Pinpoint Test C: Incorrect Fuel Gauge Indication - Dual Fuel Tanks
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test C: Incorrect Fuel Gauge Indication - Dual Fuel Tanks
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information. Diagrams By Number
Normal Operation
The primary and secondary fuel level sensors are hardwired to the Instrument Panel Cluster (IPC) through the separate signal and return circuits. The fuel level sensors are variable resistors that range from 10 ohms ± 2 ohms at full (F) and 180 ohms ± 4 ohms at empty (E). The IPC provides a reference voltage to the primary fuel level sensor when the fuel selector switch is in the primary tank position and the secondary fuel level sensor when the fuel selector switch is in the secondary or auxiliary tank position on the respective signal circuit. As the fuel level changes, a float actuates a variable resistor on the fuel level sensors and raises or lowers the fuel level signal voltage depending on the resistance of the fuel level sensor that is currently monitored. The IPC monitors the changes in voltage and commands the fuel gauge with a corresponding movement of the pointer.
With dual tanks and dual fuel level inputs, the IPC requires a separate input to tell the IPC which tank to monitor. The IPC is hardwired to the fuel tank selector switch. When the secondary or auxiliary tank is selected, voltage is sent to the IPC from the fuel tank selector switch. When the primary tank is selected, voltage is removed and the input switched to ground through the fuel tank selector switch.
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 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 IPC 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 default 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 the following conditions be met:
- Engine speed input 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 60 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 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 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.
Instrument Panel Cluster (IPC) DTCs
PCM DTCs
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Fuel tank
- Fuel level sensor
- IPC
PINPOINT TEST C: INCORRECT FUEL GAUGE INDICATION - DUAL FUEL TANKS
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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C1 CHECK THE FUEL TANK SWITCHING SYSTEM
- NOTE: The vehicle may need to be operated In both modes to make sure that the fuel tanks are actually switching.
- Switch fuel tanks from the primary fuel tank to the auxiliary fuel tank and verify the fuel switching valve is switching tanks.
- Does the fuel tank switching system switch between primary and auxiliary fuel tanks?
Yes
GO to C2.
No
REFER to Fuel System - General Information - Gasoline and Diesel Testing and Inspection.
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C2 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST
- Retrieve the recorded IPC DTCs from the self-test.
- Are any DTCs recorded?
Yes
For DTC P0460:13, GO to C5. For DTC P0460:11, GO to C9. For DTC P1346:13, GO to C12. For DTC P1346:11, GO to C16. For all other DTCs, REFER to the DTC Charts.
No
GO to C3.
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C3 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.
- Select the IPC fuel gauge (FUELLEVEL) active command. Monitor the fuel gauge while scrolling the fuel level at 0%, 50%, and 100%.
- Does the fuel gauge display below E with 0%, half with 50%, and full stop with 100%?
Yes
GO to C4.
No
GO to C24.
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C4 CHECK THE FUEL TANK SELECTOR SWITCH INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: IPC C220.
- Ignition ON.
- Place the fuel tank selector switch in the secondary tank position.
- Measure the voltage between the IPC C220-10, circuit CE929 (VT/OG), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
If the fuel gauge is inaccurate from the primary tank position, GO to C21. If the fuel gauge is inaccurate from the secondary tank position, GO to C22. If the fuel gauge is inaccurate from the both tank positions, GO to C24.
No
REPAIR circuit CE929 (VT/OG) for an open. TEST the system for normal operation.
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C5 CHECK THE PRIMARY FUEL LEVEL SENSOR FOR AN OPEN
- Ignition OFF.
- Disconnect: Primary Fuel Level Sensor C3094.
- Place the fuel tank selector switch in the primary tank position.
- Connect a fused jumper wire between the primary fuel level sensor C3094-2, circuit VMC11 (YE/VT), harness side and the primary fuel level sensor C3094-1, circuit RMC32 (GN/BU), harness side.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IPC Self-Test.
- NOTE: DTC P0460:13 may also be present when carrying out this test step and should be ignored.
- Clear the IPC DTCs. Repeat the IPC self-test.
- Is DTC P0460:11 retrieved?
Yes
REMOVE the jumper wire. GO to C19.
No
REMOVE the jumper wire. GO to C6.
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C6 CHECK THE PRIMARY FUEL LEVEL SENSOR SIGNAL AND RETURN CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: IPC C220.
- Ignition ON.
