Evaporative Emissions Dodge Pickup R1500

DESCRIPTION - EVAP SYSTEM

The evaporation control system prevents the emission of fuel tank vapors into the atmosphere. When fuel evaporates in the fuel tank, the vapors pass through vent hoses or tubes into the two charcoal filled evaporative canisters. The canisters temporarily hold the vapors. The Powertrain Control Module (PCM) allows intake manifold vacuum to draw vapors into the combustion chambers during certain operating conditions.

All gasoline powered engines use a duty cycle purge system. The PCM controls vapor flow by operating the duty cycle EVAP purge solenoid. Refer to for additional information.

When equipped with certain emissions packages, a Leak Detection Pump (LDP) will be used as part of the evaporative system. This pump is used as a part of OBD II requirements. Refer to LEAK DETECTION PUMP . for additional information. Other emissions packages will use a Natural Vacuum Leak Detection (NVLD) system in place of the LDP. Refer to NVLD for additional information.

Note. The hoses used in this system are specially manufactured. If replacement becomes necessary, it is important to use only fuel resistant hose.

Certain EVAP system components can be found in (Scheme 1)

Scheme 1

TORQUE - EVAP SYSTEM

EVAP CANISTER MOUNTING SPECIFICATION

8.3L - SRT-10

The 8.3L V-10 engine is equipped with a Crankcase Ventilation (CCV) system. The CCV system performs the same function as a conventional PCV system, but use a fixed orifice instead of vacuum controlled valve (PCV valve).

It meters the amount of crankcase vapors drawn out of the engine. The fixed orifice fitting is mounted in each of the valve covers in the rear of the engine (Scheme 2)

When the engine is operating, fresh air enters the engine and mixes with crankcase vapors. Manifold vacuum draws the vapor/air mixture through the fixed orifice and into the intake manifold. The vapors are then consumed during engine combustion.

Scheme 2

Scheme 3

Scheme 4

Scheme 5

TESTING/CLEANING

The Crankcase Ventilation (CCV) system performs the same function as a conventional PCV system, but does not use a vacuum controlled valve. A vacuum fitting containing a fixed orifice of a calibrated size is used. It meters the amount of crankcase vapors drawn out of the engine.

1. Check each CCV system tube (line) for leaks, cracks, kinks or bends. Replace as necessary
2. Disconnect each CCV tube.
3. Blow compressed air through each tube and check for blockage or restrictions. If cleaning is necessary, spray a soapy-type all-purpose cleaner into each component and blow out. After restriction is cleared, rinse out component with clear water. Blow water from component and install to vehicle. To prevent damage to plastic components, never spray carburetor-type cleaner into any of the plastic tubes or the fixed orifice fitting. Never attempt to clean the fixed orifice fitting with a metal object as calibration could be affected. If fixed fitting cannot be cleared, replace it.

DESCRIPTION

The duty cycle EVAP canister purge solenoid is located in the engine compartment. It is attached to the side of the Power Distribution Center (PDC).

OPERATION

The Powertrain Control Module (PCM) operates the solenoid.

During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged. The PCM de-energizes the solenoid during open loop operation.

The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During closed loop operation, the PCM energizes and de-energizes the solenoid 5 or 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time the solenoid energizes. The PCM adjusts solenoid pulse width based on engine operating condition.

REMOVAL

The duty cycle EVAP canister purge solenoid is located in the engine compartment. It is attached to the side of the Power Distribution Center (PDC) (Scheme 6)

Scheme 6

1. Disconnect electrical wiring connector at solenoid.
2. Disconnect vacuum harness at solenoid (Scheme 6)
3. Remove solenoid from mounting bracket.

INSTALLATION

1. Install solenoid assembly to mounting bracket.
2. Connect vacuum harness.
3. Connect electrical connector.

The plastic fuel tank filler tube cap is threaded onto the end of the fuel fill tube. Certain models are equipped with a 1/4 turn cap.

