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Fly-by-Wire throttle body exposed!
Posted to Technical Discussion Forum on 2/24/2010 68 Replies

Today I replaced a throttle body on this truck and decided to look for the failure. This one failed with TP sensors 1+2 disagree. While performing a throttle sweep test KOEO, it would fail and default every time around 75% throttle. Once it failed, it would not move until a key cycle, and sometimes it would require a code clear before it would move again.

I found it interesting and thought others might also.

TAC throttle body

motor, gears and butterfly

Closeup of TP arm and potentiometer

You'll note 2 terminals to the motor, yes 12V will snap it open or closed :) Didn't see anything visibly wrong with the tracks, although there was definitely a problem there. If you look closely, you'll see where a strip runs all the way around the outermost track and connects to the opposite end of track 2. Pretty simple really.

Robert from Florida

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car Vehicle Data

2008 GMC Sierra 1500 SL 4.8L

Engine4.8 L
Trans4-speed Automatic (Electronic)