge display match the command?
Yes
GO to B10.
No
GO to B15.
B10 CHECK THE FUEL LEVEL INPUT TO THE IPC (Instrument Panel Cluster)
NOTE: Since the IPC (Instrument Panel Cluster) may be in anti-slosh fuel indication mode, the PID values may not match the fuel gauge readings. The actual gauge indication should be disregarded during this test step.
- Ignition OFF.
- Disconnect: Fuel Pump Module C433.
- Connect one lead of the instrument gauge system tester to the fuel pump module C433-2, circuit VMC11 (YE/VT), harness side and the other lead to the fuel pump module C433-1, circuit RMC32 (GN/BU), harness side.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) DataLogger.
- NOTE: It is extremely important to confirm the gauge tester settings with an ohmmeter to make sure that the gauge tester is in the correct position. Failure to follow this check may result in inaccurate test results.
Select the IPC (Instrument Panel Cluster) fuel level (FUELLVL1) PID. Monitor the PID with the gauge tester set at 180 ohms, 90 ohms, 55 ohms, 30 ohms and 10 ohms.
Does the PID begin at 0, move to approximately 70, 127, 185, then 251?
Yes
DISCONNECT the instrument gauge tester. GO to B12.
No
DISCONNECT the instrument gauge tester. GO to B11.
B11 CHECK THE FUEL LEVEL SIGNAL AND RETURN CIRCUITS FOR HIGH RESISTANCE
- Ignition OFF.
- Disconnect: IPC (Instrument Panel Cluster) C220.
- Connect a fused jumper wire between the fuel pump module C433-2, circuit VMC11 (YE/VT), harness side and the fuel pump module C433-1, circuit RMC32 (GN/BU), harness side.
- Measure the resistance between the IPC (Instrument Panel Cluster) C220-24, circuit VMC11 (YE/VT), harness side and the IPC (Instrument Panel Cluster) C220-23, circuit RMC32 (GN/BU), harness side.
Is the resistance less than 5 ohms?
Yes
REMOVE the jumper wire. GO to B15.
No
REPAIR the circuits for high resistance. TEST the system for normal operation.
B12 CHECK THE FUEL TANK
- Check the fuel tank for any damage or deformation.
Is the fuel tank OK?
Yes
GO to B13.
No
VERIFY the fuel pump module and fuel level sensor (float and card) are OK. INSTALL a new fuel tank. CLEAR the DTCs. REPEAT the self-test.
B13 CHECK THE FUEL PUMP MODULE
NOTE: The fuel pump module resistance measures between 10 ohms ± 2 ohms at the upper stop position and 180 ohms ± 4 ohms at the lower stop position.
- Remove the fuel pump module.
- Measure the resistance between the fuel pump module pin 1, component side, and the fuel pump module pin 2, component side, while moving the float arm from the lower stop position to the upper stop position.
Does the resistance slowly decrease from approximately 180 ohms to 10 ohms?
Yes
CHECK the fuel pump module connector for corrosion, damaged or pushed out pins and REPAIR as necessary.
No
GO to B14.
B14 CHECK THE FUEL LEVEL SENDER
NOTE: The fuel level sender resistance measures between 10 ohms ± 2 ohms at the upper stop position and 180 ohms ± 4 ohms at the lower stop position.
- Disconnect the fuel level sender input wire from the fuel pump module.
- Measure the resistance between the fuel level sender connector pin 1, harness side and the fuel level sender connector pin 2, harness side while slowly moving the float arm between the lower and upper stop position.
Does the resistance slowly decrease from approximately 180 ohms to 10 ohms?
Yes
INSTALL a new fuel pump module. CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new fuel level sender (float and card). CLEAR the DTCs. REPEAT the self-test.
B15 CHECK FOR CORRECT IPC (Instrument Panel Cluster) OPERATION
- Disconnect all the IPC (Instrument Panel Cluster) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the IPC (Instrument Panel Cluster) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) . TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.