Pinpoint Test B: Incorrect Fuel Gauge Indication
Instrumentation, Message Center and Warning Chimes
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 receives a reference voltage signal from the Instrument Cluster (IC) through circuit 29 (YE/WH), and returns the fuel level signal to the IC through circuit 1843 (BK/OG). The fuel level is determined using a variable resistance fuel sensor (float and card), with an approximate resistance range between 15 ohms± 2 ohms at empty (E) and 160 ohms ± 4 ohms at full (F). The IC interprets the voltage change as the resistance changes in the fuel level sensor and commands the fuel gauge to sweep to the correct level.
Flex fuel vehicles use AC for the sending unit, which is then converted by the IC to DC. The direction of the current through the fuel level sensor is switched by the cluster at a rate of 50 Hz with 50% of the duty cycle in each direction. The IC senses the variable resistance of the fuel level sensor by supplying voltage across the pins of the fuel pump module. This voltage varies based upon the value of the fuel level sensor resistance, which is determined by the level of the fuel sensor float and the battery voltage.
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 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 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 15 ohms (± 2 ohms) and 160 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 3 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 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 refueling 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 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.
B1202-B1204:
P0460-P0463:
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Fuel pump module
- Fuel level sensor (float and card)
- Fuel tank
- 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.
NOTICE: The electrical power to the air suspension system must be turned off prior to hoisting, jacking or towing an air suspension vehicle. Failure to do so can result in unexpected inflation or deflation of the air springs, which can result in shifting of the vehicle during these operations. Failure to follow these instructions may result in personal injury.
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B1 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST
- Check for recorded IC DTCs from the self-test.
- Are any IC DTCs recorded?
Yes
If DTC B1202 is retrieved, GO to B3.
If DTC B1204 is retrieved, GO to B7.
For all other IC 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 INDICATOR CONTROL 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 command the fuel gauge to 20%, 50%, 70% and 100%.
- Does the fuel gauge start at E (empty) and move to 1/4, 1/2, 3/4 and F (full)?
Yes
GO to B10.
No
GO to B13.
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B3 CHECK THE FUEL PUMP MODULE FOR AN OPEN
WARNING: Before servicing a vehicle equipped with a fire suppression system, depower the system by following the procedure in Fire Suppression System. Failure to follow the instructions may result in serious personal injury. Procedures
- Ignition OFF.
- Disconnect: Fuel Pump Module C433.
- Connect a fused jumper wire between the fuel pump module C433-5, circuit 29 (YE/WH), harness side and the fuel pump module C433-8, circuit 1843 (BK/OG), 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.
- Clear the IC DTCs. Repeat the IC self-test.
- 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 CIRCUITS 29 (YE/WH) AND 1843 (BK/OG) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: IC C2220.
- Ignition ON.
- Measure the voltage between the IC C2220-26, circuit 29 (YE/WH), harness side and ground; and between the IC C2220-27, circuit 1843 (BK/OG), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test. If equipped with the fire suppression system, GO to B14.
No
GO to B5.
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B5 CHECK CIRCUIT 29 (YE/WH) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IC C2220-26, circuit 29 (YE/WH), harness side and the fuel pump module C433-5, circuit 29 (YE/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B6.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. If equipped with the fire suppression system, GO to B14.
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B6 CHECK CIRCUIT 1843 (BK/OG) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IC C2220-27, circuit 1843 (BK/OG), harness side and the fuel pump module C433-8, circuit 1843 (BK/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B13.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test. If equipped with the fire suppression system, GO to B14.
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B7 CHECK THE FUEL PUMP MODULE FOR A SHORT TO GROUND
WARNING: Before servicing a vehicle equipped with a fire suppression system, depower the system by following the procedure in Fire Suppression System. Failure to follow the instructions may result in serious personal injury. Procedures
- Ignition OFF.
- Disconnect: Fuel Pump Module C433.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC Self-Test.
- Wait one minute.
- NOTE: DTC B1204 may also be present when carrying out this 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 CIRCUIT 29 (YE/WH) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: IC C2220.
- Measure the resistance between the IC C2220-26, circuit 29 (YE/WH), 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. If equipped with the fire suppression system, GO to B14.
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B9 CHECK CIRCUITS 29 (YE/WH) AND 1843 (BK/OG) FOR A SHORT TOGETHER
- Measure the resistance between the IC C2220-26, circuit 29 (YE/WH), harness side and the IC C2220-27, circuit 1843 (BK/OG), 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. If equipped with the fire suppression system, GO to B14.
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B10 CHECK THE FUEL LEVEL INPUT TO THE IC
WARNING: Before servicing a vehicle equipped with a fire suppression system, depower the system by following the procedure in Fire Suppression System. Failure to follow the instructions may result in serious personal injury. Procedures
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 C433.
- Connect one lead of the instrument gauge system tester to the fuel pump module assembly C433-8, circuit 1843 (BK/OG), harness side. Connect the other lead to the fuel pump module assembly C433-5, circuit 29 (YE/WH), 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 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 15 ohms, 53 ohms, 85 ohms, 115 ohms and 160 ohms.
- Does the PID begin at approximately 0%, move to 25%, 50%, 75%, then 100%?
Yes
GO to B11.
No
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, fuel level sensor and float arm are OK. INSTALL a new fuel tank. TEST the system for normal operation. If equipped with the fire suppression system, GO to B14.
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B12 CHECK THE FUEL LEVEL SENSOR
- NOTE: The fuel level sensor resistance will measure between 15 ohms ± 2 ohms at the lower stop position and 160 ohms ± 4 ohms at the upper stop position.
- Remove the fuel pump module.
- NOTE: Disconnect the fuel level sensor 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 ground while slowly moving the float between the lower stop and the upper stop position.
- Does the resistance slowly increase from approximately 15 ohms to 160 ohms?
Yes
INSTALL a new fuel pump module. CLEAR the DTCs. REPEAT the self-test. If equipped with the fire suppression system, GO to B14.
No
INSTALL a new fuel level sensor (float and card). CLEAR the DTCs. REPEAT the self-test. If equipped with the fire suppression system, GO to B14.
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B13 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. If equipped with the fire suppression system, GO to B14.
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. If equipped with the fire suppression system, GO to B14.
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B14 REPOWER THE FIRE SUPPRESSION SYSTEM
WARNING: If the vehicle is equipped with a fire suppression system, repower the system. For important safety warnings and procedures, refer to Fire Suppression System. Failure to follow these instructions may result in serious personal injury. Procedures
- Verify that the fire suppression system is repowered. Refer to Fire Suppression System. Procedures
- Is the fire suppression system repowered?
Yes
The fire suppression system repowering is complete.
No
REFER to Fire Suppression System for the fire suppression system depowering and repowering procedure. Procedures
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