Circuit Description
The powertrain control module (PCM) monitors the fuel tank pressure sensor signal in order to detect vacuum decay and excess vacuum during the enhanced EVAP diagnostic. The fuel tank pressure sensor measures the difference between the air pressure (or vacuum) in the tank and the outside air pressure. The PCM applies a 5.0 volt reference and ground to the sensor. The sensor will return a signal voltage between 0.1 and 4.9 volts. If the PCM detects a fuel tank pressure sensor signal that is excessively low, DTC P0452 will set.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The fuel tank pressure sensor signal is less than 0.1 volts. |
| • | The condition is present for 5 seconds. |
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 the conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been run and passed. |
| • | 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 Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Continue the diagnosis at step 4 if you were sent here from one of the EVAP diagnostic tables.
Check for the following conditions:
| • | A faulty connection at the PCM or the fuel tank pressure sensor. Inspect the harness connectors for backed out terminals, improper mating broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections. Use a corresponding mating terminal to test for proper terminal tension. |
| • | Inspect the wiring harness for damage. If the harness appears to be OK, observe the Fuel Tank Pressure Sensor display on the scan tool while moving the connectors and the wiring related to the sensor. A change in the display will indicate the location of the malfunction. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 |
Important: If DTC P1635 5 Volt Reference Circuit is also set, perform that diagnostic first. Was the Powertrain On Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Is the voltage less than the specified value? | 0.3 V | ||
3 |
Important: Continue the diagnosis at step 4 if you were sent here from one of the EVAP diagnostic tables.
Does the scan tool indicate DTC P0452 failed this ign? | -- | Go to Diagnostic Aids | |
4 |
Is the voltage approximately equal to the specified value? | 5 V | ||
5 | Using a digital multimeter (DMM), measure the voltage between the 5 volt reference A circuit and the sensor ground circuit at the fuel tank pressure sensor harness connector. Is voltage approximately equal to the specified value? | 5 V | ||
6 |
Was a problem found? | -- | ||
7 |
Was a problem found? | -- | ||
8 |
Was a problem found? | -- | ||
9 |
Was a problem found? | -- | ||
10 |
Was a problem found? | -- | ||
11 | Replace the fuel tank pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the repair? | -- | -- | |
|
Important:: The replacement PCM must be programmed. . Replace the PCM. Refer to Powertrain Control Module Replacement/ProgrammingDid you complete the repair? | -- | -- | ||
13 |
Does the scan tool indicate DTC P0452 failed this ign? | -- | System OK |
