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 Instrument Cluster (IC) receives the fuel level signal from the fuel level sender (float and card), part of the fuel pump module. The fuel level sender 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). The fuel pump module receives a reference voltage from the IC through the fuel level signal circuit. As the fuel level changes, a float actuates a variable resistor that alters the fuel level signal voltage. The IC interprets the voltage change and commands the fuel gauge to sweep to the correct level.
On flex-fuel vehicles, basic fuel level indication is the same as gasoline vehicles, except that the flex-fuel vehicles require a DC-AC interface (internal to the IC), used to prevent chemical reactions created by the interaction of AC current with the fuel.
The IC 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 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 IC must receive a valid key ON fuel sender reading within one 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 60 seconds to read empty (E) to full (F)) requires 4 conditions be met:
- Engine speed input greater than 0 rpm.
- The transmission is in PARK (P) or NEUTRAL (N).
- 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) or NEUTRAL (N) 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 60 seconds to read from empty (E) to full (F). When the transmission is shifted out of PARK (P) or NEUTRAL (N), 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 IC strategy to recover from a missing fuel level input during a refueling event. Missing fuel level input 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 IC 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 (IC) DTCs
B1202-B1204:
PCM DTCs
P0460-P0463:
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Fuel level sender (float and card)
- Fuel pump module
- Fuel tank
- IC
PINPOINT TEST B: INCORRECT FUEL GAUGE INDICATION
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B1 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST
- Ignition OFF.
- Check for recorded IC DTCs from the self-test.
- Are any DTCs recorded?
Yes
For DTC B1202, GO to B3.
For DTC B1204, 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 IC FUEL GAUGE ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC fuel gauge (Fuel) active command and scroll the fuel gauge level to 0%, 20%, 80% and 100%.
- Does the fuel gauge display empty (E) with 0% approximately 1/4 tank with 20%, 3/4 tank with 80% and full (F) with 100%?
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 C4330.
- Connect a fused jumper wire between the fuel pump module C4330-2, circuit VMC11 (YE/VT), harness side and the fuel pump module C4330-1, circuit RMC32 (GN/BU), harness side.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IC Self-Test.
- NOTE: It may be normal for DTC B1202 to be present when carrying out this test step and should be ignored.
- Repeat the IC self-test. Clear the IC DTCs.
- Is DTC B1204 retrieved?
Yes
REMOVE the jumper wire. GO to B12.
No
REMOVE the jumper wire. GO to B4.
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B4 CHECK THE FUEL LEVEL SIGNAL AND RETURN CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: IC C220.
- Ignition ON.
- Measure the voltage between the IC C220-24, circuit VMC11 (YE/VT), harness side and ground; and between the IC C220-23, circuit RMC32 (GN/BU), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit in question for a short to voltage. CLEAR the DTCs. REPEAT the self-test.
No
GO to B5.
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B5 CHECK THE FUEL SIGNAL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IC C220-24, circuit VMC11 (YE/VT), harness side and the fuel pump module C4330-2, circuit VMC11 (YE/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B6.
No
REPAIR circuit VMC11 (YE/VT) for an open. CLEAR the DTCs. REPEAT the self-test.
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B6 CHECK THE FUEL LEVEL RETURN CIRCUIT FOR AN OPEN
- Measure the resistance between the IC C220-23, circuit RMC32 (GN/BU), harness side and the fuel pump module C4330-1, circuit RMC32 (GN/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B13.
No
REPAIR circuit RMC32 (GN/BU) for an open. CLEAR the DTCs. REPEAT the self-test.
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B7 CHECK THE FUEL PUMP MODULE FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Fuel Pump Module C4330.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IC Self-Test.
- NOTE: It may be normal for DTC B1204 to be present when carrying out this test step and should be ignored.
- Clear the IC DTCs. Repeat the IC self-test.
- Is DTC B1202 retrieved?
Yes
GO to B12.
No
GO to B8.
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B8 CHECK THE FUEL LEVEL SIGNAL CIRCUIT FOR A SHORT TO GROUND
- Disconnect: IC C220.
- Measure the resistance between the IC C220-24, circuit VMC11 (YE/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B9.
No
REPAIR circuit VMC11 (YE/VT) for a short to ground. CLEAR the DTCs. REPEAT the self-test.
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B9 CHECK THE FUEL LEVEL SIGNAL AND RETURN CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between the IC C220-24, circuit VMC11 (YE/VT), harness side and the IC 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 IC
NOTE: Since the IC 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 C4330.
- Connect 1 lead of the instrument gauge system tester to the fuel pump module assembly C4330-2, circuit VMC11 (YE/VT), harness side and the other lead to the fuel pump module assembly C4330-1, circuit RMC32 (GN/BU), harness side.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC 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.
- Monitor the IC fuel level PID (FUELLVL), with the gauge tester set at 180 ohms, 90 ohms, 55 ohms, 30 ohms and 10 ohms.
- Does the PID begin at approximately 0%, move to 25%, 50%, 75% then 100%?
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
GO to B12.
No
VERIFY the fuel pump module and fuel level sender (float and card) 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 CARD)
NOTE: The fuel level sender (float and card) 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. 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 increase from approximately 180 ohms to 10 ohms and remain within specification?
Yes
INSTALL a new fuel pump module. REFER to Fuel Delivery and Air Induction. CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new fuel level sender (float and card). REFER to Fuel Delivery and Air Induction. CLEAR the DTCs. REPEAT the self-test.
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B13 CHECK FOR CORRECT IC OPERATION
- Disconnect all the IC connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the IC 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 IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). 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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