sensor DODGE RAM SRT-10 2006 Service Repair Manual

ASSEMBLY
HVAC HOUSING
1. Carefully install the A/C evaporator (2) into the
upper half of the HVAC housing (4).
2. Install the foam seal (3) onto the tubes of the A/C
evaporator.
3. Install the probe of the evaporator temperature
sensor (2) between the fins of the A/C evaporator.
4. Install the insulator (1) onto the bottom of the A/C
evaporator.
5. Install the defroster-air doors (1) into the lower half
of the HVAC housing (2).
6. Align the actuator coupler (3) with the defroster-air
door pivot shaft and install the coupler into side of
the HVAC housing. Be sure to install the coupler
with the coupler arm located between the two stop
tabs on the HVAC housing.

7. Install the blend-air doors (1) into each of the two
blend door plates (2).
8. Align the actuator coupler (3) with each blend-air
door pivot shaft and install the coupler into side of
each blend door plate. Be sure to install each cou-
pler with the coupler arm located between the two
stop tabs on each blend door plate.
9. Position the lower blend door assembly (2) into the
lower half of the HVAC housing (3) and fully
engage the three retaining tabs (1).
10. Position the upper blend door assembly into the
upper half of the HVAC housing and fully engage
the three retaining tabs.
NOTE: Route the wire lead for the evaporator tem-
perature sensor into the opening located on the
upper half of the HVAC housing prior to installing
the lower half of the HVAC housing.
11. Position the two halves of the HVAC housing
together (3).
12. Install the fifteen screws (6) that secure the two
housing halves together. Tighten the screws to 2.2
Nꞏm (20 in. lbs.).
13. Install the foam seal (4) onto the evaporator con-
densate drain tube (5).
14. Connect the linkage rod (1) to the two blend-air
door levers (2) located on the back of the HVAC
housing.

28. Install the air inlet housing (3) onto the top of the
HVAC housing (4) (Refer to 24 - HEATING & AIR
CONDITIONING/DISTRIBUTION/HOUSING-
HVAC - AIR INLET HOUSING - INSTALLATION).
29. Install the HVAC wire harness (1) onto the HVAC
housing. Make sure the wires are routed through
all wiring retainers.
30. Connect the HVAC wire harness to evaporator
temperature sensor (2).
31. Position the blower motor resistor (7) and the
blower motor (2) into the bottom of the HVAC
housing (5).
32. Install the screws (4 and 6) that secure the blower
motor resistor and the blower motor to the HVAC
housing. Tighten the screws to 2.2 Nꞏm (20 in.
lbs.).
33. Connect the HVAC wire harness connectors (1
and 3) to blower motor resistor and the blower
motor.
34. Position the recirculation door actuator (3) onto
the air inlet housing (4) and install the retaining
screws. Tighten the screws to 2.2 Nꞏm (20 in.
lbs.).
35. Position the mode door actuators (1) and the
blend door actuators (2) onto the HVAC housing
(5) and install the retaining screws. Tighten the
screws to 2.2 Nꞏm (20 in. lbs.).
36. Connect the HVAC wire harness connectors to the
actuators.
37. Install the HVAC housing assembly (Refer to 24 -
HEATING & AIR CONDITIONING/DISTRIBUTION/
HOUSING-HVAC - HVAC HOUSING ASSEMBLY -
INSTALLATION).

AIR INLET HOUSING
NOTE: The air inlet housing must be removed from HVAC housing and disassembled for service of the
recirculation-air door.
NOTE: If the seals on the air door is deformed or
damaged, the air door must be replaced.
1. Position the recirculation-air door (1) into the air
inlet housing (2).
CAUTION: Make sure that the recirculation-air
door pivot shaft is properly seated in the pivot
seat located in the air inlet housing.
2. Align the actuator coupler (3) with the recirculation-
air door pivot shaft and install the coupler until the
coupler retaining tabs are fully engaged to the air
inlet housing. Be sure to install the coupler with the
coupler arm located between the two stop tabs on
the air inlet housing.
3. Install the two foam insulators (2) into the air inlet
housing (1).
4. Install the air inlet housing onto the HVAC housing
(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HOUSING-HVAC - AIR INLET
HOUSING - INSTALLATION).
INSTALLATION
HVAC HOUSING ASSEMBLY
NOTE: The HVAC housing must be removedfrom the vehicle and disassembled for service of the A/C evap-
orator, evaporator temperature sensor, mode-air and blend-air doors.

