Pinpoint Test B: Incorrect Fuel Gauge Indication
Instrumentation 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) provides a reference voltage to the fuel level sender (float and card), part of the fuel pump module, through the fuel level signal circuit. 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) and when the fuel level is high, the resistance in the unit is low (10 ohms± 2 ohms). As the fuel level changes, a float actuates the variable resistor, raising or lowering the fuel level signal voltage depending on the resistance of the fuel level sender (float and card).
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 the 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 the above 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 3 conditions be met:
- The transmission is in PARK (P) (automatic transmission), or the parking brake is applied (manual transmission).
- 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 in 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
Recovery mode is incorporated into the IC 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 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
PCM DTCs
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Fuel tank
- Fuel pump module
- Fuel level sender (float and card)
- IC
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: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery, Mounting and Cables Battery Disconnect.
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B1 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST
- Check the recorded IC DTCs from the self-test.
- Are any DTCs recorded?
Yes
For DTC B1202, GO to B3.
For DTC B1204, GO to B6.
For all other DTCs, REFER to DTC Charts. Diagnostic Trouble Code Tests and Associated Procedures
No
GO to B2.
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B2 CARRY OUT THE IC GAUGES 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 at 20%, 50% and 70%.
- Does the fuel gauge indicate approximately one-quarter tank at 20%, 1/2 tank at 50% and 3/4 tank at 70%?
Yes
GO to B8.
No
GO to B11.
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B3 CHECK THE FUEL PUMP MODULE FOR AN OPEN
NOTE: If the fused jumper wire fails, refer to the Wiring Diagrams to identify the possible cause of the circuit short. Diagrams By Number
- Ignition OFF.
- Disconnect: Fuel Pump Module C4033.
- NOTE: Be sure to locate and use a known good, clean ground source for this test. Failure to use a good ground may result in inaccurate test results.
- Connect a fused jumper wire between the fuel pump module C4033-2, circuit VMC11 (YE/VT), harness side and ground.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IC Self-Test.
- Clear the DTCs.
- Carry out the IC self-test diagnostics.
- NOTE: DTC B1202 may also be present when carrying out this step and should be ignored.
- Retrieve the continuous memory DTCs.
- Is DTC B1204 retrieved?
Yes
REMOVE the jumper wire. GO to B4.
No
REMOVE the jumper wire. GO to B5.
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B4 CHECK THE FUEL LEVEL SENDER AND PUMP GROUND FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the fuel pump module C4033-1, circuit GD174 (BK/WH), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to B10.
No
REPAIR circuit GD174 (BK/WH) for an open. TEST the system for normal operation.
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B5 CHECK THE FUEL LEVEL INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the fuel pump module C4033-2, circuit VMC11 (YE/VT), harness side and the IC C220b-7, circuit VMC11 (YE/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B11.
No
REPAIR circuit VMC11 (YE/VT) for an open. CLEAR the DTCs. REPEAT the self-test.
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B6 CHECK THE FUEL PUMP MODULE FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Fuel Pump Module C4033.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IC Self-Test.
- Clear the DTCs.
- Carry out the IC self-test diagnostics.
- NOTE: DTC B1204 may also be present when carrying out this step and should be ignored.
- Retrieve the continuous memory DTCs.
- Is DTC B1202 retrieved?
Yes
GO to B10.
No
GO to B7.
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B7 CHECK THE FUEL LEVEL INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the IC C220b-7, circuit VMC11 (YE/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B11.
No
REPAIR circuit VMC11 (YE/VT) for a short to ground. CLEAR the DTCs. REPEAT the self-test.
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B8 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.
- NOTE: Be sure to locate and use a known good, clean ground source for this test.
- Connect one lead of the instrument gauge system tester to fuel pump module C4033-2, circuit VMC11 (YE/VT), harness side. Connect the other lead to ground.
- 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 ensure that the gauge tester is in the correct position. Failure to follow this check may result in inaccurate test results.
- Select the fuel level PID (FUELLVL) and monitor the PID with the gauge tester set at 180 ohms, 90 ohms, 55 ohms, 30 ohms then 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 B9.
No
DISCONNECT the instrument gauge system tester. GO to B11.
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B9 INSPECT THE FUEL TANK FOR DAMAGE
- Visually inspect the fuel tank for any damage or deformation.
- Is the fuel tank OK?
Yes
GO to B10.
No
VERIFY the fuel level sender card and float arm are OK. INSTALL a new fuel tank. REFER to Fuel Tank and Lines Fuel Tank. TEST the system for normal operation.
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B10 CHECK THE FUEL LEVEL SENDER
- Ignition OFF.
- NOTE: The fuel level sender resistance will measure 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 Pump in Fuel Tank and Lines Fuel Pump.
- NOTE: Disconnect the fuel level sender input wire from the fuel pump module 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 stop and the upper stop position.
- Does the resistance slowly decrease from approximately 180 ohms to 10 ohms?
Yes
INSTALL a new fuel pump module. REFER to Fuel Pump in Fuel Tank and Lines Fuel Pump. TEST the system for normal operation.
No
INSTALL a new fuel level sender. TEST the system for normal operation.
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B11 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.
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