Circuit Description
The left Fuel Level sensor, mounted in the rear side of the left fuel tank, measures fuel level changes within the left fuel tank. The left Fuel Level Sensor changes resistance based on fuel level. The Fuel Level Sensor has a signal circuit and a ground circuit. The PCM applies a voltage (about 5.0 volts) on the signal circuit to the sensor. The PCM monitors changes in this voltage caused by changes in the resistance of the sensor to determine fuel level.
When the fuel tank is full, the sensor resistance is high, and the PCM senses high signal voltage. When the fuel tank is empty, the sensor resistance is low, and the PCM senses a low signal voltage.
The PCM uses inputs from the Fuel Level Sensor to calculate the total fuel remaining in the fuel tank(s). This information is then sent to the fuel gauge via the class 2 circuit.
When the PCM senses a signal voltage lower than the normal operating range of the sensor, this DTC sets.
The following is a description on how the fuel pump/system functions: An electric high pressure fuel pump attaches to the fuel sender assembly inside the left fuel tank. The in-tank fuel pump supplies pressurized fuel through an in pipe fuel filter/pressure regulator assembly to the fuel rail. The fuel pressure supplied by the in-tank fuel pump exceeds the fuel injectors required pressure. The pressure regulator, which is part of the fuel filter assembly, regulates the fuel pressure supplied to the fuel injectors. Excess fuel returns from the fuel filter/pressure regulator, through a separate fuel return pipe, to the left fuel tank. The fuel pump delivers a constant flow of fuel to the engine even during low fuel conditions and aggressive vehicle maneuvers. The PCM controls the electric fuel pump operation through a fuel pump relay.
The left tank fuel pump also supplies a small amount of pressurized fuel to the right fuel tank siphon jet pump through the fuel feed rear crossover pipe. The pressurized fuel creates a venturi action inside the siphon jet pump. The venturi action causes the fuel to be drawn out of the right fuel tank. Fuel is then transferred from the right fuel tank to the left fuel tank through the fuel sender fuel feed pipe. The fuel system is designed to maintain a greater level in the left fuel tank then in the right fuel tank when the electric fuel pump is operating. The fuel transfer rate from the left fuel tank to the right fuel tank is less than the transfer rate from the right fuel tank to the left fuel tank. Therefore, with the electric fuel pump operating, the left fuel tank level should be higher than the right fuel tank level.
The fuel level in the fuel tanks equalize when the following occur:
| • | The electric fuel pump is not operating. |
| • | The fuel level is greater than 50%. |
Conditions for Running the DTC
The engine is operating.
Conditions for Setting the DTC
| • | The Primary fuel tank (left) is not full. |
| • | More than 241 km (150 miles) have been accumulated. |
| • | The PCM does not detect that the fuel level in the left fuel tank moved by at least 4.0 liters (1.1 gallons). |
OR
| • | The Primary fuel tank (left) is full. |
| • | The Secondary fuel tank (right) is near empty |
| • | The fuel level in both fuel tanks does not change after traveling more than 241 km (150 miles). Observe, if the secondary fuel tank is empty, the primary fuel level should decrease after 241 km (150 miles). |
Action Taken When the DTC Sets
| • | The PCM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
| • | The fuel gauge displays empty. |
| • | The Driver Information Center (DIC) displays a message. |
| • | The Check Gauge lamp illuminates. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
Diagnostic Aids
Important:
• Remove any debris from the PCM\TAC module connector surfaces before
servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets
when diagnosing/replacing the modules. Ensure that the gaskets are
installed correctly. The gaskets prevent contaminate intrusion into
the PCM\TAC modules. • For any test that requires probing the PCM or a component
harness connector, use the Connector Test Adapter Kit J 35616
. Using this kit prevents damage
to the harness/component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | The following may cause an intermittent: |
| - | Poor connections; Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
| - | Mis-routed harness. |
| - | Rubbed through wire insulation. |
| - | Broken wire inside the insulation. |
| • | Depending on the current fuel level, it may be difficult to locate a malfunctioning sending unit. The malfunction may only occur when the fuel level is full or near empty. The fuel sending unit may need to be removed for further diagnosis. A Fuel Level sensor that has an intermittent condition causes this DTC to set. Remove the Fuel Level sensor in order to test the resistance of the sensor. Refer to Fuel Sender Assembly Replacement . The resistance of the sensor should change from 40 to 250 ohms as the float arm is moved from the empty to full positions. Replace the sensor if the resistance did not change or is out of range. |
| • | The following occurs with this DTC set: |
| - | The vehicle fuel gauge displays empty. |
| - | The Check Gauge lamp illuminates. |
| - | The Driver Information Center displays a message. |
| • | The PCM will not reset the mileage for this diagnostic if the fuel tanks are re-fueled to the same level as before the repair was made. Perform the following procedure in order to re-fuel the vehicle after replacing a sending unit or fuel tank: |
| - | Add 25 percent of the fuel that you removed before the repair. |
| - | Start and idle the engine for 5 minutes. |
| - | Turn OFF the engine. |
| - | Add the remainder of the fuel. |
| • | The voltages in the Fuel Level Conversion Table are approximate values. Use this table to aid in diagnosis. |
Fuel Level Conversion Table | ||
|---|---|---|
Approximate Values | ||
Fuel Level | Left Tank voltage | Right Tank Voltage |
100% | 2.5V | 2.5V |
75% | 2.5V | 1.5V |
50% | 2.5V | Less than 1V |
25% | 1.7V | Less than 1V |
0% | Less than 1V | Less than 1V |
| • | Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. |
| • | For an intermittent, refer to Symptoms . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
The PCM set DTCs P0461 and P1431 if one of the following conditions exists:
-
This step determines if a circuit condition is causing the fuel level signal to be at a fixed value.
