Emissions Control: Overview Dodge Challenger III facelift

OPERATION

The switch inputs to the Powertrain Control Module (PCM) have two recognized states; HIGH and LOW. For this reason, the PCM cannot recognize the difference between a selected switch position versus an open circuit, a short circuit, or a defective switch. If the State Display screen shows the change from HIGH to LOW or LOW to HIGH, assume the entire switch circuit to the PCM functions properly. From the state display screen, access either State Display Inputs, Outputs or State Display Sensors.

Scheme 1

The evaporative emissions system is designed to control the release of fuel vapors into the atmosphere. The fuel tank check valve (4) and control valve (5) are used to reduce emissions due to the venting of vapor expansion within the fuel tank. When fuel evaporates from the fuel tank, vapors pass through a vent hose to the evaporative charcoal canister (3) where they are temporarily held. When the engine is running, the vapors are drawn into the intake manifold (8). In addition, fuel vapors produced during vehicle refueling are allowed to pass through the vent hose to the evaporative charcoal canister (3) for temporary storage (prior to being drawn into the intake manifold). The fuel tank check valve (4) and control valve (5) are non-serviceable components of the fuel tank assembly. The system is equipped with self-diagnosing capability using an Evaporative System Integrity Monitor (2). Refer to SWITCH, EVAPORATIVE EMISSIONS SYSTEM MONITOR, OPERATION .

The fuel tank pressure sensor (7) provides the PCM with information on vapor pressure inside the fuel tank. Excessive fuel tank pressure could cause fuel vapors to vent out the fuel filler cap or damage system components while insufficient fuel tank pressure (vacuum) caused by lack of fresh air entering the tank (1) to take the place of consumed fuel could lead to collapsed tank, lines or loss of fuel pressure.

The inlet check valve (6) prevents fuel from splashing back on the customer during vehicle refueling. This valve is also a non-serviceable component of the fuel tank assembly.

Scheme 2

Scheme 3

Scheme 4

Scheme 5

1. Disconnect the negative battery cable.
2. Remove the fuel tank filler cap.
3. Raise and support the vehicle.
4. Remove the right rear tire.
5. Remove the right rear wheelhouse splash shield.
6. Disconnect the ESIM electrical connector (1).
7. Disconnect the fuel tank vapor line (2) quick-connect fitting from the EVAP canister and position aside.
8. Disconnect the vapor purge line (3) quick-connect fitting from the EVAP canister and position aside.
9. Remove the vapor canister retaining nut (1).
10. Lower the front of the vapor canister.
11. Slide the vapor canister forward off of rear mounting brackets.
12. Make sure you do not lose the rear mounting bracket rubber mounts.
13. Remove the vapor canister, ESIM, and fresh air filter from the vehicle as an assembly.

DESCRIPTION

The plastic fuel fill cap is a threaded with 1/4 turn onto the end of the fuel filler tube. Its purpose is to retain vapors and fuel in the fuel tank.

The loss of any fuel vapor out of fuel filler tube is prevented by the use of 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 for the system to remain effective.

Scheme 6

The fuel tank pressure sensor provides the PCM with information on vapor pressure inside the fuel tank. The sensor is a diaphragm-type pressure sensor and varies its voltage output depending on fuel tank pressure. When the fuel tank isolation valve is activated (closed), preventing fuel vapors from leaving the tank, the PCM will monitor the fuel tank pressure sensor to prevent pressure from increasing or decreasing to an unsafe level.

Excessive fuel tank pressure could cause fuel vapors to vent out the fuel filler cap or damage system components while insufficient fuel tank pressure (vacuum) caused by lack of air entering the tank to take the place of consumed fuel could lead to collapsed tank, lines or loss of fuel pressure.

Scheme 7

Scheme 8

Scheme 9

1. Disconnect and isolate the negative battery cable (1).
2. Partially raise and the support vehicle.
3. Remove the left rear tire.
4. Remove the push-pins (1) that secure the rear wheelhouse splash shield (2) to the body.
5. Remove the rear wheelhouse splash shield from the vehicle.
6. Disconnect the fuel tank pressure sensor electrical connector (1).
7. Disconnect the fuel tank vent line at the filler tube (3) and the fuel tank vent steel line (6).
8. Carefully raise the retaining tab (2), rotate and remove the fuel tank pressure sensor (1) from the fuel tank vent tube.

Scheme 10

Scheme 11

1. The fuel tank pressure sensor seal (1) can be reused if not damaged.
2. Install the fuel tank pressure sensor (1) into the fuel tank vent tube and rotate until it locks into position.
3. Connect the fuel filler tube vent line (3) at the filler tube (4) and the fuel tank vent steel line (6).
4. Connect the fuel pressure electrical connector (1).
5. Position the rear wheelhouse splash shield (2) to the body and install the push-pins (1).
6. Install the left rear tire.
7. Lower the vehicle.
8. Connect the negative battery cable (1).

Scheme 12

The EVAP purge solenoid (1) attaches to a bracket near the right rear of the engine. The solenoid will not operate unless it is installed correctly.

1. Disconnect the electrical connector (2) from the EVAP purge solenoid.
2. Disconnect the vacuum lines (3, 5) from the EVAP purge solenoid.
3. Remove the EVAP purge solenoid (1) from the mounting bracket.

Scheme 13

Note. 6.4L engine shown in illustration, 5.7L engine is similar.

The EVAP purge solenoid attaches to a bracket near the right rear of the engine. The solenoid will not operate unless it is installed correctly.

1. Disconnect the electrical connector (1) from the EVAP purge solenoid.
2. Disconnect the vacuum lines (2) from the EVAP purge solenoid.
3. Remove the EVAP purge solenoid (3) from the bracket.

The following procedure has been established to assist technicians in the field with enabling and running OBD II monitors. The order listed in the following procedure is intended to allow the technician to effectively complete each monitor and to set the California Air Resources Board (CARB) Readiness Status in the least time possible.

Note. Once the monitor run process has started, do not turn off the ignition. By turning the ignition key off, monitor enabling conditions will be lost. The EVAP monitor runs after key off. By performing a battery disconnect, or selecting erase DTCs, the CARB Readiness and all additional OBD II information will be cleared.

The PCM with Powertrain Control Module (PCM) is responsible for efficiently coordinating the operation of all the emissions-related components. The PCM is also responsible for determining if the diagnostic systems are operating properly. The software designed to carry out these responsibilities is called the task manager.

The Task Manager determines when tests happen and when functions occur. Many of the diagnostic steps required by OBD II must be performed under specific operating conditions. The Task Manager software organizes and prioritizes the diagnostic procedures. The job of the Task Manager is to determine if conditions are appropriate for tests to be run, monitor the parameters for a trip for each test, and record the results of the test. The following are the responsibilities of the Task Manager software

1. Test Sequence
2. Malfunction Indicator Lamp (MIL) Illumination
3. Diagnostic Trouble Codes (DTCs)
4. Trip Indicator
5. Freeze Frame Data Storage
6. Similar Conditions Window