Check enginel light and “reduced power” on the DIC came on

Discussion in 'Engine & Drivetrain' started by Steve Waddington, Sep 16, 2018 at 1:15 AM.

  1. Steve Waddington

    Steve Waddington Member

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    Driving the Tahoe tonight, and kinda “stepped on it”, to accelerate quickly when all of a sudden the check engine light came on and stayed on and the DIC displayed “reduced power.” I could still drive it although slowly.
    Got the car home ( only about 3 blocks away) and turned it off immediately.
    (The strange thing is, I drove the car all day today with no problems whatsoever, on the freeway on the streets, etc.)
    Parked the car for five minutes went back out and started it up… no check engine light no ‘reduced power’ on the DIC... drove it for a couple of miles and it was just fine, as if nothing happened. Weird!
    So, I guess now I need to get one of those things that reads the error codes when you plug it into the onboard diagnostic port, to find out what’s going on! What do you call it, and where do I get one?
     
  2. swathdiver

    swathdiver Full Access Member

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    A code reader or a bi-directional scan tool like the Tech2?

    Check your grounds, battery terminals, cables tomorrow. How old is the battery?

    A couple of guys on here had the very same symptoms happen to them too. Maybe a year ago to as recent as the spring.
     
  3. Steve Waddington

    Steve Waddington Member

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    I bought this 03 Tahoe last month. Learning about these vehicles as I go. The first lesson was when the fuel pump crapped out and had to have it and the filter replaced. (Cost a small fortune!) The second is finding out about Nivomat shocks! (Gonna cost another small fortune!). Had to get 5 new tires too. And of course the tax, title, registration and insurance.
    Now this!

    I have no idea how old the battery is, but it seems plenty robust...engine starts right up. All my gauges seem to work and it all looks good.

    I guess I can check the grounds... as soon as I find out where they are. Clean the battery cables, etc.

    Don’t know what a Tech2 is, don’t even know how to use a code reader. Remember, my other car is a 68 Coupe de Ville... carbureted, with points and a cap and rotor and one coil! And a fuel pump and filter where you can see them! LOL, yeah, I’m a dinosaur!
     
  4. Doubeleive

    Doubeleive Elite Member Supporting Member

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    it is fairly common for this scenario to be caused by a throttle body error, sometimes a code is stored such as p0121, it can be completely random and may only occur once in a blue moon but if it happens several times then replacing the throttle body is usually the fix, luckily there not very expensive nor hard to replace at all. sometimes it can be a short in the harness also or possibly the sensor behind the gas pedal. but if you go by pretty much any auto parts store they will usually check if you have any codes stored for free just go to the counter and ask if they can check/scan for a code.
     
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  5. Steve Waddington

    Steve Waddington Member

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    OK, so I went to Pep Boys and bought this little PT Diagnostic Scan Tool (W2977) for 20 bucks. It's really just a code reader, but it erases and re-sets, so it's better than nothing...until I learn what I am doing.

    So I plugged it in and followed the directions. I was half-expecting to see a BUNCH of codes pop up, because I've only had this Tahoe for less than a month, and who knows what kind of issues could be lurking, right?

    YES! Just one code...P2135.

    The booklet only goes to P0999, but a quick search on the internet confirms it has something to do with the TPS...could be a faulty sensor, or connection, or ground or bad throttle body itself. Also, good to know that you don't have to replace the entire throttle body, just the sensor, if it's bad.

    I've been driving around ever since I had the issue, and it has not repeated. I guess when I turned off the motor, waited awhile, then turned it back on, it somehow rest itself? The CEL is not on, and the DIC message is gone, but do I need to erase the code with this little PT reader Tool?

    It's not by any means a complete scanner, but I'm glad I bought this little reader to keep in the glove box.
     
  6. Scottydoggs

    Scottydoggs Full Access Member

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    if the light went out on its own, like you didnt clear it with the scanner. id think you might have a wire to the plug issue. the wires tend to break off the pinned part inside the plug. if you tug on each wire going to the plugs on the tb, one just might pull right off. then you found the problem for sure.
     
  7. Steve Waddington

    Steve Waddington Member

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    Does it matter whether or not I clear it with the scanner?
     
  8. Scottydoggs

    Scottydoggs Full Access Member

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    not really, but is the light went off on its own, id suspect a bad wire first before spending money on new sensors or gas pedals. new pig tail is like 15 bucks or less.
     
  9. Tonyrodz

    Tonyrodz Full Access Member

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    I've been getting this for a while. I changed the throttle body and the pigtail, and I still get the reduced engine power. I also get P2135. I just keep resetting the check engine light with my scanner and it's fine. But it's been happening a lot lately.
     
  10. Steve Waddington

    Steve Waddington Member

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    What a PITA! Wonder what it could be? So, essentially, you replaced the throttle body and pigtail for nothing ? So it’s gotta be a ground or a faulty wire somewhere?
    Mine reset on it own, but I’m glad I have the scanner now to reset it right away if it happens again.
     
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