For 1990-2009 cars

Refer to Engine Controls Schematics

#### Engine Data Sensors

Engine Controls Components
Powertrain Control Module Description
Power, Ground, CMP, CKP 24X, CKP 7X, KS, and ICM
Cruise Control Module, and VSS
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Fuel System
.

### Circuit Description

The powertrain control module (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 low, DTC P0452 will set.

### Conditions for Running the DTC

• | The system voltage is between 10.0-18.0 volts.

• | The ignition is ON.

### Conditions for Setting the DTC

• | The fuel tank pressure sensor signal is less than 0.5 volts.

• | The condition 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

Continue the diagnosis at step 4 if you were sent here from one of the EVAP diagnostic tables.

Inspect for the following conditions:

Many situations may lead to an intermittent condition. Perform each inspection or test as directed.

Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

• | Loose terminal connection

- | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.

- | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.

• | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

• | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

#### DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On Board (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Important: If a 5-volt reference DTC sets go to that DTC first. Refer to DTC P1635 5 Volt Reference Circuit .

1. Turn ON the ignition, with the engine OFF.
2. Observe fuel tank pressure sensor voltage displayed on the scan tool.

Is the fuel tank pressure sensor voltage less than the specified value?

0.5V

Go to Step 4

Go to Step 3

3 | Important: Continue the diagnosis at step 4 if you were sent here from one of the EVAP diagnostic tables.

1. Review and record scan tool Failure Records data.
2. Clear the DTCs.
3. Operate the vehicle within Failure Records conditions.
4. Monitor Specific DTC info for DTC P0452.

Does the scan tool indicate DTC P0452 failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4 |

1. Disconnect the fuel tank pressure sensor electrical connector.
2. Connect a jumper between the fuel tank pressure signal circuit and the 5 Volt Reference A circuit at the fuel tank pressure sensor harness connector.
3. Observe fuel tank pressure sensor voltage displayed on the scan tool.

Is the fuel tank pressure sensor voltage near the specified value?

5.0V

Go to Step 8

Go to Step 5

5 | Using a DMM, measure the voltage between the 5 volt reference A circuit and the sensor ground circuit at the fuel tank pressure sensor harness connector. Is the voltage near the specified value? | 5.0V | Go to Step 9 | Go to Step 6
6 |

1. Turn OFF the ignition.
2. Disconnect the PCM.
3. Check the 5-volt Reference A circuit for a faulty terminal connection at the PCM.
4. If you find a problem, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 7

7 |

1. Check the 5-volt Reference A circuit between the fuel tank pressure sensor and the PCM for an open, a short to ground, or a short to the sensor ground circuit.
2. If you find a problem, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

8 |

1. Check for faulty terminal connections at the fuel tank pressure sensor connector.
2. If you find a problem, repair the connectors as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

9 |

1. Turn OFF the ignition.
2. Check the fuel tank pressure sensor signal circuit for a faulty terminal connection at the PCM.
3. If you find a problem, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

10 |

1. Check the fuel tank pressure signal circuit between the fuel tank pressure sensor connector and the PCM for an open, a short to ground, or a short to the sensor ground circuit.
2. If you find a problem, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

11 | Replace the fuel tank pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement . Is the action complete? | -- | Go to Step 13 | --
12 | Important : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 13 | --
13 |

1. Review and record scan tool Fail Records data.
2. Clear the DTCs.
3. Operate the vehicle within the Failure Records conditions.
4. Monitor the Specific DTC information for DTC P0452.

Does the scan tool indicate DTC P0452 failed this ignition?

--

Go to Step 2

System OK