-
This step determines if a circuit condition is causing the fuel level signal to be at a fixed value.
-
This step determines if a circuit condition is causing the fuel level signal to be at a fixed value.
-
This step determines if a circuit condition is causing the fuel level signal to be at a fixed value.
-
This step determines if fuel is being transferred to the right fuel tank.
The fuel pump runs for 2 seconds each time it is commanded ON with the scan tool. The fuel pump must be enabled several times to achieve the time specified in the diagnostic table.
-
This step verifies that the left fuel level sender voltage is not above the specified value. If the left fuel level sender voltage is above the specified value, the left fuel tank will have to be drained.
-
This step determines if fuel is transferred to the left fuel tank.
The fuel pump runs for 2 seconds each time it is commanded ON using the scan tool. The fuel pump must be enabled several times to achieve the time specified in the diagnostic table.
-
The fuel level information is important for diagnosis. The fuel level information can determine how much fuel is remaining. Also, review failure records to determine how many miles have been traveled since the DTC set. Inquire with the customer for fuel level information. Refer to Diagnostic Aids for fuel level conversion table. Ask the customer the following questions:
-
The voltages at 2.5 volts indicates that the PCM and wiring are OK.
The Left Fuel Level sensor may be stuck within range (2.5V). The vehicle may need to be driven and retested before refueling, or fuel may be drained from the Left Tank as the Fuel Level Sensor voltage is monitored.
If the Left Fuel Level sender is not stuck, the following could be what caused the DTCs to set:
-
The fuel levels in each tank should equalize when the vehicle sets with the engine off for a couple of hours. The fuel level will not equalize as quick or at all if the fuel level is below 50 percent. It is important that the fuel level is greater than 50 percent before performing the next step.
-
Add the appropriate amount of fuel if the fuel level is below a half tank. Refer to Diagnostic Aids for fuel level conversion table. The values in this table are approximate values. You should be able to determine the fuel level even if there is a malfunctioning sensor. The fuel level information is important. The fuel levels in each tank should equalize when the vehicle sets with the engine off for a couple of hours. The fuel level will not equalize as quick or at all if the fuel level is below 50 percent.
-
Starting the engine allows fuel to transfer to the left fuel tank. The fuel transfer is greater to the left fuel tank then to the right fuel tank while the engine is operating. The engine must be started after fuel is added. This step tests if fuel level voltages change when the fuel tanks are equalizing. Once the fuel tanks equalize, and the engine is started, the left fuel tank level should increase and the right fuel level should decrease.
-
The fuel level sensors are not stuck if the fuel level increased for the left fuel tank and decreased for the right fuel tank. The following could have caused the DTCs to set:
-
This step determines if a circuit condition is causing the fuel level signal to be at a fixed value.
-
This step determines if a circuit condition is causing the fuel level signal to be at a fixed value.
-
This step determines if fuel is transferred to the right fuel tank.
The fuel pump runs for 2 seconds each time it is commanded ON with the scan tool. The fuel pump must be enabled several times to achieve the time specified in the diagnostic table.
-
This step determines if fuel is transferred to the left fuel tank.
The fuel pump runs for 2 seconds each time it is commanded ON using the scan tool. The fuel pump must be enabled several times to achieve the time specified in the diagnostic table.
-
The PCM will not reset the mileage for this diagnostic if the fuel tanks are re-fueled to the same level as before the repair was made. Perform the following procedure in order to re-fuel the vehicle after replacing a sending unit or fuel tank.
