1996 swap to 2003 5.3/auto

[468Blazer]

Thought I'd show some steps I took to complete the swap of putting in a 2003 5.3/auto in my 1996 GMC sierra.

Step 1
Found donor vehicle to get engine/trans/wiring/pcm from.


Step 2
Removed the wiring from 03 engine. Sent the wiring and pcm off to Nelson Performance.

Step 3
Removed 5.0/auto from truck. I kept all the factory harness hooked up just for the sake I didn't have a clue yet on what to get rid of and what to keep.


Step 4
Ordered ls mount adapter plates from Car shop Inc. $45.95


Step 5
For fuel rails on intake I ordered from Pure Choice Motorsports. Part # 5800 included 3/8" and 5/16" adapters to -6AN. $34.95
From them also ordered the adapters that connect to fuel filter and fuel return line. Part # 5090. These are 14mm and 16 mm that go to -6AN. $17.95



Then all you have to do is order/make your lines to length with -6AN fittings on each and connect the feed/return lines. I ordered mine premade from jegs.

Step 6

For temp gauge I ordered the adapter from 12mm x 3/8 pipe from Street & Performance. $18.50. This was put in place on passenger side head.

For oil pressure sender the adapter above the oil filter was taken off and tapped.


Step 7
Swapped power steering lines from old 5.0 pump to 5.3 power steering pump.
Swapped the tranmission lines to cooler from old to the new.

Step 8
Installed the 03 5.3/auto trans.


Only had to move the tranny mount a bolt back and driveshaft was fine.


Step 9
Received wiring/pcm tune from Nelson Performance. Wired up engine/trans.


Step 10
Mounted TAC Module for drive by wire gas pedal in place of factory cruise control location.


Step 11
Hooked up all lines, fuel, etc. Factory fuel pump was fine.

Step 12
Double checked everything to make sure its hooked up correct.
Turn the key and........... nothing. lol
Had to connect purple and yellow wire in factory harness that goes to neutral/safety switch. Hooked up to wiring to go through factory ignition.





This is just a start tonight. I'll finish the swap pics later.

[Zdahl_Chevy23]

about how much did nelson performance charge you to rework the harness and pcm? im looking to do this swap to my 96 but i just wanted to get all my ducks in a row first

[GasGuzzler]

Will the stock 5.3 oil pressure sender behind the intake not work? Could you install the 5.0 sender in the stock location back there if not?

[RedHeartbeat]

So many different types. The Gen3 has something like a 14mm thread while the 96 has a 3/8npt or 1/8npt thread, an adapter would be needed to put the OBS sender in the Gen3 oil pressure port location. The 96 dash oil pressure gauge is still analog not digital from the PCM, isn't it?

[GasGuzzler]

Not sure. I'd have to look that one up.

[468Blazer]

As far as cost the reworked wiring $450, tune $375 and ls1 efan wiring harness think was $100.
If one had a good pin out of the wiring you could save that money yourself. Just from experience if your getting your wiring reworked make sure your wiring was in good shape and everything working prior to sending it off.

Only thing I wished I had done was had the wiring to the pcm longer to mount the pcm somewhere else but it worked out ok the way it was.

I did have the adapter to mount the 96 oil pressure sender in back of intake but some said the 03 pcm needed oil pressure for the pcm and some said it didn't. I haven't unplugged it yet to see if it makes a difference, so I just kept both sensors in.

[GasGuzzler]

An 03 doesn't "need" the oil pressure switch for anything but the gauge/warnings. Just going over possible swap candidates in my head. Since I have access to the schematics, I'd probably do the harness myself.