Dodge Ram Truck 1500-2500-3500. Manual — part 887

P0440-GENERAL EVAP SYSTEM FAILURE (CONTINUED)

For the Engine circuit diagram (Refer to 9 - ENGINE - SCHEMATICS AND DIAGRAMS).

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

The theory behind the Natural Vacuum Leak Detection (NVLD) is adherence to the Ideal Gas Law. Pressure in a
sealed vessel will change linearly as a function of the temperature of the gas in the vessel. Even small leaks will
allow the pressure in the vessel to come to equilibrium with the atmospheric pressure. After key-off and a calibrated
amount of time, cool down from operating temperatures or diurnal ambient temperature the system pressure will
force the system to go negative or draw a vacuum if there is no leak. When the vacuum level reaches 1” H2O (0.25
KPA) the NVLD vacuum switch closes. This sends a signal to the NGC freezing a timer and registering a pass. If
a switch closure is not detected an assessment of leak size will be made.

•

When Monitored:
Engine Running. Fuel Level greater than 12%. Ambient Temperature between 4°C and 32°C (39°F and 89°F).

•

Set Condition:
The PCM does not see the NVLD switch close during the medium/large leak test. The PCM then will increase
the vacuum supply to the EVAP system by increasing flow through the EVAP Purge valve. If the switch does
not close with an increase in vacuum an error is detected. Two Trip Fault. Three good trips to turn off the MIL.

Possible Causes

EVAP PURGE SOLENOID VACUUM SUPPLY

(Z910) GROUND CIRCUIT OPEN

(K107) NVLD SWITCH SIGNAL CIRCUIT OPEN

EVAPORATIVE EMISSION LEAK DETECTION

NVLD ASSEMBLY

EVAP PURGE SOLENOID

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).

Diagnostic Test

1.

ACTIVE DTC

NOTE: If any of the following DTCs are set (P0443, P0452, P0453, P0498 or P0499) diagnose them first
before continuing with P0440.
Ignition on, engine not running.

With a scan tool, read DTCs.

Is the DTC active at this time?

Yes

>> Go To 2

No

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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P0440-GENERAL EVAP SYSTEM FAILURE (CONTINUED)

2.

VISUAL AND PHYSICAL INSPECTION

Turn the ignition off.

Perform a visual and physical inspection of the entire Evaporative Emission system.

Check for the following conditions:

- Hoses disconnected or left off

- Holes or cracks

- Loose seal points

- Evidence of damaged components

- Incorrect routing of hoses and tubes

- Fuel Cap left off or bad gasket seal

Were any of the above conditions found?

Yes

>> Repair as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 3

3.

EVAP VACUUM SUPPLY HOSE INSPECTION

Carefully inspect the Evap Purge Solenoid vacuum supply hose for proper routing.

Check for a pinched or plugged hose from the throttle body to the Purge Solenoid.

Make sure the vacuum port at the throttle body is free from any blockage.

Were any problems found?

Yes

>> Repair the vacuum supply, hose/tube as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 4

4.

CHECKING EVAP PURGE SOLENOID FUNCTIONALITY

Disconnect the vacuum supply hoses form the EVAP Purge Solenoid.

Using a hand vacuum pump, apply 10 in Hg to the

9

CAN

9

side of the EVAP Purge Solenoid.

Ignition on, engine not running.

Observe the vacuum gauge.

With the scan tool, actuate the EVAP Purge Solenoid.

Does the vacuum drop when the solenoid is actuated?

Yes

>> Go To 5

No

>> Replace the Evap Purge Solenoid.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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P0440-GENERAL EVAP SYSTEM FAILURE (CONTINUED)

5.

NVLD SWITCH OPERATION

Connect the previously disconnected vacuum hose.

Start the engine.

Allow the engine to idle.

Using the scan tool, perform the NVLD FORCED MONITOR TEST.

Monitor the NVLD Switch state.

NOTE: As the test runs, the NVLD Switch should go from an OPEN state to a CLOSED state and then return
to OPEN when the test is complete.

Did the NVLD Switch operate as described above?

Yes

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 6

6.

VERIFY EVAPORATIVE EMISSION LEAK

To continue testing you will need Miller Tool #8404 Evaporative Emission Leak Detector (EELD).

WARNING: Keep lit cigarettes, sparks, flames, and other ignition sources away from the test area to prevent
the ignition of explosive gases. Keep the test area well ventilated.

NOTE: The fuel tank should have between 20% and 80% of fuel tank capacity to properly test the Evap
system.
Connect the red power lead of EELD to the battery positive terminal and the black ground lead to battery negative
terminal.

Block the vent hose of the EVAP Canister.

Connect shop air to the EELD.

Set the smoke/air control switch to AIR.

Insert the tester’s AIR supply tip (clear hose) into the .040 orifice on the tester’s control panel.

Press the remote smoke/air start button.

Position the red flag on the air flow meter so it is aligned with the indicator ball.

When the calibration is complete, release the remote button. The EELD flow meter is now calibrated in liters per
minute.

Install the service port adapter #8404-14 on the vehicle’s service port (if equipped) or install the #8404-ADP into the
filter line.

Connect the Air supply hose from the EELD to the service port (if equipped) or to the #8404-ADP adapter.

Press the remote button to activate AIR flow.

Compare the flow meter indicator ball reading to the red flag.

ABOVE the red flag indicates a leak present.

BELOW the red flag indicates a sealed system.

Is the indicator ball above the red flag?

Yes

>> Go To 7

No

>> Go To 8

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P0440-GENERAL EVAP SYSTEM FAILURE (CONTINUED)

7.

EVAPORATIVE EMISSION LEAK DETECTION

NOTE: A thorough visual inspection of the Evap system hoses, tubes, and connections may save time in
your diagnosis. Look for any physical damage or signs of wetness at connections. The strong smell of fuel
vapors may aid diagnosis also.
To continue testing, you will need Miller Tool #8404 Evaporative Emissions Leak Detector (EELD).

Remove the Air supply hose from the service port or the #8404-ADP adapter.

Connect the SMOKE supply tip (black hose) to the service port (if equipped) or to the #8404-ADP adapter.

Set the smoke/air control switch to SMOKE.

NOTE: The flow meter indicator ball will not move at this point.
Press the remote smoke/air start button.

NOTE: Make sure that smoke has filled the EVAP system by continuing to press the remote smoke/air start
button, remove the vehicle fuel cap, and wait for the smoke to exit. Once smoke is indicated reinstall the
fuel cap.

NOTE: For optimal performance, introduce smoke into the system for an additional 60 seconds; continue
introducing smoke at 15 second intervals, as necessary.
While still holding the remote smoke/air start button, use the white light (#8404-CLL) to follow the EVAP system
path, and look for the source of the leak indicated by exiting smoke.

If a leak is concealed from view (i.e., top of fuel tank), release the remote smoke/air start button, and use the ultra-
violet (UV) black light #8404-UVL and the yellow goggles 8404-20 to look for residual traces of dye that are left
behind by the smoke.

The exiting smoke deposits a residual fluid that is either bright green or bright yellow in color when viewed with a
UV light.

NOTE: Carefully inspect the vent side of the EVAP Canister. Due to the filtering system in the canister the
smoke or dye may or may not be visible. Introducing smoke into the filtered side of the canister may assist
in locating the leak.

Was a leak found?

Yes

>> Repair or replace the leaking component as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 11

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