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One mechanic believes the throttle control module is bad. He notes the car is staying in a higher gear. Which is what it drives like but it is intermittent. The air conditioning fan quit blowing and the lights on the buttons in the AC panel area are not displaying. Cold air comes out but the fan does not blow it out. The faster you guy makes it come out a little faster. Question: I've disconnected the battery to reboot the module but could the Body Control Module cause the intermittent transmission problem?
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It could be the APP sensors or the throttle body throttle position sensors . What DTC'S - diagnostic trouble codes . Need to test the electrical wiring , 5 volt reference voltage. Drive by Wire Function and diagnostics by Wells
REDUCED ENGINE POWER - mass airflow sensor has nothing to do with this problem .
Throttle Actuator Control (TAC)
Reduced Engine Power Mode
When the PCM detects a condition with the TAC system, the PCM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
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Acceleration limiting--The control module will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.
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Limited throttle mode--The control module will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.
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Throttle default mode--The control module will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
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Forced idle mode--The control module will perform the following actions:
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Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned off.
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Ignore accelerator pedal input.
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Engine shutdown mode--The control module will disable fuel and de-energize the throttle actuator.
The first thing to do is replacing the transmission fluid. Metal debris
inside the transmission box gets mixed with fluid and can cause similar
problems.
The automatic transmission uses throttle position
sensor to determine position and opening of
throttle.
IF throttle position sensor is defective, the car may have problems shifting into one or more gears.
The
automatic transmission is controlled by an electronic control module,
that is energizing a set of solenoids to shift into gears.
The
control module is a rectangular box, often located behind the dash and
wired to transmission. The solenoids are attached to valve body,inside
transmission.
If a solenoid is defective, or if control module is defective, the car may have problems shifting into one or more gears.
Problems
concerning transmission control module, TPS and transmission solenoid
are usually detectable reading fault codes stored on the car main
control module (ECU/ECM).
Stored codes can be retrieved using an OBD scan reader.
If the car auto transmission is not shifting into gear, talk to the mechanic about the problem.
Only when the car has a really high mileage, or when there is a factory problem there is need to replace the gearbox.
A damaged gear box at low mileage is rather unusual.
The transmission control module is responsible for correct shifting of transmission.it is on side of tranny.
the throttle position sensor takes all the necessary measurements and sends it over to the Electronic Control Module on transmission to make it shift, if its ok! Try by changing the shift module on transmission. If this will not work check or change the TPS and check for a bad wire also. Hope this helps you out! God-Bless!
REDUCED POWER
Refer to:
• Powertrain Control Module Description for the 2.8L engine
• Powertrain Control Module Description for the 3.5L engine
Throttle Actuator Control (TAC) System
Throttle Actuator Control (TAC) Overview
The throttle actuator control (TAC) system uses vehicle electronics and components to calculate and control the position of the throttle blade. This eliminates the need for a mechanical cable attachment from the accelerator pedal to the throttle body. This system also performs the cruise control functions as well.
The TAC system components include, but are not limited to the following:
• The accelerator pedal position (APP) sensors
• The throttle body
• The powertrain control module (PCM)
Each of these components interface together to ensure accurate calculations and control of the throttle position.
Accelerator Pedal Position (APP) Sensor
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal assembly. The APP is 2 individual APP sensors within one housing. There are 2 separate signal, low reference, and 5-volt reference circuits. APP sensor 1 voltage increases as the accelerator pedal is depressed. APP sensor 2 voltage decreases as the accelerator pedal is depressed.
Throttle Body Assembly
The throttle body for the throttle actuator control (TAC) system is similar to a conventional throttle body with several exceptions. One exception being the use of a motor to control the throttle position instead of a mechanical cable. Another exception is the throttle position (TP) sensor. The TP sensor is mounted in the throttle body assembly. The TP sensor is 2 individual TP sensors within the throttle body assembly. Two separate signals, low reference, and 5-volt reference circuits are used to connect the TP sensors and the powertrain control module (PCM). TP sensor 2 signal voltage increases as the throttle opens. TP sensor 1 signal voltage decreases as the throttle opens.
Reduced Engine Power Mode
When the PCM detects a problem with the throttle actuator control (TAC) system the PCM enters one of the following Reduced Engine Power Modes:
• Acceleration Limiting--The control module will continue to use the accelerator pedal for throttle control, however the vehicle acceleration is limited.
• Limited Throttle Mode--The control module will continue to use the accelerator pedal for throttle control, however the maximum throttle opening is limited.
