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  1. #1

    Default New Guy clueless on 07 silverado 4.8L

    Hi new guy here from Louisiana, I've got a 4.8L engine in my 07 Silverado LS. Last month the engine light came on and started flashing " Engine Power Reduced" When this happened it would barely go at all and the transmission started shifting hard. Well I got home and disconnected the battery to get rid of the fault to see if it would do it again. Well yesterday it did the same thing, brought it to Autozone to get the code read and its coming up with a throttle position voltage problem I'm guessing it the TPS. What is the problem thats going on here? Would this be covered under my 100,000 power train warranty. Can someone point me in the right direction. All these electronics are getting me frustrated.

  2. #2


    I would take your truck to the dealer and see if the issue is covered under the warranty. As for the problem itself, I'm really not sure. Someone on the forum probably has an answer for you. Welcome to the GMTC btw.
    04 ECSB Custom silver & grey, Soft 8's, BFG KO's, ReadyLift Leveling Kit, Hellwig front sway bar, K&N filter, DeeZee EZ-Down, Rhino liner, Alpine CDE103BT, Rockford 6.5's, 12" V.A.T. Hammer Pro in a Subthump box, Alpine PowerPack amp, Hifonics amp, BackRack w/ 55w 5000k HID KC Daylighters, KC light bar with 4 KC Slimlites, UWS toolbox, Shaved Antenna mod, Black Bowtie, LED backup, license plate, dome lights & 3rd brake light

  3. #3


    To the Site.......As mentioned by TELOVREHC.......if your still under warranty....the dealer would be the best route to go in correcting the problem,

    And from what you have mentioned,
    The problem with......Voltage at the Throttle Position Sensor........the Trouble Codes that talk about this Problem are Code...P0123 and P0122...which are related to the TPS....and Voltage....below is some information that goes into detail re-guarding this,

    A P0123 or P0122 code means that the the Trucks computer has detected that the TPS (throttle position sensor)...P0123 is reporting too High a Voltage.....or a P0122 is reporting too Low a Voltage,

    Symptoms may include:
    • Rough idle
    • High idle
    • Surging
    • other symptoms may also be present


    A code P0123 or P0122 may mean that one or more of the following has happened:

    • TPS not mounted securely
    • TPS circuit short to ground or another wire
    • Faulty TPS
    • Damaged computer (PCM)

    Possible Solutions

    If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
    If there are symptoms such as the engine is stumbling or hesitating, carefully inspect all wiring and connectors that lead to the TPS. More than likely the problem is with the TPS wiring. Check the voltage at the TPS (refer to a service manual for your vehicle for this specific information). If the voltage spikes or is too high (over 4.65 volts with key on, engine off), then that is indicative of a problem. Carefully trace each wire from the TPS wiring harness to check for breaks, rubbing against other components, etc.


    5.3 l 3.73 l G80

  4. #4
    Legend Bigbomber's Avatar
    Join Date
    Feb 2010


    Quote Originally Posted by TELORVEHC View Post
    I would take your truck to the dealer and see if the issue is covered under the warranty. As for the problem itself, I'm really not sure. Someone on the forum probably has an answer for you. Welcome to the GMTC btw.
    X2 on going to the dealer on this one!
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  5. #5

    mfleetwood's Avatar
    Join Date
    Jul 2010
    Denver, CO
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    Welcome!!! and I agree with others.

    Mike (Denver, CO) - 2008 Sierra 1500 Z71 SLE 5.3L 4WD

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