- Measure the voltage between the IPC C220-12, circuit VMC11 (YE/VT), harness side and ground; and between the IPC C220-25, 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 C7.
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C7 CHECK THE PRIMARY FUEL LEVEL SENSOR SIGNAL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IPC C220-12, circuit VMC11 (YE/VT), harness side and the primary fuel level sensor C3094-2, circuit VMC11 (YE/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to C8.
No
REPAIR circuit VMC11 (YE/VT) for an open. CLEAR the DTCs. REPEAT the self-test.
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C8 CHECK THE PRIMARY FUEL LEVEL SENSOR RETURN CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IPC C220-25, circuit RMC32 (GN/BU), harness side and the primary fuel level sensor C3094-1, circuit RMC32 (GN/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to C24.
No
REPAIR circuit RMC32 (GN/BU) for an open. CLEAR the DTCs. REPEAT the self-test.
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C9 CHECK THE PRIMARY FUEL LEVEL SENSOR FOR A SHORT TO GROUND
- Ignition OFF.
- Place the fuel tank selector switch in the primary tank position.
- Disconnect: Primary Fuel Level Sensor C3094.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IPC Self-Test.
- NOTE: DTC P0460:11 may also 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
GO to C19.
No
GO to C10.
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C10 CHECK THE PRIMARY FUEL LEVEL SENSOR SIGNAL AND RETURN CIRCUITS FOR A SHORT TOGETHER
- Ignition OFF.
- Disconnect: IPC C220.
- Measure the resistance between the IPC C220-12, circuit VMC11 (YE/VT), harness side and the IPC C220-25, circuit RMC32 (GN/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to C11.
No
REPAIR the circuits for a short together. CLEAR the DTCs. REPEAT the self-test.
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C11 CHECK THE PRIMARY FUEL LEVEL SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
- Measure the resistance between the IPC C220-12, circuit VMC11 (YE/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to C24.
No
REPAIR circuit VMC11 (YE/VT) for a short to ground. CLEAR the DTCs. REPEAT the self-test.
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C12 CHECK THE SECONDARY FUEL LEVEL SENSOR FOR AN OPEN
- Ignition OFF.
- Disconnect: Secondary Fuel Level Sensor C433.
- Connect a fused jumper wire between the secondary fuel level sensor C433-2, circuit VMC23 (GN/OG), harness side and the secondary fuel level sensor C433-1, circuit RMC33 (WH/VT), harness side.
- Ignition ON.
- Place the fuel tank selector switch in the secondary tank position.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IPC Self-Test.
- NOTE: DTC P1346:13 to be present when carrying out this test step and should be ignored.
- Clear the IPC DTCs. Repeat the IPC self-test.
- Is DTC P1346:11 retrieved?
Yes
REMOVE the jumper wire. GO to C19.
No
REMOVE the jumper wire. GO to C13.
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C13 CHECK THE SECONDARY FUEL SENSOR SIGNAL AND RETURN CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: IPC C220 .
- Ignition ON.
- Measure the voltage between the IPC C220-13, circuit VMC23 (GN/OG), harness side and ground; and between the IPC C220-26, circuit RMC33 (WH/VT), 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 C14.
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C14 CHECK THE SECONDARY FUEL SENSOR SIGNAL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IPC C220-13, circuit VMC23 (GN/OG), harness side and the secondary fuel level sensor C433-2, circuit VMC23 (GN/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to C15.
No
REPAIR circuit VMC23 (GN/OG) for an open. CLEAR the DTCs. REPEAT the self-test.
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C15 CHECK THE SECONDARY FUEL SENSOR RETURN CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IPC C220-26, circuit RMC33 (WH/VT), harness side and the secondary fuel level sensor C433-1, circuit RMC33 (WH/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to C24.
No
REPAIR circuit RMC33 (WH/VT) for an open. CLEAR the DTCs. REPEAT the self-test.
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C16 CHECK THE SECONDARY FUEL LEVEL SENSOR FOR A SHORT TO GROUND
- Ignition OFF.
- Place the fuel tank selector switch in the secondary tank position.
- Disconnect: Secondary Fuel Level Sensor C433.
- Ignition ON.
- Wait one minute.
- Enter the following diagnostic mode on the scan tool: IPC Self-Test .
- NOTE: DTC P1346:11 may also be present when carrying out this test step and should be ignored.