EVAPORATOR-A/C
DESCRIPTION
The A/C evaporator (1) for the heating-A/C system is
located within the HVAC housing, behind the instru-
ment panel. The A/C evaporator and its insulator (2)
are positioned in the HVAC housing so that all air
entering the housing must pass over the evaporator
fins before it is distributed through the heating-A/C
system ducts and outlets. However, air passing over
the evaporator fins will only be conditioned when the
A/C compressor is engaged and circulating refrigerant
through the A/C evaporator.
The A/C evaporator can be serviced by removing and
disassembling the HVAC housing assembly.
OPERATION
Refrigerant enters the A/C evaporator through the A/C orifice tube as a low-temperature, low-pressure mixture of
liquid and gas. As air flows over the fins of the A/C evaporator, the humidity in the air condenses on the fins, and
the heat from the air is absorbed by the refrigerant. Heat absorption causes the refrigerant to boil and vaporize. The
refrigerant becomes a low-pressure gas when it leaves the A/C evaporator.
The A/C evaporator cannot be repaired and, if faulty or damaged, it must be replaced.
REMOVAL
1. RemovetheHVAChousingandplaceitonawork-
bench (Refer to 24 - HEATING & AIR CONDITION-
ING/DISTRIBUTION/HOUSING-HVAC -
REMOVAL).
2. Disassemble the HVAC housing to access the A/C
evaporator (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION/HOUSING-HVAC - DIS-
ASSEMBLY).
3. Remove the probe of the evaporator temperature
sensor (1) from the fins of the A/C evaporator (2)
and position the wire lead (3) out of the way.
NOTE: If the foam insulator around the A/C evap-
orator is deformed or damaged, the insulator must
be replaced.
4. Carefully lift the A/C evaporator and the foam insu-
lator out of the upper half of the HVAC housing (4).
NOTE: If the foam seal around the evaporator tap-
ping block is deformed or damaged, the seal must be replaced.
5. If required, remove the foam seal from the inlet and outlet tubes of the A/Cevaporator.

INSTALLATION
NOTE: If the A/C evaporator is being replaced, add 60 milliliters (2 fluid ounces) of refrigerant oil to the
refrigerant system. Use only refrigerant oil of the type recommended for the A/C compressor in the vehicle.
NOTE: Make sure that the foam insulator is prop-
erly positioned in the HVAC housing.
1. Carefully install the A/C evaporator (2) and its foam
insulator into the upper half of the HVAC housing
(4).
2. Install the probe of the evaporator temperature
sensor (1) between the fins of the A/C evaporator.
3. Route the wire lead (3) of the evaporator tempera-
ture sensor into the opening located on the upper
half of the HVAC housing.
4. Assemble the HVAC housing (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION/
HOUSING-HVAC - ASSEMBLY).
5. Install the HVAC housing (Refer to 24 - HEATING
& AIR CONDITIONING/DISTRIBUTION/HOUSING-
HVAC - INSTALLATION).