• Throttle Default Mode--The control module will turn OFF the throttle actuator.
• Forced Idle Mode--The control module will perform the following actions:
- Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned OFF.
- Ignore accelerator pedal input.
• Engine Shutdown Mode--The control module will disable fuel and de-energize the throttle actuator.
Have you had it checked for DTC'S - diagnostic trouble codes ?
DTC P2176
The commanded throttle position (TP) is compared to the actual TP. Both values should be within a calibrated range of each other. The powertrain control module (PCM) continuously monitors the commanded and actual TPs. If the values are greater than the calibrated range, DTC P2176 sets.
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DTC P2138
The accelerator pedal position (APP) sensors 1 and 2 are located within the accelerator pedal assembly. Each sensor has the following circuits:
• A 5-volt reference circuit
• A low reference circuit
• A signal circuit
This provides the powertrain control module (PCM) with a signal voltage proportional to accelerator pedal movement. The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 5-volt reference and decreases as the pedal is actuated.
DTC P2135
The throttle actuator control (TAC) assembly has 2 throttle position (TP) sensors mounted within the assembly. The powertrain control module (PCM) provides individual signal, ground, and 5-volt reference circuits to each sensor. Both sensors operate within a voltage range between 0.35-4.65 volts. When the throttle is opened from 0-100 percent, one sensor signal voltage increases while the other decreases. The signal circuit for TP sensor 1 is referenced to ground, and the signal circuit for TP sensor 2 is pulled up to 5 volts within the PCM.
DTC P2128
DTC P2127
DTC P2125
DTC P2123
1) Check transmission fluid level. 2) Make sure that transmission is not in limp mode. That will restrict use of transmission to low gears. Go to the nearest car dealer and do a code scanning.If there are codes stored troubleshoot the codes. 3) Check if brake lights are working. Check brakes switch. The transmission shift lock may be on. 4) Check the TPS. The throttle position sensor is located on the throttle body The
sensor detects the opening of the throttle, its output is used by
the transmission control module to determine when to shift gears. The
TPS is basically a variable resistor mounted on the throttle body. The
TPS is tested by reading volts while operating the pedal. Making sure
that voltage is in range and that there are no gaps or spikes in voltage
changing while the pedal gets pressed slowly and smoothly. 5) Test the transmission switch solenoids. The higher gears solenoids may be defective. The solenoids are part of a pack located on the valve body in the transmission. The solenoids are tested reading Ohms at their terminal. 6) If you do not find anything else check wiring to transmission control module located under the dash. Make sure you did a code scanning. 7) Look for mechanical problems (clutch, valve, gears) inside the transmission.
This doesn't sound all that unusual.. shift points vary with governor pressure. Those settings are held in the control modules. Going up a steep hill pulling a load your rpm will increase while staying in the proper lower gear to maintain optimum power. Otherwise.. bog bog break break.. Same thing happens when you stand on the throttle..the shift points become further apart.
Give your Dodge truck dealer a call.. see if they can flash the TCM and PCM with the latest program.
It could be as simple as this.. from all I have read the Transmission shift points on these trucks tend to be "early" for most drivers. Most are these days to improve mpg.
Band adjustments should have been done at 30K I believe. A fairly simply procedure.
Replacing the filter and fluid is never a bad idea and have it done at a respectable shop that can inspect the linkages.. bands and ajdustments if needed.
Mechanical linkage inspection and adjustment
Regular Maintenance schedule performed
Have operation checked by mechanic (Drive)
Error codes and Electronic modules checked for proper operation.
The last one may reveal certain components like internal pressure sensor is failing etc etc.
These are pretty standard steps to follow when trouble shooting.
It's a complex system.. and honestly I can't tell if you are really having a problem or not. Driving styles and operating environments can be vastly different. Having a good mechanic who has experience with proper operation of this vehicle drive the rig while you ride along is always a good idea.
It will shift out of overdrive upon increasing throttle , pulling hills and so on. Your overdrive probably kicks in around 35 to 45mph and kicks back out as you increase throttle. Electrically controled speed sensor to control the response. Overwise the engine would bog down to a stall. Over drive is just that. It changes the gearing ratio to over drive meaning less then final gear 4 to 1 down to 4 to 3 etc more direct drive ratio to lessen consumtion of fuel with less stress on engine. Have shift speed sensor adjusted. Don't drive in overdrive in city if most driving is under 45mph
Bad connection where the wires from the tranny plug up or you have a bad transmission control module, located I think underneath the dash next to the ECU module, looks like it except smaller.
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