Chevy/GMC 6.2L and 6.5L Discussion of Chevy and GMC Trucks with 6.2L and 6.5L Diesel Engines

4L80E problem

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  #1  
Old 07-23-2012, 05:05 PM
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Default 4L80E problem

my trans won't stay out of passing gear. any ideas?
 
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Old 07-26-2012, 02:25 AM
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do you mean that it acts like it shifts into OD but when you touch the gas again, it kicks out? or you don't have OD at all? can you describe in better detail please?
 
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Old 07-26-2012, 04:08 PM
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kicks out when touch throttle
 
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Old 07-27-2012, 11:45 AM
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what kind of vehicle? mechanical or electronic injection pump? is the check engine light on? if so, what are the codes.

my trans had the same problem when i got it. PCM picked up slipped in 4th gear and defaulted to no OD. It also shifted at 2500 rpm from both 1st and 2nd. Also it wouldnt kickdown when I stepped on it, once it got to 3rd, it stayed there until I came to a stop.

Does this sound like you problem?
 
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Old 07-27-2012, 01:26 PM
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no, mine is 93 k2500 mech ip, shifts through all 4 gears, then when i let off throttle i get another "shift" up, i'm thinking torque converter isn't locking, because when i touch the throttle again to maintain speed it "shifts down", unlocks? and doesn't shift up "lock" until i let off the throttle again

---AutoMerged DoublePost---

i have no tach
 

Last edited by steelmanpdx; 07-27-2012 at 01:26 PM. Reason: Automerged Doublepost
  #6  
Old 07-29-2012, 11:08 AM
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I read that the torque converter lockup "hunts" for the perfect conditions to lockup, and that it doesn't take much for it to unlock. You'd have to go with an aftermarket controller or a manual switch to keep it locked up.
 
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Old 07-29-2012, 07:37 PM
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I have manual switch for TCC Lock. Usually torque converter only locks in OD
 
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Old 08-13-2012, 08:16 AM
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Originally Posted by cviola2005
what kind of vehicle? mechanical or electronic injection pump? is the check engine light on? if so, what are the codes.

my trans had the same problem when i got it. PCM picked up slipped in 4th gear and defaulted to no OD. It also shifted at 2500 rpm from both 1st and 2nd. Also it wouldnt kickdown when I stepped on it, once it got to 3rd, it stayed there until I came to a stop.

Does this sound like you problem?
My 4l80 is doing what you just described. I just got the 93 chevy 3500 and have not checked the problem yet. What was the fix for yours?
 
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Old 08-13-2012, 01:38 PM
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every time it would kick out of OD and wouldn't go back in, i pulled over and unplugged the trans computer for about a minute, plug it back and i was good to go. its not really fixed, I ust take it easy when its in OD and it usually doesnt kick again.
 
  #10  
Old 08-19-2012, 02:27 PM
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i think i'm going to put in a mech switch
 
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