EMISSIONS CONTROL
DESCRIPTION
STATE DISPLAY TEST MODE
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 switchposition versus an open circuit, a short
circuit, or a defective switch. If the State Display screen shows the changefromHIGHtoLOWorLOWtoHIGH,
assume the entire switch circuit to the PCM functions properly. Connect the DRB scan tool to the data link con-
nector and access the state display screen. Then access either State Display Inputs and Outputs or State Display
Sensors.
CIRCUIT ACTUATION TEST MODE
The Circuit Actuation Test Mode checks for proper operation of output circuits or devices the Powertrain Control
Module (PCM) may not internally recognize. The PCM attempts to activate these outputs and allow an observer to
verify proper operation. Most of the tests provide an audible or visual indication of device operation (click of relay
contacts, fuel spray, etc.). Except for intermittent conditions, if a device functions properly during testing, assume the
device, its associated wiring, and driver circuit work correctly. Connect the DRB scan tool to the data link connector
and access the Actuators screen.
DIAGNOSTIC TROUBLE CODES
A Diagnostic Trouble Code (DTC) indicates the PCM has recognized an abnormal condition in the system.
Remember that DTC’s are the results of a system or circuit failure, but do not directly identify the failed
component or components.
BULB CHECK
Each time the ignition key is turned to the ON position, the malfunction indicator (check engine) lamp on the instru-
ment panel should illuminate for approximately 2 seconds then go out. Thisis done for a bulb check.
OBTAINING DTC’S USING DRB SCAN TOOL
1. Obtain the applicable Powertrain Diagnostic Manual.
2. Obtain the DRB Scan Tool.
3. Connect the DRB Scan Tool to the data link (diagnostic) connector. This connector is located in the passenger
compartment at the lower edge of instrument panel, and near the steering column.
4. Turn the ignition switch on and access the “Read Fault” screen.
5. Record all the DTC’s and “freeze frame” information shown on the DRB scantool.
6. To erase DTC’s, use the “Erase Trouble Code” data screen on the DRB scan tool.Do not erase any DTC’s
until problems have been investigated and repairs have been performed.
TA S K M A N A G E R
The 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’.
MONITORED SYSTEMS
There are new electronic circuit monitors that check fuel, emission, engine and ignition performance. These moni-
tors use information from various sensor circuits to indicate the overalloperation of the fuel, engine, ignition and
emission systems and thus the emissions performance of the vehicle.
The fuel, engine, ignition and emission systems monitors do not indicate aspecific component problem. They do
indicate that there is an implied problem within one of the systems and thata specific problem must be diagnosed.
If any of these monitors detect a problem affecting vehicle emissions, theMalfunction Indicator Lamp (MIL) will be
illuminated. These monitors generate Diagnostic Trouble Codes that can be displayed with the MIL or a scan tool.

The following is a list of the system monitors:
Misfire Monitor
Fuel System Monitor
Oxygen Sensor Monitor
Oxygen Sensor Heater Monitor
Catalyst Monitor
Leak Detection Pump Monitor (if equipped)
All these system monitors require two consecutive trips with the malfunction present to set a fault.
Refer to the appropriate Powertrain Diagnostics Procedures manual for diagnostic procedures.
The following is an operation and description of each system monitor:
OXYGEN SENSOR (O2S) MONITOR
Effective control of exhaust emissions is achieved by an oxygen feedback system. The most important element of
the feedback system is the O2S. The O2S is located in the exhaust path. Once it reaches operating temperature
300° to 350°C (572° to 662°F), the sensor generates a voltage that is inversely proportional to the amount of oxy-
gen in the exhaust. The information obtained by the sensor is used to calculate the fuel injector pulse width. This
maintains a 14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio, the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrogen oxide (NOx) from the exhaust.
The O2S is also the main sensing element for the Catalyst and Fuel Monitors.
The O2S can fail in any or all of the following manners:
slow response rate
reduced output voltage
dynamic shift
shortedoropencircuits
Response rate is the time required for the sensor to switch from lean to richonce it is exposed to a richer than
optimum A/F mixture or vice versa. As the sensor starts malfunctioning, itcould take longer to detect the changes
in the oxygen content of the exhaust gas.
The output voltage of the O2S ranges from 0 to 1 volt. A good sensor can easilygenerate any output voltage in this
range as it is exposed to different concentrations of oxygen. To detect a shift in the A/F mixture (lean or rich), the
output voltage has to change beyond a threshold value. A malfunctioning sensor could have difficulty changing
beyond the threshold value.
OXYGEN SENSOR HEATER MONITOR
If there is an oxygen sensor (O2S) shorted to voltage DTC, as well as a O2S heater DTC, the O2S fault MUST be
repaired first. Before checking the O2S fault, verify that the heater circuit is operating correctly.
Effective control of exhaust emissions is achieved by an oxygen feedback system. The most important element of
the feedback system is the O2S. The O2S is located in the exhaust path. Once it reaches operating temperature
300°C to 350°C (572°F to 662°F), the sensor generates a voltage that is inversely proportional to the amount of
oxygen in the exhaust. The information obtained by the sensor is used to calculate the fuel injector pulse width. This
maintains a 14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio, the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrogen oxide (NOx) from the exhaust.
The voltage readings taken from the O2S sensor are very temperature sensitive. The readings are not accurate
below 572°F (300°C). Heating of the O2S sensor is done to allow the engine controllertoshifttoclosedloopcontrol
as soon as possible. The heating element used to heat the O2S sensor must be testedtoensurethatitisheating
the sensor properly.
The O2S sensor circuit is monitored for a drop in voltage. The sensor outputis used to test the heater by isolating
the effect of the heater element on the O2S sensor output voltage from the other effects.
LEAK DETECTION PUMP MONITOR (IF EQUIPPED)
The leak detection assembly incorporates two primary functions: it must detect a leak in the evaporative system and
seal the evaporative system so the leak detection test can be run.

