Engine reduced power

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 you lose Cruise Control ability, it means the Cruise Control, which is a pneumatic system controlled by small valves, is leaking. Check out the Cruise Control subsystem.

Could be a faulty cruise control servo activator. The power to move the cruise control Actuator is most likely coming from the Brake power hydraulic booster vacuum pipe and if the cruise control vacuum servo is failing and leaking in air you lose the brakes power hydraulics.
check the vacuum pipe coming off the power booster brake master cylinder vacuum pipe you may find a tee connector in the vacuum main pipe and follow it to see where it goes to. Could be a break in the cruise control vacuum hose but if it is only happening when the cruise control is activated a fault or leak in the cruise control servo device is the main suspect. Which you should find at the other end of the cruise control vacuum hose.

How many miles does it have on the odometer ? The reduce engine power has to do with the ETC electronic throttle control . May have TPS - throttle position sensor problem or the APP sensor . 04 Silverado REDUCED ENGINE POWER Case Study Part 1

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:
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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.

Drive by Wire Function and diagnostics by Wells

reduced engine power has to do with the electronic throttle control or drive by wire . All electronic wires under the dash on the gas pedal , electric motor on the throttle body . DTC'S - diagnostic trouble codes stored in the computer . Take it to the dealer .

may need a body control module wich needs to also be programed to car by the dealer

It reduces power to protect from engine damage. I have had this happen twice because I accidentally hit the back of the gas peddle up when I was in cruise control. It will reset once you drive in reverse. If that does not resolve the problem you might have to take it in for service.

My code on my van P0641 does anybody know what that mean

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 .