Pinpoint Test B: Incorrect Fuel Gauge Indication - L-Shaped Fuel Tank
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test B: Incorrect Fuel Gauge Indication - L-Shaped Fuel Tank
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information. Diagrams By Number
Normal Operation
The fuel pump module is hardwired to the Instrument Cluster (IC) between the signal circuit VMC11 (YE/VT) and the signal return circuit RMC32 (GN/BU), which is grounded internally within the IC. 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 IC 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 IC monitors the changes in voltage and commands the fuel gauge with a corresponding movement of the pointer.
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.
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 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.
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 placed into the PARK (P) position or when the parking brake is applied. 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 IC 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 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.
B1202-B1204:
P0460-P0463:
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Fuel pump module
- Fuel level sensor card
- Fuel tank
- IC
PINPOINT TEST B: INCORRECT FUEL GAUGE INDICATION - L-SHAPED FUEL TANK
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Following any fuel gauge repairs, remove fuse 26 (10A) for one minute then reinstall to reset the fuel gauge timers.
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B1 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND IC AND PCM SELF-TESTS
- Check for recorded IC and PCM DTCs from the continuous and on-demand self-tests.
- Are any DTCs recorded?
Yes
For DTC B1202, GO to B3.
For DTC B1204, GO to B8.
For DTC B2627, VERIFY that the IC is correctly configured for a single fuel tank sender.
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. Command the fuel gauge from 0% to 20%, 50%, 70% and 100% while observing the fuel gauge.
- Does the fuel gauge begin at (E) empty, move to approximately 1/4, 1/2, 3/4 and F (full)?
Yes
GO to B11.
No
GO to B14.
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B3 CHECK THE FUEL PUMP MODULE FOR AN OPEN
- Ignition OFF.
- Disconnect: Fuel Pump Module C3127.
- Connect a fused jumper wire between the fuel pump module C3127-1, circuit RMC32 (GN/BU), harness side and the fuel pump module C3127-2, circuit VMC11 (YE/VT), harness side.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IC Self-Test.
- NOTE: DTC B1202 may also be present when carrying out this step and should be ignored.
- Repeat the IC self-test.
- Retrieve the IC continuous DTCs.
- Is DTC B1204 retrieved?
Yes
REMOVE the jumper wire. GO to B13.
No
REMOVE the jumper wire. GO to B4.
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B4 CHECK CIRCUIT VMC11 (YE/VT) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: IC C220.
- Ignition ON.
- Measure the voltage between the IC C220-16, circuit VMC11 (YE/VT), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
No
GO to B5.
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B5 CHECK CIRCUIT RMC32 (GN/BU) FOR A SHORT TO VOLTAGE
- Measure the voltage between the IC C220-17, circuit RMC32 (GN/BU), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
No
GO to B6.
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B6 CHECK CIRCUIT VMC11 (YE/VT) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IC C220-16, circuit VMC11 (YE/VT), harness side and the fuel pump module assembly C3127-2, circuit VMC11 (YE/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B7.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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B7 CHECK CIRCUIT RMC32 (GN/BU) FOR AN OPEN
- Measure the resistance between the IC C220-17, circuit RMC32 (GN/BU), harness side and the fuel pump module assembly C3127-1, circuit RMC32 (GN/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B14.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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B8 CHECK THE FUEL PUMP MODULE FOR A SHORT TO GROUND
- Disconnect: Fuel Pump Module C3127.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IC Self-Test.
- NOTE: DTC B1204 may also be present when carrying out this step and should be ignored.
- Repeat the IC self-test.
- Retrieve the IC continuous DTCs.
- Is DTC B1202 retrieved?
Yes
GO to B13.
No
GO to B9.
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B9 CHECK CIRCUITS VMC11 (YE/VT) AND RMC32 (GN/BU) FOR A SHORT TOGETHER
- Disconnect: IC C220.
- Ignition OFF.
- Measure the resistance between the IC C220-16, circuit VMC11 (YE/VT), harness side and the IC C220-17, circuit RMC32 (GN/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B10.
No
REPAIR the circuits. CLEAR the DTCs. REPEAT the self-test.
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B10 CHECK CIRCUIT VMC11 (YE/VT) FOR A SHORT TO GROUND
- Measure the resistance between the IC C220-16, circuit VMC11 (YE/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B14.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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B11 CHECK THE FUEL LEVEL INPUT TO THE IC
NOTE: Since the IC may be in anti-slosh fuel indication mode, the self-test and tester 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 Assembly C3127.
- Connect one lead of the instrument gauge system tester to the fuel pump module assembly C3127-2, circuit VMC11 (YE/VT), harness side and the other lead to the fuel pump module assembly C3127-1, circuit RMC32 (GN/BU), harness side.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC PIDs.
- NOTE: It is extremely important to confirm the gauge tester settings with an ohmmeter to ensure 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 (FUELLVL1) PID, 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 system tester. GO to B12.
No
DISCONNECT the instrument gauge system tester. GO to B14.
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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 level sensor and fuel pump module are OK. INSTALL a new fuel tank. CLEAR the DTCs. REPEAT the self-test.
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B13 CHECK THE FUEL LEVEL SENSOR CARD
NOTE: The fuel level sensor card resistance measures between 180 ohms ± 4 ohms at the lower stop position and 10 ohms ± 2 ohms at the upper stop position.
- Remove the fuel pump module.
- NOTE: Disconnect the fuel level sensor card input wire from the fuel pump module for this measurement.
- Measure the resistance between the fuel level sensor card input wire and the fuel level sensor card ground while slowly moving the float arm between the lower and upper stop position.
- Does the resistance slowly decrease from approximately 180 ohms at the lower stop to 10 ohms at the upper stop?
Yes
INSTALL a new fuel pump module. CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new fuel level sensor card. CLEAR the DTCs. REPEAT the self-test.
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B14 CHECK FOR CORRECT IC OPERATION
- Disconnect the IC connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IC connector and make sure it seats 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.
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