- Clear the IPC DTCs. Repeat the IPC self-test.
- Is DTC P1346:13 retrieved?
Yes
GO to C19.
No
GO to C17.
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C17 CHECK THE SECONDARY FUEL SENSOR SIGNAL AND RETURN CIRCUITS FOR A SHORT TOGETHER
- Ignition OFF.
- Disconnect: IPC C220.
- Measure the resistance between the IPC C220-13, circuit VMC23 (GN/OG), harness side and the IPC C220-26, circuit RMC33 (WH/VT), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to C18.
No
REPAIR the circuits for a short together. CLEAR the DTCs. REPEAT the self-test.
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C18 CHECK THE SECONDARY FUEL SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
- Measure the resistance between the IPC C220-13, circuit VMC23 (GN/OG), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to C24.
No
REPAIR circuit VMC23 (GN/OG) for a short to ground. CLEAR the DTCs. REPEAT the self-test.
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C19 CHECK THE FUEL LEVEL SENSOR
NOTE: The fuel level sensor 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 level sensor in question (primary or secondary). Refer to Fuel Tank and Lines - Gasoline and Diesel Fuel Level Sensor.
- Measure the resistance between the fuel level sensor pin 1, component side, and the fuel level sensor pin 2, component side, while moving the float arm between the lower stop position and the upper stop position.
- Does the resistance slowly decrease from approximately 180 ohms to 10 ohms?
Yes
CHECK the fuel level sensor connector for corrosion, damaged or pushed out pins and REPAIR as necessary.
No
GO to C20.
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C20 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.
- NOTE: Disconnect the fuel level sender input wire from the fuel level sensor for this measurement.
- 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 level sensor. REFER to Fuel Tank and Lines - Gasoline and Diesel Fuel Level Sensor. CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new fuel level sender (float and card). CLEAR the DTCs. REPEAT the self-test.
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C21 CHECK THE FUEL LEVEL INPUT FROM THE PRIMARY FUEL LEVEL SENDER
NOTE: Since the IPC may be in anti-slosh fuel indication mode, the PID values may not match the fuel gauge readings. Disregard the actual gauge indication during this test step.
- Ignition OFF.
- Connect: IPC C220.
- Disconnect: Primary Fuel Level Sensor C3094.
- Place the fuel tank selector in the primary tank position.
- Connect one lead of the Instrument Gauge System Tester to the primary fuel level sensor C3094-2, circuit VMC11 (YE/VT), harness side and the other lead of the Instrument Gauge System Tester to the primary fuel level sensor C3094-1, 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.
- Monitor the IPC fuel level PID (FUELLVL1) with the gauge tester set at 180 ohms, 90 ohms, 55 ohms, 30 ohms, and 10 ohms.
- Does the PID begin at 0 and move approximately to 70, 127, 185, then 251?
Yes
GO to C22.
No
GO to C24.
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C22 CHECK THE FUEL LEVEL INPUT FROM THE SECONDARY FUEL LEVEL SENDER
NOTE: Since the IPC may be in anti-slosh fuel indication mode, the PID values may not match the fuel gauge readings. Disregard the actual gauge indication during this test step.
- Ignition OFF.
- Connect: IPC C220.
- Disconnect: Secondary Fuel Level Sensor C433.
- Connect one lead of the Instrument Gauge System Tester to the secondary fuel level sensor C433-2, circuit VMC23 (GN/OG), harness side and the other lead of the Instrument Gauge System Tester to the secondary fuel level sensor C433-1, circuit RMC33 (WH/VT), 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.
- Monitor the IPC fuel level PID (FUELLVL2) with the gauge tester set at 180 ohms, 90 ohms, 55 ohms, 30 ohms, and 10 ohms.
- Does the PID begin at 0 and move approximately to 70, 127, 185, then 251?
Yes
GO to C23.
No
GO to C24.
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C23 CHECK THE FUEL TANK
- Check the fuel tank for any damage or deformation.
- Is the fuel tank OK?
Yes
INSTALL a new primary or secondary fuel level sender in question. REFER to Fuel Tank and Lines - Gasoline and Diesel Fuel Level Sender. TEST the system for normal operation.
No
VERIFY the fuel level sender is OK. INSTALL a new fuel tank. REFER to Fuel Tank and Lines - Gasoline and Diesel Fuel Level Sender. CLEAR the DTCs. REPEAT the self-test.
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C24 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.
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