GM Service Manual Online
For 1990-2009 cars only

DTC P1432 Without FFS

Circuit Description

The right fuel level sensor measures fuel level changes within the right fuel tank.

When the fuel level is high the sensor signal voltage is high. When the fuel level is low the sensor signal voltage is low.

The PCM uses inputs from the left fuel level sensor and the right fuel level sensor in order to calculate the total fuel remaining in both fuel tanks. The PCM sends this information via class 2 to the IPC.

This diagnostic tests for a stuck right fuel level sensor signal. If the PCM determines that the fuel level (right tank) signal appears to be stuck based on a lack of signal variation expected during normal operation, this DTC sets.

The left tank fuel pump also supplies a small amount of pressurized fuel to the right fuel tank siphon jet pump through the auxiliary fuel feed rear 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 auxiliary fuel return rear pipe. The fuel system is designed to maintain a greater level in the left fuel tank then 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 percent.

Conditions for Running the DTC

The engine is operating.

Conditions for Setting the DTC

    • The fuel level sensor voltage is below 0.39 volts.
    • The above conditions present for greater than 2.0 minutes.

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 vehicle fuel gage displays empty.
    • The check gage indicator illuminates.
    • The driver information center displays a message.

Conditions for Clearing the MIL or DTC

    • 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.
    • A last test failed, ore current DTC, will clear when the diagnostic runs and does not fail.
    • Use a scan tool in order to clear the MIL or DTC.

Diagnostic Aids

Important: When inspecting for a deformed or warped fuel tank, measure the resistance of the suspect fuel level sensor at empty, with the sensor in the fuel tank, and again with the sensor removed from the fuel tank. the resistance values should be the same empty. If the measured resistance values are not the same, refer to Fuel Tank Replacement in Engine Controls.

    • 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. Refer to Fuel Sender Assembly Replacement in Engine Controls in order to test the resistance of the sensor. The resistance of the sensor should change from 40 to 250 ohms. Replace the sensor if the resistance did not change or was out of range.
    • If the fuel level sensor is operating OK, test the operation of the Jet Pump.
    •  For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

The voltages in the Fuel Level Conversion Table are approximate values. Use this table to aid in diagnosis.

Test Description

The numbers below refer to the step numbers on the Diagnostic Table.

  1. This step determines if the fault is present.

Step

Action

Values

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the IPC Diagnostic System Check ?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

  1. Install the scan tool.
  2. Turn ON the ignition leaving the engine OFF.
  3. Monitor the Enhanced EVAP Fuel Level sensor right tank voltage on the scan tool.

Is the Fuel Level sensor voltage below the specified value?

0.39 V

Go to Step 4

Go to Step 3

3

  1. Turn ON the ignition leaving the engine OFF.
  2. Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
  3. Turn OFF the ignition for 15 seconds.
  4. Start the engine.
  5. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame and/or Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
  6. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Turn OFF the ignition.
  2. Disconnect the fuel level sensor right tank electrical connector. Refer to Fuel Sender Assembly Replacement in Engine Controls.
  3. Turn ON the ignition leaving the engine OFF.
  4. Observe the Fuel Level sensor voltage on the scan tool.

Is the Fuel Level sensor voltage below the specified value?

0.39 V

Go to Step 5

Go to Step 7

5

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C2 located on the opposite side of the manufacturers logo. Refer to Powertrain Control Module Replacement in Engine Controls.
  3. Test the Fuel Level sensor signal circuit for continuity to ground. Refer to Circuit Testing in Wiring Systems.

Is the Fuel Level sensor signal circuit grounded ?

--

Go to Step 6

Go to Step 8

6

Repair the grounded fuel level signal circuit between the PCM connector and the fuel level sensor. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 9

--

7

Replace the fuel level sensor. Refer to Fuel Sender Assembly Replacement in Engine Controls.

Did you complete the replacement?

--

Go to Step 9

--

8

Important: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls.

Did you complete the replacement?

--

Go to Step 9

--

9

  1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
  2. Start the engine and idle at the normal operating temperature.
  3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 10

Go to Step 2

10

Select the Capture Info option and the Review Info option using the scan tool.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to the applicable DTC

System OK

DTC P1432 W/FFS

Circuit Description

The right fuel level sensor measures fuel level changes within the right fuel tank and changes resistance based on fuel level. The powertrain control module (PCM) monitors 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 sensors to calculate the total fuel remaining in the fuel tanks. This information is then sent to the instrument panel cluster (IPC) via the class 2 serial data circuit.

When the PCM senses a signal voltage lower than the normal operating range of the sensor, this DTC sets.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

    • Fuel level sensor voltage for the right fuel level sensor is below 0.39 volts.
    • The fuel level signal is less than 3.5 percent.
    • The above conditions are present for greater than 2 minutes.

Action Taken When the DTC Sets

    • The DIC displays the LOW FUEL message.
    • The fuel gage defaults to empty.
    • The check gages indicator illuminates.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM displays the failure information in the Failure Records on the scan tool.

Conditions for Clearing the DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction free warm-up cycles.
    • The PCM receives the clear code command from the scan tool.

Diagnostic Aids

Important: When inspecting for a deformed or a warped fuel tank, measure the resistance of the suspect fuel level sensor at empty, with the sensor in the fuel tank, and again with the sensor removed from the fuel tank. The measured resistance values should be the same at empty. If the measured resistance values are not the same, refer to Fuel Tank Replacement in Engine Controls.

    • Use the Freeze Frame and/or Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data may aid in determining the number of miles since the DTC set.
    • The Fail Counter and Pass Counter can also aid in determining the number of ignition cycles that the diagnostic reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions (RPM, engine load, vehicle speed, temperature, etc.). This will isolate when the DTC failed.
        Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number below refers to the step number on the diagnostic table.

  1. Tests for the proper operation of the circuit in the high voltage range.

Step

Action

Value(s)

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the IPC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

  1. Install a scan tool.
  2. Turn the ignition ON , with the engine OFF.
  3. With a scan tool, observe the Fuel Tank Level Remaining parameter in the PCM Enhanced EVAP data list.

Does the scan tool indicate that the Fuel Level parameter is less than the specified value?

4%

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn the ignition OFF.
  2. Disconnect C402.
  3. Turn the ignition ON, with the engine OFF.
  4. With a scan tool, observe the Fuel Level parameter.

Does the scan tool indicate that the Fuel Tank Level Remaining parameter is greater than the specified value?

98%

Go to Step 5

Go to Step 4

4

Test the signal circuit of the fuel level sender for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

5

Test the signal circuit of the fuel level sensor for a short to ground between C402 and the fuel level sensor. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6

Inspect for poor connections at the harness connector of the fuel level sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8

Replace the fuel level sensor. Refer to Fuel Sender Assembly Replacement in Engine Controls.

Did you complete the replacement?

--

Go to Step 10

--

9

Important: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls.

Did you complete the replacement?

--

Go to Step 10

--

10

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

--

Go to Step 2

System OK