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How to make a late model 1996 4l80e work with a 1992 ecm and engine?

Mrollins

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I recently purchased a 1992 k2500 with the 454 and 4l80e. It appears that the previous owner swapped a 4l80e from 1996 into it. It keeps going into limp mode and I think its bc the PROM isnt correct. Does anyone have any advice or knowledge on how to make this set up work properly?
 

WarWagon

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We really need a FAQ on here about swapping transmissions and their differences. Sadly you should simply get a 91-93 4L80E for the most frugal fix.

91-93 4l80e's should be considered a different trans from 94+
 

spdgofast

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Or buy a stand alone computer which will allow you to adjust the line pressures and shift points etc. etc. but will probably cost about $800.00 bucks
 

THEFERMANATOR

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Or buy a stand alone computer which will allow you to adjust the line pressures and shift points etc. etc. but will probably cost about $800.00 bucks
I recently purchased a 1992 k2500 with the 454 and 4l80e. It appears that the previous owner swapped a 4l80e from 1996 into it. It keeps going into limp mode and I think its bc the PROM isnt correct. Does anyone have any advice or knowledge on how to make this set up work properly?
91-93 4x4's have an output reluctor in them, 94+ 4x4's do not. Starting in 94 GM changed and used the vehicle speed sensor in the transfer case, and added in an extra pin to the transfer case switch to tell it when it was in 4 low to correct the shift points. You could possibly get an aftermarket controller to work, but the transfer case speed sensor puts out a weak signsl that doesn't always work to provide dual outputs, and you would still be screwed in 4 low as your 92 t-case has no 4 low output trigger. And then you're up against 91-93 used a completely different epc solenoid that runs at a different frequency and requires a cleaning cycle every 10 seconds. 94+ do not have the required nain pressure accumulator as well as have an extra vent for the new style epc.

You're best bet is to get the correct 91-93 4l80e, otherwise you need to COMPLETELY disassemble the 96 to add in the output reluctor wheel, or change your transfer case, rewire it to use a 7427 pcm, and get a custom prom chip as a 94/95 454 uses high pressure tbi so it's chip won't work.
 
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