Circuit Description
The fuel tank pressure sensor measures the pressure (or vacuum) in the fuel tank. The powertrain control module (PCM) provides the sensor with a reference voltage, a signal circuit, and a ground. The sensor returns a signal voltage to the PCM relative to the pressure in the fuel tank. The PCM should see a signal voltage increase as the pressure in the tank decreases (more vacuum). As the pressure in the tank increases (less vacuum), the PCM should see a signal voltage decrease. The PCM uses the sensor signal to test the integrity of the EVAP system. If the PCM detects a signal voltage that is too low, DTC P0452 will set.
Conditions for Running the DTC
The ignition is on.
Conditions for Setting the DTC
The fuel tank pressure sensor voltage is less than 0.1 volt for at least 1 second.
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data. |
| • | The PCM will disable the EVAP system. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Diagnostic Aids
If the condition is intermittent, refer to Intermittent Conditions in Symptoms.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines if the malfunction is present.
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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 help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine 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.
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If the scan tool displays 5.0 volts, the Fuel Tank Pressure sensor signal, 5.0 volt reference circuit, and the PCM are OK.
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If the scan tool displays 5.0 volts, the Fuel Tank Pressure sensor signal circuit and the PCM are OK.
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Disconnecting the PCM allows use of the DMM in order to test the continuity of the circuits. This aids in locating an open or a shorted circuit.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||||||||||
Did DTC P1639 fail this ignition cycle? | -- | |||||||||||
Monitor the Fuel Tank Pressure sensor voltage with the scan tool. Is the Fuel Tank Pressure sensor voltage below the specified value? | 0.10V | |||||||||||
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Go to Diagnostic Aids | ||||||||||
Is the Fuel Tank Pressure sensor voltage near the specified value? | 5.0V | |||||||||||
Is the Fuel Tank Pressure sensor voltage near the specified value? | 5.0V | |||||||||||
Did you find and repair the condition? | -- | |||||||||||
8 | Inspect the 5.0 volt reference circuit for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and repair the condition? | -- | ||||||||||
9 |
Did you find and repair the condition? | -- | ||||||||||
10 | Inspect the Fuel Tank Pressure sensor signal circuit for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and repair the condition? | -- | ||||||||||
11 | Inspect for a poor connection at the fuel tank jumper harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and repair the condition? | -- | ||||||||||
12 |
Is the Fuel Tank Pressure sensor voltage near the specified value? | 5.0V | ||||||||||
13 | Measure the Fuel Tank Pressure sensor 5.0 volt reference circuit between the Fuel Tank Pressure sensor connector and body ground with the DMM. Does the DMM display a voltage near the specified voltage? | 5.0V | ||||||||||
14 | Repair the open or grounded Fuel Tank Pressure sensor signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||
15 | Repair the open or grounded Fuel Tank Pressure sensor 5.0 volt reference circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||
16 | Inspect for a poor connection at the Fuel Tank Pressure sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and repair the condition? | -- | ||||||||||
17 | Replace the Fuel Tank Pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement . Is the action complete? | -- | -- | |||||||||
18 |
Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | |||||||||
19 | 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? | -- | ||||||||||
20 | Select the Capture Info option and the Review Info option with the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
