Circuit Description
The fuel tank pressure (FTP) sensor measures the difference between the air pressure or vacuum in the Evaporative Emission (EVAP) System, and the outside air pressure. The engine control module (ECM) supplies the following circuits to the FTP sensor:
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | A signal circuit |
The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the ECM detects that the FTP sensor signal voltage is more than 4.9 volts, DTC P0453 sets.
The following table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.
FTP Sensor Signal Voltage | Fuel Tank Pressure |
|---|---|
Low, Approximately 1.5 Volts or Less | Positive Pressure |
High, Approximately 1.5 Volts or More | Negative Pressure/Vacuum |
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
| • | The FTP sensor voltage is more than 4.9 volts. |
| • | The condition is are present for more than 5 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 | Observe the Fuel Tank Pressure Sensor parameter with a scan tool. Is the Fuel Tank Pressure Sensor parameter more than the specified value? | 4.9 V | Go to Step 4 | Go to Step 3 |
3 |
Is the Fuel Tank Pressure Sensor parameter more than the specified value? | 4.9 V | Go to Step 4 | Go to Intermittent Conditions |
4 | Is DTC P0641 also set? | -- | Go to DTC P0641 | Go to Step 5 |
5 | Test for an intermittent and for a poor connection at the FTP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 6 |
6 | Observe the Fuel Tank Pressure Sensor parameter with a scan tool. Is Fuel Tank Pressure Sensor parameter more than the specified value? | 0.2 V | Go to Step 10 | Go to Step 7 |
7 |
Is the voltage less than the specified value? | 1.0 V | Go to Step 9 | Go to Step 8 |
8 | Test the low reference circuit of the FTP sensor for a short to voltage. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 9 |
9 | Test the FTP low reference circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 |
10 | Test the FTP signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 |
11 | Test for an intermittent and for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 |
12 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
13 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
14 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 15 |
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
