95 gmc sierra tranny slip?

Discussion in 'Open Discussion' started by Tman, Feb 15, 2014.

  1. Tman

    Tman Guest

    how yall doing today. I have a 1995 gmc sierra k1500 350 5.7 and I have a lil problem with my tranny. when I put it in drive it runs fine. first gear goes good but then second gear doesn't do so well. when I hit about 35mph it revs its self. kinda like I just put it in neutral and it just revs up. but if I slam on the gas I can feel 2nd gear go back on but im already peeking 4500rpm and you can feel the gear hit and miss. and then it wont downshift. so basically im only able to go 30 and if I try to go over 30 it just slips and revs till I go back under 30-35mph. all other gears work fine. but its just second.. I was told that it was just rebuilt when I bought it witch was about 40000 ago. any ideas? thank you
     
  2. billr

    billr wrench

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    No trouble-codes set? Even if the CEL isn't on (and is known to be working OK at start-up!) have a code scan done with a scanner that can see trans codes and pending codes. Since this is a '95 it may be OBD1 or GM's "OBD1.5", not so easy to get a scan, but worth finding a way to do it; especially if you intend to keep and maintain this truck for a while.
     
  3. Tman

    Tman Guest

    I did a check and all that's out is the o2 sensor because its straight piped. is there anything else?
     
  4. billr

    billr wrench

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    Okay, a couple of thoughts...

    If you cut-and-paste your original post into the "Transmissions" forum it might get attention from the trans experts sooner. Do you know what trans this is? I'm thinking either a 4L60E or 4L80E, but if you know for sure, that will help. I find it very, very hard to believe there are no trans codes set. By '95 the PCM was monitoring engine speed, trans input speed (turbine speed), vehicle speed, and gear commanded. It correlates those and if any clutches are slipping more than or longer than normal, various codes are set. Virtually any abnormal trans behavior results in a code, even some problems that aren't apparent to the driver. Point is, was the code scan done with a high-end scanner that can see all codes? Was the scan done recently, since the trans problem has popped up?
     
  5. Tman

    Tman Guest

    but I no my shop teacher has one. but I have the little key that just crosses the two and it just blinks. I will try to post it to the trans section. oh and the tranny type is 4L60. thankyou
     

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