Throttle position sensor

reduced engine power sensor ??? There is no reduced engine power sensor, Now a message on the DIC -driver information center, reduced engine power is a different story . Reduced Engine Power Refer to Powertrain Control Module Description in Engine Controls


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:
• Acceleration limiting--The PCM will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.
• Limited throttle mode--The PCM will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.
• Throttle default mode--The PCM will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
• Forced idle mode--The PCM 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 PCM will disable fuel and de-energize the throttle actuator.

You need to hook up a scan tool an check for DTC'S - diagnostic trouble codes .

engine losing power sign ??? .You mean ENGINE POWER REDUCED ? This has to do with electronic throttle control -Throttle Actuator Control (TAC) System Description

The throttle actuator control (TAC) system is used to improve emissions, fuel economy, and driveability. The TAC system eliminates the mechanical link between the accelerator pedal and the throttle plate. The TAC system eliminates the need for a cruise control module and idle air control motor. The following is a list of TAC system components:
• The accelerator pedal assembly includes the following components:
- The accelerator pedal
- The accelerator pedal position (APP) sensor 1
- The APP sensor 2
• The throttle body assembly includes the following components:
- The throttle position (TP) sensor 1
- The TP sensor 2
- The throttle actuator motor
- The throttle plate
• The engine control module (ECM)

TAC System Default Actions/Reduce Power Modes
There are 2 reduce power modes that the engine control module (ECM) can default to if an error is detected in the throttle actuator control (TAC) system. If an accelerator pedal position (APP) sensor 1 or APP sensor 2 circuit fault, throttle position (TP) sensor 2 circuit fault, or if a TP sensor 1 circuit fault is detected with some APP angle, the ECM goes into one of the 2 reduce power modes. In this mode, the engine torque is limited so that the vehicle cannot reach speeds of more than 100 km/h (60 mph). The ECM remains in this reduce power mode during the entire ignition cycle even if the fault is corrected.
If there is a condition with the throttle actuator control circuits, throttle actuator command vs actual position fault, return spring check fault, or a TP sensor 1 circuit fault, the ECM goes into the other reduce engine power mode. In this mode, the engine speed is limited to 2,500 RPM and the 3-6 fuel injectors are randomly turned OFF. At this time the Reduced Power indicator is commanded ON. The ECM remains in the reduce power mode during the entire ignition cycle even if the fault is corrected. Observe, if a TP sensor 1 or throttle actuator control circuit fault is present at the time the vehicle is at idle, with no accelerator pedal angle, the engine may stall.
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You need to have a qualified repair shop check it out.

if they didn't read the fault codes before starting work, they are repairing by replacement and that is not good
if a sensor is faulty and it could be a cam shaft sensor as well as a crankshaft sensor , normally it misfires or stops altogether
the ECM is in limp mode and that reduced the engine power and if there was a sensor problem it would not just reduce power and put the light on but would show up in a define manner
engine lights also come on it there is a transmission problem and that will also initiate the limp mode
have the fault codes read to determine the faulty part/ sensor

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:
?€¢
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 motor and the throttle will return to the spring loaded default position.

?€¢
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.

Refer to
?€¢
Powertrain Control Module Description for the 4.8L, 5.3L and 6.0L engine

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.
Did you have it checked for DTC's - diagnostic trouble code's related to the reduced engine power ?
All so has APP sensor gas pedal !
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 engine control module (ECM) provides each APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensors provide the ECM with signal voltage proportional to the pedal movement. The APP sensor 1 signal voltage at rest position is less than 1 volt and increases to more than 4 volts as the pedal is actuated. The APP sensor 2 signal voltage at rest position is less than 0.6 volt and increases to more than 2 volts as the pedal is actuated.
Your best bet is take your vehicle to the dealer !
al

This may be mounted on the throttle body and if it is you may, hopefully , be able to replace it . In some vehicles it can just be unbolted and replaced , on other vehicles that whole throttle body has to be replaced because some clever design person has decided that the pedal position sensor should be integrated. This can mean having to spend a thoudand or two instead of fifty or a hundred dollars.
Anyway, if it is replaceable should take less than an hour to sort out stop the vehicle cutting out?


good luck

Hi Steve , your vehicle has electronic throttle control . I don't know if you are aware of this. The gas pedal have position sensors an a wiring connector with 4-6 wires .these wires are connected to the engine computer . an there is a electric motor on the throttle body assembly , the computer opens an closes the throttle . You probably have codes stored in the engine computer .
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:
?€¢
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 motor and the throttle will return to the spring loaded default position.

?€¢
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.

Drive by Wire Function and diagnostics by Wells

look for a vacuum leak, if you have a check engine light it will probably point to the Idle Air Control, or possible the throttle position sensor.

My 2008 SRX also had this problem, at first I would turn the engine off and that would fix the problem, but then both the check engine light and the reduce engine power light would come right back on. I brought it to my local mechanic and the code that came up was for the timing chain or the crank shaft. They checked with cadillac and they had problems with timing chain so that was replaced. It was fine for a few days and is now doing the same exact thing. Can anyone help?

The reduced engine power happens because there is a problem with the electronic throttle control . Some people call it drive by wire ! The gas pedal has sensors inside , position sensors , connected electrical to the PCM - engine computer , the throttle body on the engine has a DC electric motor an also has position sensors . These are also connected to the PCM electrical . The PCM reads the position sensors which indicate how much your pressing on the gas pedal . then hopefully it opens the throttle the same amout .

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)

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.

GM Electronic Throttle Body Circuit Descriptions And Testing Tips

Tons of videos on youtube for these systems , there can be a variety problems , from wiring , worn out sensors , the DC motor , computer etc....