Refer to
Cell 21: Fuel Controls
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 high, DTC P0453 will set.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The fuel tank pressure sensor signal is greater than 4.7 volts. |
| • | The conditions 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 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
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
Number(s) below refer to the step number(s) on the Diagnostic Table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 | Is DTC P1639 also set? | -- | ||
3 |
Does the FTP indicate a voltage near the specified value? | 0V | ||
4 |
Was a problem found? | -- | ||
5 |
Is the test lamp ON? | -- | ||
6 |
Was a problem found? | -- | ||
7 |
Was a problem found? | -- | ||
8 |
Was a problem found? | -- | ||
9 |
Does the DMM display a voltage greater than the specified value? | 0V | ||
10 |
Does the DMM display a voltage greater than the specified value? | 0V | ||
11 | Locate and repair the short to voltage in the FTP sensor signal circuit. Refer to Wiring Repairs . Is the action complete? | -- | -- | |
12 |
Does the DMM display a voltage greater than the specified value? | 0V | ||
13 | Locate and repair the short to voltage in the A/C pressure sensor signal circuit. Refer to Wiring Repairs . Is the action complete? | -- | -- | |
14 | Locate and repair the short to voltage in the 5V reference B circuit. Refer to Wiring Repairs . Is the action complete? | -- | -- | |
|
Important: The replacement PCM must be reprogrammed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM Is the action complete? | -- | -- | ||
16 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Is the action complete? | -- | -- | |
17 |
Does the scan tool indicate that DTC P0453 has failed this ign? | -- | System OK |