The loss of any fuel or vapor out of fuel filler tube is prevented by the use of a pressure-vacuum fuel fill cap. Relief valves inside the cap will release fuel tank pressure at predetermined pressures. Fuel tank vacuum will also be released at predetermined values. This cap must be replaced by a similar unit if replacement is necessary. This is in order for the system to remain effective.

REMOVAL/INSTALLATION

If replacement of the 1/4 turn fuel tank filler tube cap is necessary, it must be replaced with an identical cap to be sure of correct system operation.

Vehicles equipped with JTEC engine control modules use a leak detection pump. Vehicles equipped with NGC engine control modules use an NVLD pump. Refer to NATURAL VACUUM LEAK DETECTION (NVLD) for additional information.

The evaporative emission system is designed to prevent the escape of fuel vapors from the fuel system (Scheme 7) Leaks in the system, even small ones, can allow fuel vapors to escape into the atmosphere, Government regulations require onboard testing to make sure that the evaporative (EVAP) system is functioning properly. The leak detection system tests for EVAP system leaks and blockage. It also performs self-diagnostics. During self-diagnostics, the Power-train Control Module (PCM) first checks the Leak Detection Pump (LDP) for electrical and mechanical faults. If the first checks pass, the PCM then uses the LDP to seal the vent valve and pump air into the system to pressurize it. If a leak is present, the PCM will continue pumping the LDP to replace the air that leaks out. The PCM determines the size of the leak based on how fast/long it must pump the LDP as it tries to maintain pressure in the system.

EVAP LEAK DETECTION SYSTEM COMPONENTS

Service Port: Used with special tools like the Miller Evaporative Emissions Leak Detector (EELD) to test for leaks in the system.

EVAP Purge Solenoid: The PCM uses the EVAP purge solenoid to control purging of excess fuel vapors stored in the EVAP canister. It remains closed during leak testing to prevent loss of pressure.

Scheme 7

EVAP Canister: The EVAP canister stores fuel vapors from the fuel tank for purging.

EVAP Purge Orifice: Limits purge volume.

EVAP System Air Filter: Provides air to the LDP for pressurizing the system. It filters out dirt while allowing a vent to atmosphere for the EVAP system.

The main purpose of the LDP is to pressurize the fuel system for leak checking. It closes the EVAP system vent to atmospheric pressure so the system can be pressurized for leak testing. The diaphragm is powered by engine vacuum. It pumps air into the EVAP system to develop a pressure of about 7.5" H2O (1/4) psi. A reed switch in the LDP allows the PCM to monitor the position of the LDP diaphragm. The PCM uses the reed switch input to monitor how fast the LDP is pumping air into the EVAP system.

This allows detection of leaks and blockage. The LDP assembly consists of several parts (Scheme 8) The solenoid is controlled by the PCM, and it connects the upper pump cavity to either engine vacuum or atmospheric pressure. A vent valve closes the EVAP system to atmosphere, sealing the system during leak testing. The pump section of the LDP consists of a diaphragm that moves up and down to bring air in through the air filter and inlet check valve, and pump it out through an outlet check valve into the EVAP system. The diaphragm is pulled up by engine vacuum, and pushed down by spring pressure, as the LDP solenoid turns on and off. The LDP also has a magnetic reed switch to signal diaphragm position to the PCM. When the diaphragm is down, the switch is closed, which sends a 12 V (system voltage) signal to the PCM. When the diaphragm is up, the switch is open, and there is no voltage sent to the PCM. This allows the PCM to monitor LDP pumping action as it turns the LDP solenoid on and off.

