Engine and transmission swap

1999 GMC SONOMA
150,000 MILES • 4.3L • V6 • 2WD • AUTOMATIC
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WESTERNREACH
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Hi, would a 2002 GMC Sonoma 2wd extended cab pickup 4.3. Liter engine and transmission fit into a 1999 GMC Sonoma 2wd regular cab pickup 4.3 liter?
I know the 1999 has an EGR Valve, whereas the 2002 doesn't.
What would I have to swap out? PCM? Wiring harness?
Thank you
Feb 3, 2019 at 5:41 PM
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ASEMASTER6371
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Good morning,

Yes, you will have to swap out the harness and all the sensors including the PCM. If you do not and the EGR connection has nowhere to go, then you will have many codes set for the system since it is missing.

Roy
Feb 4, 2019 at 3:51 AM
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WESTERNREACH
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Hi Roy, thanks for the reply. Do you happen to know if the harness would have to be cut and spliced, or is it something to just unplug and plug in? In other words would it be just the harness in the engine compartment or would it be all the harness into the passenger cabin including the fuse box?
I would (theoretically) have the whole donor vehicle (2002 GMC) at my disposal, so when swapping the motor and transmission would it be safe to assume, I can unplug the engine harness, PCM and just re-plug it into the 1999 GMC?
Thank you,
Steven
Feb 4, 2019 at 11:17 AM
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ASEMASTER6371
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You will need the harness into the passenger compartment. The complete harness.

Roy
Feb 4, 2019 at 12:58 PM
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WESTERNREACH
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Hi Roy,
One more question for further clarification...Will the "complete harness" be just up to/behind the fuse box itself?

Not the harness under the dash throughout the passsenger cabin, (interior lights, speedometer, radio, etc. etc.) ? I would imagine that part of the harness can remain? Thank you, Steven.
Feb 4, 2019 at 7:29 PM
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ASEMASTER6371
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It will include the fuse block and the connector up to the dash board. You will see when you remove the harness from the donor truck.

Roy
Feb 5, 2019 at 2:00 AM