| • | No fuel transfer between fuel tanks (i.e. , Siphon Jet pump inoperative). |
| • | The left side Fuel Level sensor cannot obtain a predetermined upper threshold. |
| • | The right side Fuel Level sensor cannot obtain a predetermined lower threshold. |
| • | The left Fuel Level sensor is stuck in the full position. |
| • | Has the vehicle just been re-fueled (full tank)? |
| • | How many miles have been traveled since the last fill-up? |
| • | How many miles have been traveled since the LOW FUEL message appeared and the fuel gauge moved to empty? |
| • | The fuel tanks were over filled. |
| • | A fuel level that is almost empty and then re-fueled with only a couple gallons. |
| • | The fuel level sender un-stuck while re-fueling. |
| • | The fuel level sender became un-stuck on rough road or going around a corner. |
| • | The fuel tanks over filled. |
| • | Fuel level that is almost empty and then re-fueled with only a couple gallons. |
| • | The Fuel Level sender un-stuck while re-fueling. |
| • | The Fuel Level sender un-stuck on rough road or going around a corner. |
| 1. | Add 25 percent of the fuel that you removed before the repair. |
| 2. | Start and idle the engine for 5 minutes. |
| 3. | Turn OFF the engine. |
| 4. | Add the remainder of the fuel. |
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||||
Is DTC P1431 also set? | -- | |||||||||||||
Is the voltage at the specified voltage? | 0.0V | |||||||||||||
Is the voltage at the specified voltage? | 0.0V | |||||||||||||
Is the voltage near the specified voltage? | 0.0V | |||||||||||||
Is the voltage near the specified voltage? | 0.0V | |||||||||||||
|
Caution: Gasoline or gasoline vapors are highly flammable. A fire could occur if an ignition source is present. Never drain or store gasoline or diesel fuel in an open container, due to the possibility of fire or explosion. Have a dry chemical (Class B) fire extinguisher nearby.
Important: The scan tool will have to be commanded ON several times in order to achieve the time specified. Is the volume of fuel greater than the specified value? | 10 seconds 300 ml (0.633 pt) | |||||||||||||
Is the left fuel level sender voltage above the specified value? | 1.25V | |||||||||||||
9 | Drain the left fuel tank until the left fuel sender voltage is within the specified range. Refer to Fuel Tank Draining . Did you complete the action? | 1.0-1.25V | -- | |||||||||||
Important: The scan tool will have to be commanded ON several times in order to achieve the time specified. Is the volume of fuel greater than the specified value? | 8 seconds 332.6 ml (0.703 pt) | |||||||||||||
Reconnect the fuel sender fuel feed pipe (left tank to jet pump). Was the vehicle just re-fueled (Full tank) inquire with the customer? | -- | |||||||||||||
Turn ON the ignition leaving the engine OFF. Are both the fuel level sensor voltages near the specified voltage? | 2.5V | Go to Diagnostic Aids | ||||||||||||
Is the fuel level greater than 50%? | -- | |||||||||||||
Is the action complete? | -- | -- | ||||||||||||
Important: Observe and record both fuel level sensor voltages. Did the Fuel Level sensor voltage for the left tank increase? | 2 Hours | |||||||||||||
Did the fuel level sensor voltage for the right tank decrease? | -- | Go to Diagnostic Aids | ||||||||||||
Is the voltage at the specified voltage? | 0.0V | |||||||||||||
Is the voltage at the specified voltage? | 0.0V | |||||||||||||
|
Caution: Gasoline or gasoline vapors are highly flammable. A fire could occur if an ignition source is present. Never drain or store gasoline or diesel fuel in an open container, due to the possibility of fire or explosion. Have a dry chemical (Class B) fire extinguisher nearby.
Important: The scan tool will have to be commanded ON several times in order to achieve the time specified. Is the volume of fuel greater than the specified value? | 10 seconds 300 ml (0.633 pt) | |||||||||||||
20 |
Is the left fuel level sender voltage above the specified value? | 1.25V | ||||||||||||
21 | Drain the left fuel tank until the left fuel sender voltage is within the specified range. Refer to Fuel Tank Draining . Did you complete the action? | 1.0-1.25V | -- | |||||||||||
Important: The scan tool will have to be commanded ON several times in order to achieve the time specified. Is the volume of fuel greater than the specified value? | 8 seconds 332.6 ml (0.703 pt) | |||||||||||||
23 |
Did you find and correct the condition? | -- | ||||||||||||
24 | Replace the fuel Sender assembly that did not measure near the specified value. Refer to Fuel Sender Assembly Replacement . Is the action complete? | -- | -- | |||||||||||
25 | Repair the fuel lines between the fuel tanks for the following conditions:
Is the action complete? | -- | -- | |||||||||||
26 | Visually/physically inspect the fuel lines between the fuel tanks for the following conditions:
Did you find and correct the condition? | -- | ||||||||||||
27 | Replace the right tank fuel level sensor. Refer to Fuel Sender Assembly Replacement . Is the action complete? | -- | -- | |||||||||||
28 |
Did you find and correct the condition? | -- | ||||||||||||
29 |
Did you find and correct the condition? | -- | ||||||||||||
30 |
Did you find and correct the condition? | -- | ||||||||||||
31 |
Did you find and correct the condition? | -- | ||||||||||||
32 |
Important: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement . Is the action complete? | -- | -- | |||||||||||
33 | Replace the left tank fuel level sensor. Refer to Fuel Sender Assembly Replacement . Is the action complete? | -- | -- | |||||||||||
34 | Replace the right tank fuel level sensor. Refer to Fuel Sender Assembly Replacement . Is the action complete? | -- | -- | |||||||||||
Does the scan tool indicate that this test ran and passed? | -- | |||||||||||||
36 | Select the Capture Info option and the Review Info option using the scan tool. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