Scheme 8

LDP AT REST (NOT POWERED)

When the LDP is at rest (no electrical/vacuum) the diaphragm is allowed to drop down if the internal (EVAP system) pressure is not greater than the return spring. The LDP solenoid blocks the engine vacuum port and opens the atmospheric pressure port connected through the EVAP system air filter. The vent valve is held open by the diaphragm. This allows the canister to see atmospheric pressure (Scheme 9)

Scheme 9

DIAPHRAGM UPWARD MOVEMENT

When the PCM energizes the LDP solenoid, the solenoid blocks the atmospheric port leading through the EVAP air filter and at the same time opens the engine vacuum port to the pump cavity above the diaphragm. The diaphragm moves upward when vacuum above the diaphragm exceeds spring force. This upward movement closes the vent valve. It also causes low pressure below the diaphragm, unseating the inlet check valve and allowing air in from the EVAP air filter. When the diaphragm completes its upward movement, the LDP reed switch turns from closed to open (Scheme 10)

Scheme 10

DIAPHRAGM DOWNWARD MOVEMENT

Based on reed switch input, the PCM de-energizes the LDP solenoid, causing it to block the vacuum port, and open the atmospheric port. This connects the upper pump cavity to atmosphere through the EVAP air filter. The spring is now able to push the diaphragm down. The downward movement of the diaphragm closes the inlet check valve and opens the outlet check valve pumping air into the evaporative system. The LDP reed switch turns from open to closed, allowing the PCM to monitor LDP pumping (diaphragm up/down) activity (Scheme 11) During the pumping mode, the diaphragm will not move down far enough to open the vent valve. The pumping cycle is repeated as the solenoid is turned on and off. When the evaporative system begins to pressurize, the pressure on the bottom of the diaphragm will begin to oppose the spring pressure, slowing the pumping action. The PCM watches the time from when the solenoid is de-energized, until the diaphragm drops down far enough for the reed switch to change from opened to closed. If the reed switch changes too quickly, a leak may be indicated. The longer it takes the reed switch to change state, the tighter the evaporative system is sealed. If the system pressurizes too quickly, a restriction somewhere in the EVAP system may be indicated.

Scheme 11

PUMPING ACTION

Action: During portions of this test, the PCM uses the reed switch to monitor diaphragm movement. The solenoid is only turned on by the PCM after the reed switch changes from open to closed, indicating that the diaphragm has moved down. At other times during the test, the PCM will rapidly cycle the LDP solenoid on and off to quickly pressurize the system. During rapid cycling, the diaphragm will not move enough to change the reed switch state. In the state of rapid cycling, the PCM will use a fixed time interval to cycle the solenoid. If the system does not pass the EVAP Leak Detection Test, the following DTCs may be set

1. P0442 - EVAP LEAK MONITOR 0.040" LEAK DETECTED
2. P0455 - EVAP LEAK MONITOR LARGE LEAK DETECTED
3. P0456 - EVAP LEAK MONITOR 0.020" LEAK DETECTED
4. P1486 - EVAP LEAK MON PINCHED HOSE FOUND
5. P1494 - LEAK DETECTION PUMP SW OR MECH FAULT
6. P1495 - LEAK DETECTION PUMP SOLENOID CIRCUIT

The Leak Detection Pump (LDP) and LDP filter are attached to the front of the EVAP canister mounting bracket (Scheme 12) This is located near the front of the fuel tank. The LDP and LDP filter are replaced (serviced) as one unit.

Scheme 12

1. Raise and support vehicle.
2. Carefully remove hose at LDP filter.
3. Remove LDP filter mounting bolt and remove from vehicle.
4. Carefully remove vapor/vacuum lines at LDP.
5. Disconnect electrical connector at LDP.
6. Remove LDP mounting bolt and remove LDP from vehicle.

The LDP and LDP filter are attached to the front of the EVAP canister mounting bracket. The LDP and LDP filter are replaced (serviced) as one unit.

1. Install LDP to mounting bracket. Refer to «SPECIFICATIONS»(/dodge/pickup-r1500/1997-2012/remont/auxiliary-emission-control-systems/#evaporative-emissions) .
2. Install LDP filter to mounting bracket. Refer to «SPECIFICATIONS»(/dodge/pickup-r1500/1997-2012/remont/auxiliary-emission-control-systems/#evaporative-emissions) .
3. Carefully install vapor/vacuum lines to LDP, and install hose to LDP filter. The vapor/vacuum lines and hoses must be firmly connected. Check the vapor/vacuum lines at the LDP, LDP filter and EVAP canister purge solenoid for damage or leaks. If a leak is present, a Diagnostic Trouble Code (DTC) may be set.
4. Connect electrical connector to LDP.

