1. Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Shifting problem

Discussion in 'GM Allison' started by Michael Welch, May 14, 2018.

  1. Michael Welch

    Michael Welch New Member

    1
    0
    May 14, 2018
    Eugene, Oregon
    I have a 2004 Chevrolet Silverado 2500 HD. The problem start with the shift from 2nd to 3rd. When you get on it hard it will not shift untill you let of the throttle. Shifts fine while driving normal. Now when you are doing like 55 and you step on it it will down shift and only do about 2300rpm and go and faster untill you let off the throttle and let it shift up. Any idea what is wrong?
     
  2. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    8,978
    2,302
    May 9, 2008
    ZEPHYRHILLS FL
    When did you last change your fuel filter? Shifting problems is one of the 1st signs of a plugging fuel filter.
     
    MrMarty51 likes this.
  3. Matthew Thieme

    Matthew Thieme New Member

    10
    19
    May 14, 2018
    Detroit
    If slow flow from a filter can cause it, could a sluggish lift pump have the same effect?
     
    MrMarty51 likes this.
  4. btfarm

    btfarm 330,000 Worth and counting Staff Member Moderator

    16,578
    2,330
    May 12, 2008
    Sandwich, Illinois
    Along with the possible fuel filter issue, when was the last time the Allison spin on filter was changed?
     
    MrMarty51 likes this.
  5. MrMarty51

    MrMarty51 Well-Known Member

    1,231
    1,094
    Aug 1, 2017
    Miles City, Montana
    If the TOW MODE is engaged, would that affect its shifting ?
     
  6. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    8,978
    2,302
    May 9, 2008
    ZEPHYRHILLS FL
    Tow haul mode raises the part throttle shift points and locks the converter in 2nd gear. Otherwise they aren't that different. A plugged fuel filter, boost problems(boost leak), and dirty MAF are the normal culprits. A plugged spin on can cause slippage since you'll lose pressure to the valve body.
     

Share This Page