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  1. #1

    Default Transmission wont shift

    In my 94 z71 my transmission wont shift ive changed the fluids and the filter and it still wont shift but the only way it will shift is if i let off the throttle and then push back on it? Does any one know what i need to do to fix this problem?

  2. #2


    Lets see what we're dealing with first.

    Miles, engine & tranny type, history of issues, how long a problem, etc?

    10 Chevy Traverse LT AWD
    02 Chevy Trailblazer LS (110K+ miles - loaded except for 4WD - WRECKED!)
    99 Chevy Cavalier LS (105K+ miles - commuter car)
    78 Chevy Suburban Silverado (454, 3/4 ton)
    62 GMC 3/4 ton Pickup (350 police interceptor)

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  3. #3


    its got 118,000 on it its got a 4L60E and i bought it this summer but i talked to the guy and he said it shifted perfect when i bought it and it shifted fine when i got the motor in it but about 2 weeks after i got it running it started doin it.

  4. #4


    Welcome to the club. Try some Lucas oil trans fix. It helps free up sticking valves in the trans. Its cheap and worth a try. Also when you changed the fluid and filter was there anything in the pan and what did the fluid look like?

    2005 Chevy Silverado Z71 Crew Cab
    6" Skyjacker lift w/Edlebrock dual front remote resoviour shocks, single rear remote. Rancho skid-plate.
    17" x 9" M/T Classic Lock Wheels, 35" BFG A/T or M/T tires
    4.10 PercisionGears w/factory locker, T/A Performance rear-end cover
    Banks CAI intake, ported throttlebody, JBA coated headers, over-sized Magnaflow cats, Magnaflow cat back exhaust, Diablo tuned
    B&M aluminum deep transmission pan
    Warn brush guard w/Warn 9.5 XP winch, PIAA bulbs, Line-X bedliner, AWS Black tool chest, Extang tonneau cover
    Weather Tech floor mats
    Cover-Craft seat covers
    Dash mat cover
    Formula One window tint
    One black Lab in rear seat.

  5. #5


    I don't know diddly about transmissions, but I think the engine control computer factors engine speed and vehicle speed VSS together to control shifting. If you get it to shift letting off the gas, maybe there is a vacuum input on your computer that is receiving or sending a bad signal too.

  6. #6


    i havent tried lucus but i did change the fluid and filter nd it didnt have anything in the pan

  7. #7
    Sr. Engineer
    Join Date
    Dec 2011
    11-22-boogie woogie avenue


    You put a motor in the truck? Has the service light come on or abs light. Usually if it is vss /vehicle speed sensor will get a abs light....or any of these
    Vss abs.. tps/throttle position sensor drac... brake switch..speedo.. pcm.. are tied to the transmission.
    Check the harness to trans. good for breakage bare spot. Can you manually shift through gears? Is speedo bouncing/ erratic?
    Last edited by dipstick; 12-14-2011 at 09:05 PM.

  8. #8


    yeah and the check engine lights on and cant manually shift it and the mass airflow sensor is all messed up

  9. #9
    Sr. Engineer
    Join Date
    Dec 2011
    11-22-boogie woogie avenue


    Yeah to what ..on the speedo? What engine do you have in the 94? 94 had 4.3 vortec with maf/ mass air flow. If it is a 5.7 /350 no maf.or 5.0/305
    Is abs/antilock light on? Need to scan for codes. should be a link here how to check codes.. if not look up my posts will find one with info.
    codes are great will narrow problems down. I could tell you how to check vss.. and all might still have to .
    So scan keep things simpler. If you do have a maf need to replace or clean.. make sure all down stream of maf is sealed tight.
    Need to fix this first will cause all sorts of symptoms.

    ---------- Post added at 03:06 PM ---------- Previous post was at 03:04 PM ---------- here this will help.

  10. #10


    They put a 4.3 in a 94 Z71? Never saw one of Those.

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