Refer to Engine Controls Schematic
.
Circuit Description
The PCM monitors the fuel tank pressure sensor signal 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
| • | System voltage between 10 and 18 volts |
| • | The ignition is on. |
Conditions for Setting the DTC
| • | The fuel tank pressure sensor signal is less than 0.5 volts. |
| • | The conditions is present for 5 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/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has 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 a scan tool. |
Diagnostic Aids
Continue the diagnosis at step 4 if you were sent here from one of the EVAP diagnostic tables.
Check for the following condition(s):
| • | Poor connection at the PCM or Fuel Tank Pressure Sensor. |
| Inspect harness connectors for backed out terminals, improper mating broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. |
| 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 connectors and wiring related to the sensor. A change in the display will indicate the location of the malfunction. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Important: If a 5 volt reference DTC sets go to that DTC first. Refer to DTC P1639 5 Volt Reference 2 Circuit .
Is the fuel tank pressure sensor 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 ignition? | -- | Go to Diagnostic Aids | |
4 |
Is the fuel tank pressure sensor voltage near the specified value? | 5.0 V | ||
5 | Using a DMM, measure voltage between the 5 volt reference A circuit and the sensor ground circuit at the fuel tank pressure sensor harness connector. Is the voltage near the specified value? | 5.0 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 Is the action complete? | -- | -- | |
|
Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
13 |
Does the scan tool indicate DTC P0452 failed this ignition? | -- | System OK |