The ORVR (On-Board Refueling Vapor Recovery) system consists of a unique fuel tank, flow management valve, fluid control valve, one-way check valve and vapor canister.

The ORVR (On-Board Refueling Vapor Recovery) system is used to remove excess fuel tank vapors. This is done while the vehicle is being refueled.

Fuel flowing into the fuel filler tube (approx. 1" I.D.) creates an aspiration effect drawing air into the fuel fill tube. During refueling, the fuel tank is vented to the EVAP canister to capture escaping vapors. With air flowing into the filler tube, there are no fuel vapors escaping to the atmosphere. Once the refueling vapors are captured by the EVAP canister, the vehicle's computer controlled purge system draws vapor out of the canister for the engine to burn. The vapor flow is metered by the purge solenoid so that there is no, or minimal impact on driveability or tailpipe emissions.

As fuel starts to flow through the fuel fill tube, it opens the normally closed check valve and enters the fuel tank. Vapor or air is expelled from the tank through the control valve and on to the vapor canister. Vapor is absorbed in the EVAP canister until vapor flow in the lines stops. This stoppage occurs following fuel shut-off, or by having the fuel level in the tank rise high enough to close the control valve. This control valve contains a float that rises to seal the large diameter vent path to the EVAP canister. At this point in the refueling process, fuel tank pressure increases, the check valve closes (preventing liquid fuel from spiting back at the operator), and fuel then rises up the fuel filler tube to shut off the dispensing nozzle.

3.7L V-6 / 4.7L V-8

The 3.7L V-6 and 4.7L V-8 engines are equipped with a closed crankcase ventilation system and a Positive Crankcase Ventilation (PCV) valve.

This system consists of

Scheme 13

1. a PCV valve mounted to the oil filler housing (Scheme 13) The PCV valve is sealed to the oil filler housing with an o-ring.
2. the air cleaner housing
3. two interconnected breathers threaded into the rear of each cylinder head (Scheme 14)
4. tubes and hoses to connect the system components.

5.7L V-8

The 5.7L V-8 engine is equipped with a closed crankcase ventilation system and a Positive Crankcase Ventilation (PCV) valve.

This system consists of

Scheme 14

Scheme 15

1. a PCV valve mounted into the top of the intake manifold, located to the right / rear of the throttle body (Scheme 15) The PCV valve is sealed to the intake manifold with 2 o-rings (Scheme 16)
2. passages in the intake manifold.
3. tubes and hoses to connect the system compnents.

5.9L V-8

The 5.9L V-8 engine is equipped with a closed crankcase ventilation system and a positive crankcase ventilation (PCV) valve.

This system consists of a PCV valve mounted on the cylinder head (valve) cover with a hose extending from the valve to the intake manifold (Scheme 17) Another hose connects the opposite cylinder head (valve) cover to the air cleaner housing to provide a source of clean air for the system. A separate crankcase breather/filter is not used.

Scheme 16

Scheme 17

The PCV system operates by engine intake manifold vacuum (Scheme 18) Filtered air is routed into the crankcase through the air cleaner hose. The metered air, along with crankcase vapors, are drawn through the PCV valve and into a passage in the intake manifold. The PCV system manages crankcase pressure and meters blow by gases to the intake system, reducing engine sludge formation.

Scheme 18

The PCV valve contains a spring loaded plunger. This plunger meters the amount of crankcase vapors routed into the combustion chamber based on intake manifold vacuum.

When the engine is not operating or during an engine pop-back, the spring forces the plunger back against the seat (Scheme 19) This will prevent vapors from flowing through the valve.

