Pinpoint Test B: Incorrect Fuel Gauge Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test B: Incorrect Fuel Gauge Indication
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information Diagrams By Number.
Normal Operation
The fuel pump module (gasoline) or fuel level sensor (diesel) is hardwired to the Instrument Panel Cluster (IPC) between independent signal and return circuits. The IPC provides a reference voltage to the fuel pump module (gasoline) or fuel level sensor (diesel) on the input circuit. As the fuel level changes, a float actuates a variable resistor that alters the fuel level signal voltage. The IPC 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 and diesel vehicles, except that the flex-fuel vehicles require a DC-AC interface (internal to the IPC), used to prevent chemical reactions created by the interaction of AC current with the fuel.
The IPC 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 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 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 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 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) (gasoline)
- Fuel level sensor (diesel)
- Fuel pump module
- Fuel tank
- IPC
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.
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B1 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST
- Ignition OFF.
- Check for recorded IPC DTCs from the self-test.
- Are any DTCs recorded?
Yes
For DTC P0460:13, GO to B3.
For DTC P0460:11, GO to B7.
For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to B2.
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B2 CARRY OUT THE IPC FUEL GAUGE ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger.
- NOTE: Make sure to set the scan tool to full empty (E) before beginning this step.
- Select the IPC 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 B13.
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B3 CHECK THE FUEL TANK UNIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Fuel Pump Module C433 (Gasoline).
- Disconnect: Fuel Level Sensor C434 (Diesel).
- For gasoline, 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.
- For diesel, connect a fused jumper wire between the fuel level sensor C434-2, circuit VMC11 (YE/VT), harness side and the fuel level sensor C434-3, circuit RMC32 (GN/BU), harness side.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IPC 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 self-test. Clear the IPC DTCs.
- Is DTC P0460:11 retrieved?
Yes
REMOVE the jumper wire.
For gasoline or flex-fuel engines, GO to B12.
For diesel engines, INSTALL a new fuel level sensor. REFER to Fuel Delivery and Air Induction. CLEAR the DTCs. REPEAT the self-test.
No
REMOVE the jumper wire. GO to B4.
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B4 CHECK THE INPUT AND RETURN CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: IPC C220.
- Ignition ON.
- Measure the voltage between the IPC C220-24, circuit VMC11 (YE/VT), harness side and ground; and between the IPC 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 B5.
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B5 CHECK THE INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- For gasoline, measure the resistance between the IPC C220-24, circuit VMC11 (YE/VT), harness side and the fuel pump module C433-2, circuit VMC11 (YE/VT), harness side.
- For diesel, measure the resistance between the IPC C220-24, circuit VMC11 (YE/VT), harness side and the fuel level sensor C434-2, circuit VMC11 (YE/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B6.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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B6 CHECK THE RETURN CIRCUIT FOR AN OPEN
- For gasoline, measure the resistance between the IPC C220-23, circuit RMC32 (GN/BU), harness side and the fuel pump module C433-1, circuit RMC32 (GN/BU), harness side.
- For diesel, measure the resistance between the IPC C220-23, circuit RMC32 (GN/BU), harness side and the fuel level sensor C434-3, circuit RMC32 (GN/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B13.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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B7 CHECK THE FUEL TANK UNIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Fuel Pump Module C433 (Gasoline).
- Disconnect: Fuel Level Sensor C434 (Diesel).
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IPC 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 DTCs. Repeat the IPC self-test.
- Is DTC P0460:13 retrieved?
Yes
For gasoline and flex-fuel, GO to B12.
For diesel, INSTALL a new fuel level sensor. REFER to Fuel Delivery and Air Induction. TEST the system for normal operation.
No
GO to B8.
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B8 CHECK THE INPUT CIRCUIT FOR A SHORT TO GROUND
- Disconnect: IPC C220.
- Measure the resistance between the IPC C220-24, circuit VMC11 (YE/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B9.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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B9 CHECK THE INPUT AND RETURN CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between the IPC C220-24, circuit VMC11 (YE/VT), harness side and the IPC C220-23, circuit RMC32 (GN/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B13.
No
REPAIR the circuits. CLEAR the DTCs. REPEAT the self-test.
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B10 CHECK THE FUEL LEVEL INPUT TO THE IPC
NOTE: Since the IPC 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 (Gasoline).
- Disconnect: Fuel Level Sensor C434 (Diesel) .
- For gasoline, 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.
- For diesel, connect one lead of the instrument gauge system tester to the fuel level sensor C434-2, circuit VMC11 (YE/VT), harness side and the other lead to the fuel level sensor C434-3, circuit RMC32 (GN/BU), harness side.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC 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 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 B11.
No
DISCONNECT the instrument gauge tester. GO to B13.
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B11 CHECK THE FUEL TANK
- Check the fuel tank for any damage or deformation.
- Is the fuel tank OK?
Yes
If equipped with a gasoline engine, GO to B12.
If equipped with a diesel engine, INSTALL a new fuel level sensor. REFER to Fuel Delivery and Air Induction. CLEAR the DTCs. REPEAT the self-test.
No
VERIFY the fuel pump module and fuel level sensor (float and card) (gasoline) or fuel level sensor (diesel) are OK. INSTALL a new fuel tank. REFER to Fuel Delivery and Air Induction. CLEAR the DTCs. REPEAT the self-test.
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B12 CHECK THE FUEL LEVEL SENDER (FLOAT AND RESISTOR CARD)
- Remove the fuel pump module. Refer to Fuel Delivery and Air Induction.
- NOTE: Disconnect the fuel level sender input wire from the fuel level sender for this measurement.
- Measure the resistance between the fuel level sender input wire and the fuel level sender ground 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 and remain within specification?
Yes
INSTALL a new fuel pump module. CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new fuel level sender (float and resistor card). CLEAR the DTCs. REPEAT the self-test.
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B13 CHECK FOR CORRECT IPC OPERATION
- Disconnect all the IPC connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the IPC 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. REFER to Instrument Panel Cluster (IPC) 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.
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