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I need a li'l help with a 4L80

I fixed the ADL conn(ground was disconnected)I retrieved DTC's by jumping A to B terminal. MY Scanner still wont read the codes.:rolleyes5:

anyway,DTC 85 (undefined)and 87 (high ratio)are present,whatever they mean :dunno:no SES light on.

My manual dont lists these codes on the 92,but does on the 93 with 4L80.
 
OK, i went for a drive myself,Owner is out to lunch on this shifting thing.

start from cold,truck shifts 1,2,3 smooth. No overdrive and no TCC lock "period".Engine at 2500 rpm nets only 60 km/hr.(owner was pegging the cruise at 3700 rpm to get to 90/95 km/hr)A mirracle he did'nt blow the mill.He thought it was normal.
Shut it down,wait 10 min,start up again tranny will shift 1,2 and wont go in 3rd.
Keeping it in first gear the tranny will shift to second regardless.

Now what?
 
The code 87 isn't good, sounds like she has seen better days. I would drop the pan on it and look to see if you find much clutch material in there, if you do she needs a rebuild as well as the iso-converter valve upgrade.
 
As the oil and filter had been changed twice recently with the prob present there wont be much debrie to be found i suspect

What do these codes 85 and 87 indicate?
My chilton manual is very skimpy on the AT
 
The codes for the 92 are the same up through 95. 85 is for undefined ratio meaning that the gear ratio it measured from the ISS to the OSS fell outside of the programmed ratio. 87 is for a high ratio basically refferring to high slippage in 3rd or 4th. It sounds like to me that 4th gear has had it which is a known weak area in the 4L80E. First thing to do is get a scanner on it though and drive it. While driving it monitor the calculated gear ratio in 3rd and 4th gear. 3rd should be 1:1 and 4th should be .75:1.
 
From the 91 chevy factory service manual: dtc 85 Undefined ratio ,Code 85 will set if the pcm/tcm's calculations indicate an unexpected gear ratio does not include overdrive. Action taken- set pressure to maximum
DTC 87 shift solonoid "B" stuck off. Code 87 will set ifthe pcm/tcm commands 3rd or 4th gear but a ratio calculation indicates 2nd gear. Action taken-set pressure to maximum.
Check all electrical connectors for bent or pushed out pins, oil contaminationin connectors and check grounds on rear of engine.
 
Acesneights1 said:
3k is way too much for a 2wd 4l80e. Try another shop. That is a 1500-1800$ job. Maybe even less.
Click to expand...
Yea right!,not around here they dont.Its Canada here!Stealing is legal.

Nah, this baby like all else i'm gonna rebuild myself,just need to find out what is acting up.
I pride myself on all fixing done in my own shop,no stealers dipping in my wallet:nonod:
 
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