The primary components within the assembly are: A three port solenoid thatactivates both of the functions listed
above; a pump which contains a switch, two check valves and a spring/diaphragm, a canister vent valve (CVV) seal
which contains a spring loaded vent seal valve.
Immediately after a cold start, between predetermined temperature thresholds limits, the three port solenoid is briefly
energized. This initializes the pump by drawing air into the pump cavity and also closes the vent seal. During non
test conditions the vent seal is held open by the pump diaphragm assembly which pushes it open at the full travel
position. The vent seal will remain closed while the pump is cycling due to the reed switch triggering of the three
port solenoid that prevents the diaphragm assembly from reaching full travel. After the brief initialization period, the
solenoid is de-energized allowing atmospheric pressure to enter the pumpcavity, thus permitting the spring to drive
the diaphragm which forces air out of the pump cavity and into the vent system. When the solenoid is energized
and de energized, the cycle is repeated creating flow in typical diaphragmpump fashion. The pump is controlled in
2 modes:
Pump Mode: The pump is cycled at a fixed rate to achieve a rapid pressure build in order to shorten the overall test
length.
Test Mode: The solenoid is energized with a fixed duration pulse. Subsequent fixed pulses occur when the dia-
phragm reaches the Switch closure point.
The spring in the pump is set so that the system will achieve an equalized pressure of about 7.5” H20. The cycle
rate of pump strokes is quite rapid as the system begins to pump up to this pressure. As the pressure increases, the
cycle rate starts to drop off. If there is no leak in the system, the pump would eventually stop pumping at the equal-
ized pressure. If there is a leak, it will continue to pump at a rate representative of the flow characteristic of the size
of the leak. From this information we can determine if the leak is larger than the required detection limit (currently
set at .040” orifice by CARB). If a leak is revealed during the leak test portion of the test, the test is terminated at
the end of the test mode and no further system checks will be performed.
After passing the leak detection phase of the test, system pressure is maintained by turning on the LDP’s solenoid
until the purge system is activated. Purge activation in effect creates a leak. The cycle rate is again interrogated and
when it increases due to the flow through the purge system, the leak check portion of the diagnostic is complete.
The canister vent valve will unseal the system after completion of the testsequence as the pump diaphragm assem-
bly moves to the full travel position.
Evaporative system functionality will be verified by using the stricter evap purge flow monitor. At an appropriate
warm idle the LDP will be energized to seal the canister vent. The purge flowwill be clocked up from some small
value in an attempt to see a shift in the02 control system. If fuel vapor, indicated by a shift in the 02 control, is
present the test is passed. If not, it is assumed that the purge system is notfunctioning in some respect. The LDP
is again turned off and the test is ended.
MISFIRE MONITOR
Excessive engine misfire results in increased catalyst temperature and causes an increase in HC emissions. Severe
misfires could cause catalyst damage. To prevent catalytic convertor damage, the PCM monitors engine misfire.
The Powertrain Control Module (PCM) monitors for misfire during most engine operating conditions (positive torque)
by looking at changes in the crankshaft speed. If a misfire occurs the speedof the crankshaft will vary more than
normal.
FUEL SYSTEM MONITOR
To comply with clean air regulations, vehicles are equipped with catalytic converters. These converters reduce the
emission of hydrocarbons, oxides of nitrogen and carbon monoxide. The catalyst works best when the Air Fuel (A/F)
ratio is at or near the optimum of 14.7 to 1.
The PCM is programmed to maintain the optimum air/fuel ratio of 14.7 to 1. This is done by making short term
corrections in the fuel injector pulse width based on the O2S sensor output. The programmed memory acts as a self
calibration tool that the engine controller uses to compensate for variations in engine specifications, sensor toler-
ances and engine fatigue over the life span of the engine. By monitoring theactual fuel-air ratio with the O2S sen-
sor (short term) and multiplying that with the program long-term (adaptive) memory and comparing that to the limit,
it can be determined whether it will pass an emissions test. If a malfunction occurs such that the PCM cannot main-
tain the optimum A/F ratio, then the MIL will be illuminated.