Scheme 19

During periods of high manifold vacuum, such as idle or cruising speeds, vacuum is sufficient to completely compress spring. It will then pull the plunger to the top of the valve (Scheme 20) In this position there is minimal vapor flow through the valve.

Scheme 20

During periods of moderate manifold vacuum, the plunger is only pulled part way back from inlet. This results in maximum vapor flow through the valve (Scheme 21)

Scheme 21

DIAGNOSIS AND TESTING - PCV VALVE - 3.7L V-6 / 4.7L V-8

1. Disconnect PCV line/hose (Scheme 22) by disconnecting rubber connecting hose at PCV valve fitting.
2. Remove PCV valve at oil filler tube by rotating PCV valve downward until locating tabs have been freed at cam lock (Scheme 22) After tabs have cleared, pull valve straight out from filler tube. To prevent damage to PCV valve locating tabs, valve must be pointed downward for removal. Do not force valve from oil filler tube.
3. After valve is removed, check condition of valve o-ring (Scheme 22) Also, PCV valve should rattle when shaken.
4. Reconnect PCV valve to its connecting line/hose.
5. Start engine and bring to idle speed.
6. If valve is not plugged, a hissing noise will be heard as air passes through valve. Also, a strong vacuum should be felt with a finger placed at valve inlet.
7. If vacuum is not felt at valve inlet, check line/hose for kinks or for obstruction. If necessary, clean out intake manifold fitting at rear of manifold. Do this by turning a 1/4 inch drill (by hand) through the fitting to dislodge any solid particles. Blow out the fitting with shop air. If necessary, use a smaller drill to avoid removing any metal from the fitting.
8. Do not attempt to clean the old PCV valve.
9. Return PCV valve back to oil filler tube by placing valve locating tabs (Scheme 22) into cam lock. Press PCV valve in and rotate valve upward. A slight click will be felt when tabs have engaged cam lock. Valve should be pointed towards rear of vehicle.
10. Connect PCV line/hose and connecting rubber hose to PCV valve.
11. Disconnect rubber hose from fresh air fitting at air cleaner resonator box. Start engine and bring to idle speed. Hold a piece of stiff paper (such as a parts tag) loosely over the opening of the disconnected rubber hose.
12. The paper should be drawn against the hose opening with noticeable force. This will be after allowing approximately one minute for crankcase pressure to reduce.
13. If vacuum is not present, disconnect each PCV system hose at top of each crankcase breather (Scheme 23) Check for obstructions or restrictions.
14. If vacuum is still not present, remove each PCV system crankcase breather (Scheme 23) from each cylinder head. Check for obstructions or restrictions. If plugged, replace breather. Tighten breather to 12 N.m (106 in. lbs.) torque. Do not attempt to clean breather.
15. If vacuum is still not present, disconnect each PCV system hose at each fitting, and at each check valve (Scheme 24) Check for obstructions or restrictions.

The PCV valve is located on the oil filler tube (Scheme 25) Two locating tabs are located on the side of the valve (Scheme 25) These 2 tabs fit into a cam lock in the oil filler tube. An o-ring seals the valve to the filler tube.

1. Disconnect PCV line/hose (Scheme 25) by disconnecting rubber hose at PCV valve fitting.
2. Remove PCV valve at oil filler tube by rotating PCV valve downward (counter-clockwise) until locating tabs have been freed at cam lock (Scheme 25) After tabs have cleared, pull valve straight out from filler tube. To prevent damage to PCV valve locating tabs, valve must be pointed downward for removal. Do not force valve from oil filler tube.
3. After valve is removed, check condition of valve o-ring (Scheme 25)

The PCV valve is mounted into the top of the intake manifold, located to the right / rear of the throttle body (Scheme 15) The PCV valve is sealed to the intake manifold with 2 o-rings (Scheme 16)

Scheme 22

Scheme 23

Scheme 24

1. Remove PCV valve by rotating counter-clockwise 90 degrees until locating tabs have been freed. After tabs have cleared, pull valve straight up from intake manifold.
2. After valve is removed, check condition of 2 valve o-rings.

