05 Mercury Montego Throttle control/sensor

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Refer to Throttle Actuator Control (TAC) System Description

Throttle Actuator Control (TAC) System Description
Purpose
The throttle actuator control (TAC) system delivers improved throttle response and greater reliability and eliminates the need for mechanical cable. The TAC system performs the following functions:
• Accelerator pedal position (APP) sensing
• Throttle positioning to meet driver and engine demands
• Throttle position sensing
• Internal diagnostics
• Cruise control functions
• Manage TAC electrical power consumption
The TAC system includes the following components:
• The APP sensors
• The throttle body assembly
• The powertrain control module (PCM)

Accelerator Pedal Position (APP) Sensor
The accelerator pedal contains 2 individual accelerator pedal position (APP) sensors within the assembly. The APP sensors 1 and 2 are potentiometer type sensors each with 3 circuits:
• A 5-volt reference circuit
• A low reference circuit
• A signal circuit
The APP sensors are used to determine the pedal angle. The powertrain control module (PCM) provides each APP sensor with a 5-volt reference circuit and a low reference circuit. The APP sensors provide the PCM with signal voltage proportional to the pedal movement. Both APP sensor signal voltages are low at rest position and increase as the pedal is applied.

Throttle Body Assembly
The throttle assembly contains the following components:
• The throttle blade
• The throttle actuator motor
• The throttle position (TP) sensor 1 and 2
• The throttle actuator control (TAC) module
The throttle body functions similar to a conventional throttle body with the following exceptions:
• There is no longer an idle air control (IAC) motor and associated air passages.
• An electric motor opens and closes the throttle valve.
• The TAC module is located within the throttle body assembly.
• The throttle blade is spring loaded in both directions and the default position is slightly open.
• There are 2 individual TP sensors within the throttle body assembly.
The TP sensors are used to determine the throttle plate angle. The TP sensors provide the powertrain control module (PCM) with a signal voltage proportional to throttle plate movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens.

Have you had it checked for codes ? Have you also had a Reduced Engine Power message ?

Engine power is usually reduced in response to a fault being registered by the computer management. A fault that would affect exhaust emissions would usually switch on the check engine light and so your engine fault is likely to be outside the scope of OBD2 and need dealer level software to diagnose.

code p 2104 refers to throttle actuator control(TAC) system--forced idle mode===causes ---wiring--TAC motor--ALL sensor--ECM
codes p 2111 refers to throttle actuator control (TAC) system--actuator stuck open====causes --throttle body--throttle valve tight tight/ sticking
also refers to TAC system --circuit malfunction=== causes wiring short to positive ---short to ground ---TP sensor ---ECM
also refers to brake vacuum---implausible signal====causes ---wiring--- vacuum sensor--- mechanical fault

Check engine light come on ? Any messages on DIC - driver information center , reduced power ,if the vehicle has it . Any other lights lite , yellow wrench symbol . Do you own a scan tool ? a professional grade scan tool , not a code reader . Do you know how to do electrical trouble shooting ? Suggest you go on you tube an check out videos on electronic throttle control .
Throttle Actuator Control (TAC) System Description
The throttle actuator control (TAC) system delivers improved throttle response and greater reliability and eliminates the need for mechanical cable. The TAC system performs the following functions:
• Accelerator pedal position sensing
• Throttle positioning to meet driver and engine demands
• Throttle position sensing
• Internal diagnostics
• Cruise control functions
• Manage TAC electrical power consumption
The TAC system components include the following:
• The accelerator pedal position (APP) sensors
• The throttle body assembly
• The throttle actuator control module
• The powertrain control module (PCM) .I strongly suggest you take it to a ASE certified repair shop

The reduced power light is pertaining to the TAC - electronic throttle control . Is the check engine light lit ? If not still may have a DTC -diagnostic trouble code stored . You probably have a bad TPS - throttle position sensor .
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 signal, 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.

Your Denali has Throttle Actuator Control (TAC) System - Electronic throttle control ! Are there any messages on the driver information center ? Reduced engine power ?
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.

You need to have it checked for DTC'S - diagnostic trouble codes , probably a accelerator pedal position (APP) sensor or TPS - throttle position sensor !

P2104 - Throttle Actuator Control (TAC) System - Forced Idle Description: The TAC system is in the failure mode effects management (FMEM) mode of forced idle. Possible Causes:

• Open or short in multiple accelerator pedal position (APP) sensor circuits.
• Damaged APP sensor.
• Damaged powertrain control module (PCM).

Diagnostic Aids: This DTC is an informational DTC and can be set in combination with a number of other DTCs which are causing the FMEM. Diagnose other DTCs first. Application Key On Engine Off Key On Engine Running Continuous Memory All

P2112 - Throttle Actuator Control (TAC) System - Stuck Closed. Description: This powertrain control module (PCM) fault status indicates the throttle plate is at a lower angle than commanded. Possible Causes:

• Binding throttle body, stuck closed.
• Damaged PCM.

Diagnostic Aids: Application Key On Engine Off Key On Engine Running Continuous Memory All GO to DV1 Are you familiar with electronic throttle control ? You have a dc electric motor on the throttle body an at the gas pedal there are APP pedal position sensors that send voltage signals to the PCM which in turn controls the electric motor opening an closing the throttle ! By what this P02112 states the throttle plate is binding , which means it could be bad or just needs to be cleaned ! You will need to disconnect the electrical connector an see if it is binding by pushing it with finger or thumb . which is ever easiest !
GO to QE1

The check engine light being on now is a different problem , Have DTC'S - diagnostic trouble codes checked ,will have something to do with electronic throttle control . That is what reduced engine power is about . It's in a reduced power mode.
Reduced Engine Power Mode
When the ECM detects a condition with the TAC system, the ECM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
• Acceleration limiting--The ECM will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.
• Limited throttle mode--The ECM will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.
• Throttle default mode--The ECM will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
• Forced idle mode--The ECM will perform the following actions:
- Limit engine speed to idle by positioning the throttle position, or by controlling the fuel and spark if the throttle is turned off.
- Ignore the accelerator pedal input.
• Engine shutdown mode--The ECM will disable fuel and de-energize the throttle actuator.

Do you know what electronic throttle control is ?
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Throttle Actuator Control (TAC) System Description

The throttle actuator control (TAC) system delivers improved throttle response and greater reliability and eliminates the need for mechanical cable. The TAC system performs the following functions:
• Accelerator pedal position sensing
• Throttle positioning to meet driver and engine demands
• Throttle position sensing
• Internal diagnostics
• Cruise control functions
• Manage TAC electrical power consumption
The TAC system includes the following components:
• The accelerator pedal position (APP) sensors
• The throttle body assembly
• The engine control module (ECM)

Your best bet , take it to a qualified repair shop .

code p2111 throttle actuator control system actuator stuck open. throttle actuator control system circuit malfunction. brake vacuum implausible signal. code p2112 throttle actuator control system actuator stuck closed.throttle actuator control system circuit malfunction. code p2135 accelerator pedal position sensor switch a b voltage correlation. throttle position sensor switch a b voltage correlation. electronic throttle position sensor switch 1 implausible signal. did not see code p210406 that code too long.