Circuit Description
The evaporative system includes the following components:
| • | The fuel tank |
| • | The EVAP vent solenoid |
| • | The fuel tank pressure sensor |
| • | The fuel pipes and the hoses |
| • | The fuel vapor lines |
| • | The fuel cap |
| • | The EVAP canister |
| • | The purge lines |
| • | The EVAP canister purge solenoid valve |
| • | The EVAP service port |
The evaporative emission system is tested by applying vacuum to the EVAP system and by monitoring for a vacuum decay. The powertrain control module (PCM) monitors the vacuum level through the fuel tank pressure sensor signal. At an appropriate time, the EVAP canister purge solenoid valve and the EVAP vent solenoid are turned ON, allowing the engine to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP canister purge solenoid valve is turned OFF, sealing the system.
The EVAP canister purge solenoid valve controls the amount of engine vacuum applied to the EVAP canister. The powertrain control module (PCM) supplies a ground in order to energize the solenoid valve (purge ON). The EVAP canister purge solenoid valve control is pulse width modulated (PWM) from 8 to 16 cycles per second. The duty cycle (pulse width) is determined by the engine operating conditions including the following items:
| • | Engine load |
| • | Throttle position |
| • | engine coolant temperature |
| • | Ambient temperature |
The system tests for conditions that cause the EVAP system to purge continuously by commanding the EVAP canister purge solenoid valve OFF. If the fuel tank vacuum level increases during the test, a continuous purge flow condition is indicated. This can be caused by the following conditions:
| • | A leak in the EVAP canister purge solenoid valve |
| • | The following lines may be switched at the EVAP canister purge solenoid valve: |
| - | EVAP purge |
| - | Engine vacuum |
| • | The EVAP canister purge solenoid valve driver circuit is grounded |
If any of these conditions are present, DTC P1441 will set.
Conditions for Running the DTC
| • | No active MAP DTCs |
| • | No active IAT DTCs |
| • | No active ECT DTCs |
| • | No active TP DTCs |
| • | No active oxygen sensor DTCs |
| • | No active fuel tank pressure sensor DTCs |
| • | No active VSS DTCs |
| • | No active PCM memory DTCs |
| • | The BARO is more than 75 kPa. |
| • | The intake air temperature is between 5°C and 29°C (41°F and 84°F) at engine start up. |
| • | The engine coolant temperature is between 5°C and 29°C (41°F and 84°F) at engine start up. |
| • | The intake air temperature is not more than 1°C (2°F) more than the engine coolant temperature at start up. |
| • | The engine coolant temperature is not more than 7°C (12°F) more than the intake air temperature at start up. |
| • | The fuel tank level is between 26 percent and 74 percent. |
| • | The TP sensor is between 7 percent and 35 percent. |
Conditions For Setting the DTC
The EVAP system is unable to detect vacuum during the diagnostic test.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. The Freeze Frame/Failure Records buffers will store this information. |
| • | The EVAP purge function is disabled until the diagnostic passes. |
| • | A history DTC stores. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs a pass. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a malfunction. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
Although this DTC is considered a type A diagnostic, the DTC acts like a type B diagnostic under certain conditions. Whenever this diagnostic reports the system has passed, or if the battery is disconnected, the diagnostic must fail twice before setting a DTC. The initial failure is not reported to the diagnostic executive or displayed on a scan tool. A passing system always reports to the diagnostic executive immediately.
Inspect for the following conditions:
| • | A poor connection at the PCM -- Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | A damaged harness -- Inspect the wiring harness for damage. If the harness appears to be OK, connect the EVAP pressure/purge cart to the EVAP service port, pressurize the EVAP system to 10 in. H2O and observe the Fuel Tank Vacuum Pressure display on the scan tool while moving the connectors and the wiring harnesses related to the EVAP canister purge valve. A sudden change in the display will indicate the location of the fault. |
| • | An incorrect vacuum line routing -- Verify that the source vacuum line routing to the EVAP canister purge valve is correct and that the EVAP purge and source vacuum lines to the EVAP canister purge valve are not switched. |
Inspect for charcoal particles. Refer to Evaporative Emission System Cleaning before starting repairs.
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
-
This step tests the fuel tank pressure sensor at the ambient pressure.
-
This step verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.
-
If the EVAP purge and engine vacuum lines are switched at the EVAP canister purge solenoid valve, the solenoid valve will leak vacuum.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
2 |
Is DTC P0452, P0453 or P0461 also set? | -- | ||||||||
3 |
Does the purge valve and vent solenoid click when command ON and OFF? | -- | ||||||||
Is the Fuel Tank Pressure within the specified value range? | -0.32 - +0.32 kPa (-1.28 - +1.28 in. H2O) | |||||||||
5 |
Did you find and correct the condition? | -- | Go to DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage or | |||||||
6 |
Important:: Before continuing with the diagnosis, zero the EVAP Pressure and Vacuum gauges on the J 41413 EVAP pressure/purge Diagnostic Station. Also read the temperature variation (refer to tool operating instructions).
Important: Do not exceed the pressure given in the specified value. Can the specified value be achieved? | 1.25 kPa (5 in H2O) | ||||||||
Is the Fuel Tank Pressure within the second specified value range? | 1.25 kPa (5 in. H2O) 1.25 kPa +/- 0.25 kPa (5 in. H2O +/- 1 in. H2O) | Go to DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage or | ||||||||
8 |
Does the EVAP canister purge solenoid valve maintain vacuum at the specified value? | 50.81 kPa (15 in. Hg) | ||||||||
Are the EVAP purge and source vacuum lines connected correctly at the EVAP canister purge solenoid valve? | -- | Go to Diagnostic Aids | ||||||||
10 |
Notice: The EVAP canister may have released carbon particles which caused this part to fail and may cause damage to other components. Check the EVAP canister for loose carbon before returning the vehicle to service. Did you complete the replacement? | -- | -- | |||||||
11 | Repair the EVAP purge and source vacuum line routing and connections. Did you complete the repair? | -- | -- | |||||||
12 |
Does the Fuel Tank Pressure remain at or above the specified value while the EVAP SEAL SYSTEM is ON? | 2,500 RPM 0 kPa (0 in. H2O) | ||||||||
13 |
Does the DTC reset? | -- | System OK |
