Circuit Description
The powertrain control module (PCM) monitors the fuel tank pressure (FTP) sensor signal in order to detect vacuum decay and excess vacuum during the enhanced evaporative emission (EVAP) diagnostic. The PCM supplies a 5-volt reference and ground to the sensor. The FTP sensor signal voltage increases as the fuel tank pressure decreases, negative pressure or vacuum, high voltage. The FTP sensor signal voltage decreases as the fuel tank pressure increases, positive pressure, low voltage. When the FTP sensor signal voltage goes above a predetermined value, diagnostic trouble code (DTC) P0453 will set.
Conditions for Running the DTC
The key is ON.
Conditions for Setting the DTC
| • | The FTP sensor voltage is more than 4.9 volts. |
| • | All conditions present for greater than 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 ran 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 malfunction indicator lamp (MIL) will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool in order to clear the DTCs. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the signal circuit of the FTP sensor.
-
This step tests the ground circuit of the FTP sensor.
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This step tests the 5-volt reference circuit of the FTP sensor. If the DMM displays a voltage greater than 5 volts, repair the short to voltage.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Is the FTP sensor voltage above the specified value? | 4.3 V | Go to Step 4 | Go to Step 3 | |
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions |
Is the FTP sensor voltage less than the specified value? | 0.2 V | Go to Step 5 | Go to Step 7 | |
Probe the ground circuit of the FTP sensor with a test lamp connected to B+. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 8 | |
Measure the voltage from the FTP sensor 5-volt reference circuit with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage near the specified value? | 5 V | Go to Step 10 | Go to Step 11 | |
7 | Test the FTP sensor signal circuit for a short to voltage or a short to a 5-volt reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 |
8 | Test the ground circuit of the FTP sensor for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 9 |
9 | Inspect for poor connections at the harness connector of the PCM. 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 |
10 | Inspect for poor connections at the harness connector of 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 12 |
11 | Repair the 5-volt reference circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 14 | -- |
12 | Replace the FTP sensor. Refer to Throttle Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
13 | Replace the PCM. Refer to Powertrain Control Module Programming . Did you complete the replacement? | -- | Go to Step 14 | -- |
14 |
Does the DTC run and pass? | -- | Go to Step 15 | Go to Step 2 |
15 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
