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1995 K2500 4wd low will not shift out of second gear

Discussion in 'GM Powertrain' started by bobm396, Nov 22, 2010.

  1. bobm396

    bobm396 New Member

    1995 Chevy K2500 Light duty with 305 CI engine 155,000 miles. Recently installed a rebuilt E60 auto transmission. Truck shifts properly thru all the gears (1-Overdrive) in 2wd. 2 issues in four wheel drive that were not issues before tranny swap. 1) In 4wd low. Truck will shift from 1 to 2 manually but not by itself and truck will not shift out of 2. It stays right in 2 no matter what rpms are. (What tells the transmission when to shift and is it the same in 2wd as in 4 wd) 2) Switch on top of transfer case that sends power to front end actuator only bumps the switch in 4W low. After looking in the hole the cam is there for both low and high perhaps the switch is faulty or needs to be pusher further in 4W High. This is not a major concern I just thought I would share this in case is would help with the other issue. The transfer case was never taken apart.
  2. mfleetwood

    mfleetwood New Member 1000 Posts

    Welcome to the Club! Unfortunately, I do not know the answer to your question but someone will be along soon who does. Good luck!
  3. NorthportTroller

    NorthportTroller New Member

    Can't wait to hear an answer for this one... eat%20popcorn.gif
  4. murdog94

    murdog94 New Member 1000 Posts

    The Throttle Position Sensor (most prodominate of the sensors when the motor is underload)tells the PCM when to shift the tranny, in 4lo it uses a much different parameters since most people in 4lo are needing all available power and no shifting so they can keep the wheels moving. I know that there is supposedly an override that wont the tranny go past 2nd gear in 4lo because of this. And if you still have the shifter in while you slow down then the tranny will keep itself in 2 all the way to a stop and if left in 2 it will take off in 2nd gear again.
    As to the actuator there is a pretty good chance that is shot which isnt uncommon if you only have 4lo.
    1 person likes this.
  5. bobm396

    bobm396 New Member

    murdog 94 thanks.....Good information. Understanding how it all works is the first step to a repair.
    First problem solved.....Replaced the front end actuator switch thats on top of the transfer case. ($21.00 Napa)
    Now when the "cam" comes up in the transfer case and bumps the switch it is sending 12v to the front end in both 4W High and 4W Low. Will take your advise and look into the "Throttle Position Sensor" tonight..........We are gaining on it.

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