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Post Info TOPIC: reprogramming pcm with different rpo codes can it be done?

Veteran Member

Status: Offline
Posts: 91
Date: Aug 8, 2011
reprogramming pcm with different rpo codes can it be done?

... this  car would have to go to dealer for this procedure but i wanted  to know if anyone here had input


hi everyone's my situation

short story .... cavalier (j body) drivetrain replaced with
alero (n body)drivetrain ....the final drive ratio is
different and trac off light comes on.....

question .....can the j body pcm be reprogrammed with the
rpo code to match the n body transaxle final drive

long story ...last year i bought a 2000 cavalier z24
convertible which needed an engine 199k mile 2.4l engine and
4t40e transaxle ....i bought a beat up alero with 120k which
ran and drove good ..being the "smart guy" that i am ,i
changed the water pump and replaced engine and trans as a
unit ,,,, the cavalier ran great .....except .......trac off
light comes on when pcm thinks the trans is slipping due to
programmed cavalier final drive ratio and actual final drive
ratio of alero transaxle

i have the rpo code label and the pcm from the alero ..i
installed the alero pcm in the cavalier thinking that i
could match the pcm to it's original tranaxle and all would
be fixed ...there's a ses light now because the alero pcm is
looking for the #2 cooling fan which the cavalier doesnt
have ...also the fuel gauge is always on empty and srs light

i'm not familiar with the gm pcm programming/reprogramming
procedure a pcm programmed strictly by vin or can
the rpo codes be changed during the procedure ?

thanks for any help .paul


Veteran Member

Status: Offline
Posts: 57
Date: Aug 10, 2011

Unfortunatelly you will find launch not to be able to do so many commond procedures in American based cars. Also coverage over domestic brands is not good at all.

If it is tru that launch is a good overall tool specialy for european vehicles it has tremendows faults in domestic vehicles.

Also tech services really sucks at least in Mexico and what I have read in USA too....

Seems to me that launch is no loger interested in American market or the do not whant to get the customer support at the american style but a chinise style....

Jesus loves you...... I simply do not.....


Status: Offline
Posts: 14
Date: Sep 27, 2011

Launch can not "program" any module in any vehicle Domestic, European, or Asian.  I do believe you need a "J2534 passthru" tool for what you are describing and Launch is "bidirectional". 


Veteran Member

Status: Offline
Posts: 91
Date: Oct 31, 2011

i wanted to update my original post/ question   ... re; transaxle swapped causing  final drive ratio change and computer confusion

i was able to send out the donor car pcm that matches the transaxle  and the good vehicle's pcm ...the gear ratio and other critical info was pulled from the donor pcm and installed in the good vehicle pcm ... (automotive copy and paste)

hope this helps someone


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