Circuit Description
The control module monitors the fuel tank pressure (FTP) sensor signal in order to detect vacuum decay and excess vacuum during the enhanced evaporative emissions (EVAP) diagnostic. The control module supplies a 5-volt reference and ground to the sensor. The FTP sensor signal voltage increases when the fuel tank pressure decreases, indicating a negative pressure or vacuum, or high voltage. The FTP sensor signal voltage decreases when the fuel tank pressure increases, indicating positive pressure, or low voltage. When the FTP sensor signal goes below a predetermined value, DTC P0452 will set.
DTC Descriptors
This diagnostic procedure supports the following DTC.
DTC P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage
Conditions for Running the DTC
| • | The engine is running. |
| • | DTC P0452 runs continuously. |
Conditions for Setting the DTC
| • | The fuel tank pressure sensor voltage is less than 0.1 volts. |
| • | All conditions are present for greater than 5 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the 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. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
2 |
Did DTC P0651 fail this ignition? | -- | Go to DTC P0651 | Go to Step 3 | ||||||
3 | With the scan tool, observe the fuel tank pressure (FTP) sensor voltage. Does the scan tool indicate that the FTP sensor voltage is less than the specified value? | 0.1 V | Go to Step 5 | Go to Step 4 | ||||||
4 |
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions | ||||||
Does the scan tool indicate that the FTP sensor voltage is near the specified value? | 5 V | Go to Step 8 | Go to Step 6 | |||||||
6 | Test the 5-volt reference circuit of the FTP sensor for an open between the body wiring harness connector and the PCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 7 | ||||||
7 | Test the signal circuit of the FTP sensor for a short to ground, or for an open between the body wiring harness connector and the PCM. 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 | ||||||
8 |
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 | ||||||
9 | Inspect for poor connections at the harness connector of the FTP sensor, and fuel tank harness body wiring harness connector 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 11 | ||||||
10 | Inspect for poor connections at the harness connector of the control module. 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 PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 | ||||||
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||
