engine swap 99 gmc sonoma 4.3

Carl59

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#1
Make
gmc
Model
sonoma sis 2wd
Year
1999
Miles
?
Engine
4.3 liter v6
hello,
have an opportunity to do a motor and transmission swap on a 1999 GMC Sonoma 2wd (4.3 liter) short bed pickup with a 2002 GMC sonoma 2wd (4.3 liter) extended cap pickup (this would be the donor vehicle)

i know the 2002 doesn't have a egr valve, but the 1999 does.

other than that what are the other obstacles that i may come across?

am i best to look for a direct swap vehicle?

thank you in advance
 

grcauto

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#2
You may be able to swap out the intakes and be OK. You'll need to be sure the gear ratios are the same between the two as this will allow you to do the swap without transfer of the modules.
 

Carl59

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#3
thanks for the reply, if i were to swap out the pcm and its harness, would there be a lot of wire splicing? or is this an unplug and reconnect situation?
 

grcauto

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#4
You would probably have to program the PCM, TCM and most likely the BCM or theft module. They all have to have the correct VIN numbers.
 

Carl59

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#6
As far as swapping out the modules is concerned, does anybody know as to what extent the wiring harness has to be removed? In one whole piece? (Unplug old and plug in New) ? Or cutting and splicing a lot? (Keep in mind I'd be swapping motor and transmission) Thank you in advance
 

grcauto

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#7
If the modules are the same series they should be OK to switch out without doing the wiring. I would want the donor vehicle at hand so that you will be able to yank whatever you need to make it work.
 

billr

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#8
Have you found any obvious differences in the harnesses yet, especially at the PCM and trans? You know, things like different type or number of connectors?
 

Carl59

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#9
If the modules are the same series they should be OK to switch out without doing the wiring. I would want the donor vehicle at hand so that you will be able to yank whatever you need to make it work.
Hi, thanks for the reply...I plan on having the donor vehicle side by side, just not sure if the depth of things to change would require extensive swapping of wiring, (I.e. Harness throughout the interior fusebox, and dash wiring- which is something I'd rather not get involved with)
 

Carl59

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#10
Have you found any obvious differences in the harnesses yet, especially at the PCM and trans? You know, things like different type or number of connectors?
Hi, thanks for the reply, I have not (due to the exorbitant amount of snow here, trying to get a jump on it when it finally melts enough to get it into the shop)

Are there any other ways to discern differences.? (Via shop manuals or the like) I'm sure connectors are different on some sections of the harness. Egr valve delete on the 2002 is bound to present some problems, just would like to find out if it's an easy thing to deal with.
 

grcauto

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Hi, thanks for the reply...I plan on having the donor vehicle side by side, just not sure if the depth of things to change would require extensive swapping of wiring, (I.e. Harness throughout the interior fusebox, and dash wiring- which is something I'd rather not get involved with)
Making sure the modules have the same connectors and same pins populated and it'll be fine.
 

Carl59

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#12
Making sure the modules have the same connectors and same pins populated and it'll be fine.
Thank you. Do you think the transmission would be the same (for a direct swap)?
1999 is standard cab, 2002 is extended cab.