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 less than 0.1 volt, DTC P0452 sets.
The following table illustrates the relationship between the 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 |
DTC Descriptor
This diagnostic procedure supports the following DTC:
P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage
Conditions for Running the DTC
DTC P0452 runs once per ignition cycle when the engine is running.
Conditions for Setting the DTC
| • | The FTP voltage is less than 0.1 volt. |
| • | The above condition is present for more than 15 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 MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | 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 emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
The rear body pass-through connector may be a convenient point for testing.
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 - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 | Observe the Fuel Tank Pressure Sensor parameter with a scan tool. Is the Fuel Tank Pressure Sensor parameter less than the specified value? | 0.1 V | Go to Step 4 | Go to Step 3 | ||||||
3 |
Is the Fuel Tank Pressure Sensor parameter less than the specified value? | 0.1 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 fuel tank pressure (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 13 | Go to Step 6 | ||||||
6 |
Is the voltage within the specified range? | 4.8-5.2 V | Go to Step 7 | Go to Step 8 | ||||||
7 |
Is the Fuel Tank Pressure Sensor parameter within the specified range? | 4.8-5.2 V | Go to Step 11 | Go to Step 9 | ||||||
8 | Test the FTP 5-volt 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 13 | Go to Step 10 | ||||||
9 | Test the FTP signal circuit for the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||||
10 | 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 13 | Go to Step 12 | ||||||
11 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
12 | Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 | ||||||
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | ||||||