3.7L V6 / 4.7L V-8

The PCV valve is located on the oil filler tube. Two locating tabs are located on the side of the valve. These 2 tabs fit into a cam lock in the oil filler tube. An o-ring seals the valve to the filler tube.

1. Return PCV valve back to oil filler tube by placing valve locating tabs into cam lock. Press PCV valve in and rotate valve upward. A slight click will be felt when tabs have engaged cam lock. Valve should be pointed towards rear of vehicle.
2. Connect PCV line/hose and rubber hose to PCV valve.

Scheme 25

1. Clean out intake manifold opening.
2. Check condition of 2 o-rings on PCV valve.
3. Apply engine oil to 2 o-rings.
4. Place PCV valve into intake manifold and rotate 90 degrees clockwise for installation.

A vacuum schematic for emission related items can be found on the vehicles Vehicle Emission Control Information (VECI) Label.

Two, maintenance free, EVAP canisters are used. Both canisters are mounted into a two-piece support bracket located near the front of the fuel tank (Scheme 26)

Scheme 26

Two, maintenance free, EVAP canisters are used.The EVAP canisters are filled with granules of an activated carbon mixture. Fuel vapors entering the EVAP canisters are absorbed by the charcoal granules.

Fuel tank pressure vents into the EVAP canisters. Fuel vapors are temporarily held in the canisters until they can be drawn into the intake manifold. The duty cycle EVAP canister purge solenoid allows the EVAP canisters to be purged at predetermined times and at certain engine operating conditions.

Two, maintenance free, EVAP canisters are used. Both canisters are mounted into a two-piece support bracket located near the front of the fuel tank (Scheme 26)

Scheme 27

1. Raise and support vehicle.
2. Remove fuel tubes/lines at each EVAP canister. Note location of tubes/lines before removal for easier installation.
3. Remove lower support bracket (Scheme 27)
4. Remove mounting nuts at top of each canister (Scheme 27)
5. Remove each canister from upper support bracket.

1. Place each canister into upper support bracket and install nuts. Refer to «SPECIFICATIONS»(/dodge/pickup-r1500/1997-2012/remont/auxiliary-emission-control-systems/#evaporative-emissions) .
2. Install lower support bracket. Refer to «SPECIFICATIONS»(/dodge/pickup-r1500/1997-2012/remont/auxiliary-emission-control-systems/#evaporative-emissions) .
3. Carefully install vapor/vacuum lines. The vapor/vacuum lines and hoses must be firmly connected. Also check the vapor/vacuum lines at the LDP, LDP filter and EVAP canister purge solenoid for damage or leaks. If a leak is present, a Diagnostic Trouble Code (DTC) may be set.

Vehicles equipped with NGC engine control modules use an NVLD pump and system.Vehicles equipped with JTEC engine control modules use an LDP (leak detection pump). Refer to LEAK DETECTION PUMP . (LDP) for additional information.

The NVLD pump is located in the same area as the leak detection pump. Refer to REMOVAL for additional information.

Vehicles equipped with NGC engine control modules use an NVLD pump and system.Vehicles equipped with JTEC engine control modules use a leak detection pump. Refer to LEAK DETECTION PUMP , (LDP) for additional information.

The Natural Vacuum Leak Detection (NVLD) system is the next generation evaporative leak detection system that will first be used on vehicles equipped with the Next Generation Controller (NGC). This new system replaces the leak detection pump as the method of evaporative system leak detection. This is to detect a leak equivalent to a 0.020" (0.5 mm) hole. This system has the capability to detect holes of this size very dependably.

The basic leak detection theory employed with NVLD is the "Gas Law". This is to say that the pressure in a sealed vessel will change if the temperature of the gas in the vessel changes. The vessel will only see this effect if it is indeed sealed -->. Even small leaks will allow the pressure in the vessel to come to equilibrium with the ambient pressure. In addition to the detection of very small leaks, this system has the capability of detecting medium as well as large evaporative system leaks.

