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Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
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Experience:  Have owned a repair shop for 25 yrs.
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My 2005 Trailblazer has the Reduced Engine Power Light on.

Resolved Question:

My 2005 Trailblazer has the Reduced Engine Power Light on. What does this mean and how can I fix this?
Submitted: 6 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 6 years ago.

hi

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.

 

you may need to remove and clean the throttle body with carb cleaner,,these will get black soot and carbon in them sometimes and cause this,though the throttle actuator may be bad and need replaced

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Description and Operation

THROTTLE BODY ASSEMBLY

The throttle body for the 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 PCM. TP sensor 2 signal voltage increases as the throttle opens. TP sensor 1 signal voltage decreases as the throttle opens.

 

Service and Repair

THROTTLE BODY ASSEMBLY REPLACEMENT

REMOVAL PROCEDURE


 

  1. Remove the resonator assembly.
  2. Remove the evaporative emission (EVAP) canister purge line from the throttle body.
  3. Disconnect the throttle body electrical connector.
  4. Remove the throttle body assembly retaining bolts (1).
  5. Remove the throttle body assembly (2) and the gasket from the intake manifold.
  6. Clean the gasket surface.

INSTALLATION PROCEDURE


 

  1. Install the throttle body assembly (2) to the intake manifold with the gasket.
  2. Add sealer GM P/N 12346004 (Canadian P/N 10953480) to the throttle control module bolt threads.
  3. Install the throttle body assembly retaining bolts (1). Tighten Tighten the bolts to 10 N.m (89 lb in) .
  4. Connect the throttle body electrical connector.
  5. Install the EVAP canister purge line to the throttle body.
  6. Install the resonator assembly.


Edited by tims auto repair on 7/28/2010 at 1:38 PM EST
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