CATALYST MONITOR
To comply with clean air regulations, vehicles are equipped with catalytic converters. These converters reduce the
emission of hydrocarbons, oxides of nitrogen and carbon monoxide.
Normal vehicle miles or engine misfire can cause a catalyst to decay. This can increase vehicle emissions and
deteriorate engine performance, driveability and fuel economy.
The catalyst monitor uses dual oxygen sensors (O2S’s) to monitor the efficiency of the converter. The dual O2S’s
sensor strategy is based on the fact that as a catalyst deteriorates, its oxygen storage capacity and its efficiency are
both reduced. By monitoring the oxygen storage capacity of a catalyst, itsefficiency can be indirectly calculated. The
upstream O2S is used to detect the amount of oxygen in the exhaust gas beforethe gas enters the catalytic con-
verter. The PCM calculates the A/F mixture from the output of the O2S. A low voltage indicates high oxygen content
(lean mixture). A high voltage indicates a low content of oxygen (rich mixture).
When the upstream O2S detects a lean condition, there is an abundance of oxygen in the exhaust gas. A function-
ing converter would store this oxygen so it can use it for the oxidation of HCand CO. As the converter absorbs the
oxygen, there will be a lack of oxygen downstream of the converter. The output of the downstream O2S will indicate
limited activity in this condition.
As the converter loses the ability to store oxygen, the condition can be detected from the behavior of the down-
stream O2S. When the efficiency drops, no chemical reaction takes place. This means the concentration of oxygen
will be the same downstream as upstream. The output voltage of the downstream O2S copies the voltage of the
upstream sensor. The only difference is a time lag (seen by the PCM) betweenthe switching of the O2S’s.
To monitor the system, the number of lean-to-rich switches of upstream anddownstream O2S’s is counted. The
ratio of downstream switches to upstream switches is used to determine whether the catalyst is operating properly.
An effective catalyst will have fewer downstream switches than it has upstream switches i.e., a ratio closer to zero.
For a totally ineffective catalyst, this ratio will be one-to-one, indicating that no oxidation occurs in the device.
The system must be monitored so that when catalyst efficiency deteriorates and exhaust emissions increase to over
the legal limit, the MIL will be illuminated.
TRIP DEFINITION
The term “Trip” has different meanings depending on what the circumstances are. If the MIL (Malfunction Indicator
Lamp) is OFF, a Trip is defined as when the Oxygen Sensor Monitor and the Catalyst Monitor have been completed
in the same drive cycle.
When any Emission DTC is set, the MIL on the dash is turned ON. When the MIL is ON, it takes 3 good trips to turn
the MIL OFF. In this case, it depends on what type of DTC is set to know what a “Trip” is.
For the Fuel Monitor or Mis-Fire Monitor (continuous monitor), the vehicle must be operated in the “Similar Condition
Window” for a specified amount of time to be considered a Good Trip.
If a Non-Continuous OBDII Monitor fails twice in a row and turns ON the MIL, re-running that monitor which previ-
ously failed, on the next start-up and passing the monitor, is considered tobeaGoodTrip.Thesewillincludethe
following:
Oxygen Sensor
Catalyst Monitor
Purge Flow Monitor
Leak Detection Pump Monitor (if equipped)
EGR Monitor (if equipped)
Oxygen Sensor Heater Monitor
If any other Emission DTC is set (not an OBDII Monitor), a Good Trip is considered to be when the Oxygen Sensor
Monitor and Catalyst Monitor have been completed; or 2 Minutes of engine run time if the Oxygen Sensor Monitor
or Catalyst Monitor have been stopped from running.
It can take up to 2 Failures in a row to turn on the MIL. After the MIL is ON, it takes3GoodTripstoturntheMIL
OFF. After the MIL is OFF, the PCM will self-erase the DTC after 40 Warm-up cycles. A Warm-up cycle is counted
when the ECT (Engine Coolant Temperature Sensor) has crossed 160°F (71.1C) and has risen by at least 40°F
(4.4°C) since the engine has been started.