A vent valve seals the canister vent during engine off conditions. If the vapor system has a leak of less than the failure threshold, the evaporative system will be pulled into a vacuum, either due to the cool down from operating temperature or diurnal ambient temperature cycling. The diurnal effect is considered one of the primary contributors to the leak determination by this diagnostic. When the vacuum in the system exceeds about 1" H2O (0.25 KPA), a vacuum switch closes. The switch closure sends a signal to the NGC. The NGC, via appropriate logic strategies, utilizes the switch signal, or lack thereof, to make a determination of whether a leak is present.

The NVLD device is designed with a normally open vacuum switch, a normally closed solenoid, and a seal, which is actuated by both the solenoid and a diaphragm. The NVLD is located on the atmospheric vent side of the canister. The NVLD assembly may be mounted on top of the canister outlet, or in-line between the canister and atmospheric vent filter. The normally open vacuum switch will close with about 1" H2O (0.25 KPA) vacuum in the evaporative system. The diaphragm actuates the switch. This is above the opening point of the fuel inlet check valve in the fill tube so cap off leaks can be detected. Submerged fill systems must have recirculation lines that do not have the in-line normally closed check valve that protects the system from failed nozzle liquid ingestion, in order to detect cap off conditions.

The normally closed valve in the NVLD is intended to maintain the seal on the evaporative system during the engine off condition. If vacuum in the evaporative system exceeds 3" to 6" H2O (0.75 to 1.5 KPA), the valve will be pulled off the seat, opening the seal. This will protect the system from excessive vacuum as well as allowing sufficient purge flow in the event that the solenoid was to become inoperative.

The solenoid actuates the valve to unseal the canister vent while the engine is running. It also will be used to close the vent during the medium and large leak tests and during the purge flow check. This solenoid requires initial 1.5 amps of current to pull the valve open but after 100 ms. will be duty cycled down to an average of about 150 mA for the remainder of the drive cycle.

Another feature in the device is a diaphragm that will open the seal in the NVLD with pressure in the evaporative system. The device will "blow off" at about 0.5" H2O (0.12 KPA) pressure to permit the venting of vapors during refueling. An added benefit to this is that it will also allow the tank to "breathe" during increasing temperatures, thus limiting the pressure in the tank to this low level. This is beneficial because the induced vacuum during a subsequent declining temperature will achieve the switch closed (pass threshold) sooner than if the tank had to decay from a built up pressure.

The device itself has 3 wires: Switch sense, solenoid driver and ground. It also includes a resistor to protect the switch from a short to battery or a short to ground. The NGC utilizes a high-side driver to energize and duty-cycle the solenoid.

The NVLD pump and filter are attached to the front of the EVAP canister mounting bracket (Scheme 28) This is located near the front of the fuel tank. The pump and filter are replaced (serviced) as one unit.

Scheme 28

Scheme 29

1. Raise and support vehicle.
2. Carefully remove pump hose clamp and hose at filter.
3. Carefully remove other vapor/vacuum hose at pump.
4. Disconnect 3-way electrical connector at pump.
5. The NVLD pump snaps onto the EVAP canister mounting bracket. Press on release tab (Scheme 29) while sliding pump from bracket.

1. Install NVLD pump to EVAP canister mounting bracket (snaps on).
2. Install NVLD filter and bolt to EVAP canister mounting bracket. Refer to «SPECIFICATIONS»(/dodge/pickup-r1500/1997-2012/remont/auxiliary-emission-control-systems/#evaporative-emissions) .
3. Carefully install vapor/vacuum lines to NVLD pump, and install hose to filter. The vapor/vacuum lines and hoses must be firmly connected. Check the vapor/vacuum lines at the NVLD pump, filter and EVAP canister purge solenoid for damage or leaks. If a leak is present, a Diagnostic Trouble Code (DTC) may be set.
4. Connect 3-way electrical connector to pump.

See also:
• LEAK DETECTION PUMP