2000 Sierra 1500 4.3 Bad shifting and Engine very rough idle

Discussion in 'General Chevy & GM Tech Questions' started by T ROD, Apr 19, 2017 at 11:54 AM.

  1. T ROD

    T ROD New Member

    I am working on this Sierra 1500 4.3 2WD. It does have 350k and having issues all over the spectrum.
    So this truck started out of the blue not wanting to shift into 3rd. At the time it was running good (by that I mean good idle and good take off etc. ) so I changed the trans fluid with dex3 and filter and had no change to the trans, the next day the truck would not even start checked all the plugs and wires and found no spark at the plugs. So my first thing was to change cap and rotor which got the thing started but it is very hard to start and runs really sluggish ( no power at all), It now has check engine light ABS light and Brake Light on and when it starts to reach the RPM to get to third check eng flashes. I took it to get scanned and came back with a list of codes : p0102,p0171,p0174,p0300,p0338,p0440, c0241,c0242,c0245,c0246,c0251,c0252,c0265. This truck was running great for a truck with 350k 4 days ago and now is in complete failure. I read about a ECBM ground under the body to the frame that I will try tonight, but would like to get some input of where to start.

    Note: in the last year I have done the spark plugs twice , fuel pressure regulator, fuel filter twice, spark plug wires, PCV, air filter
  2. thegawd

    thegawd Rockstar 2 Years 1000 Posts

    Yes check the grounds, with all those codes (not sure what they are without looking them up) appearing at once theres probably only one thing in common..... the grounds. One from the neg on battery to the fender, one from the passanger side firewall below the heater hoses to the frame and another from the same spot on the frame up to the passanger side, top rear of engine block. At least thats where they are on my truck.

    Im not sure how the ecm grounds and it could very well be the problem, just check the other 3 grounds first because if one of those is broken fixing the ecm ground wont fix the problem.

  3. T ROD

    T ROD New Member

    ok so I just checked the grounds cleaned everything up still running rough haven't hit the road yet gonna check more things out.
    So since I'm getting all these abs codes will that affect the trans shifting? just want to throw that out there since it ran fine last Thursday.

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