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1997 GM 3500 5.7 to 7.4 conversion - fuel injection wiring?
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Post 1997 GM 3500 5.7 to 7.4 conversion - fuel injection wiring? 
Hi.

I have a 1997 Chevrolet 3500 4x4 with a 5.7 and a 4l80e.

I found a low mileage 2000 7.4L motor with computer and wiring harness for sale.

I bought the motor and am in the process of installing it.

the wiring harness from the donor motor is not in good shape, so I would like to use as much of my stock harness as possible. As I compared the 2 harnesses, all the plugs except for the fuel injection connector look to be the same.

I was wondering if I can just cut the 5.7 fuel injection connector off and wire in the 454 connector?

Both have the standard injector 1-8 colored/striped wires, so I think I can match and wire those directly?

My main question comes with the solid pink wires. The original 5.7 harness has a solid pink wire 3 into 5 junction, and then 3 individual pink wires. The 7.4 harness has only 2 solid pink wires going to the fuel injector harness plug.


1. Anyone have any idea how I wire the original 5.7 pink wires to the 2 pink wires on the 7.4 connector?
2. Any other wiring issues I will run into trying to use the 5.7 harness on the 7.4?
3. Any links to wiring diagrams?

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Found wiring diagrams for the 5.7 and 7.4. They look essentially the same. Seems the pink wires are common 12v wires? I can just use any 2 on the original harness and connect them to the 2 on the 7.4 nearness connector?

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If I'm not mistaken it's negative switched. Those pinks are actually +12, not ground. They should be fine to wire willy-nilly, but you will want to make sure the other wires to the injectors go to the correct cylinder or you're not going to be very happy with the result.

No idea if he still posts here or not since this board seems to be going quiet, but Lextech collects wiring diagrams for Chevy trucks.

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Here is the wiring schematic for the CSFI poppets of an L30/31 305/350, its the same for the L29.




As well as PCM connector colour, the exact pin, and the GM wire colour code.

Cylinder - Connector Colour- Pin#- Injector Harness Colour Code


1 - Red - 3 - Black
2 - Red - 11 - Light Green/Black
3 - Red - 32 - Pink/Black
4 - Red - 31 - Light Blue/Black
5 - Red - 15 - Lack/White
6 - Red - 16 - Yellow/Black
7 - Red - 12 - Red/Black
8 - Blue - 5 - Blue/White

If you PM me a working email address, I can send you a 1997 or 2002 Express van pinout/wiring assignment diagrams.

peace
Hog

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Is every year the same pinout?

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Bushwacker wrote:
Is every year the same pinout?

The injectors pinouts so far as colour coding are the same from 1996-2002 for the Vortec engines.

Go check for yourself, if you must.

peace
Hog

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Im taking csfi off & changing the intake & wasn't sure witch wires went to witch injectors, not sure the year of the engine or harness is why I asked if all vortec's were the same

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Bushwacker wrote:
Im taking csfi off & changing the intake & wasn't sure witch wires went to witch injectors, not sure the year of the engine or harness is why I asked if all vortec's were the same

Without checking, I'm saying that you should be safe if you just follow the colour coding so far as the injector harness is concerned. If you require other pinout info other than the injector harness, I would 100% check as there are sure to be differences between 1996, 1997 and 1998-2000 blackbox and of course the 2001-2002 0411 L31 setups.

peace
Hog

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Hog wrote:
Here is the wiring schematic for the CSFI poppets of an L30/31 305/350, its the same for the L29.




As well as PCM connector colour, the exact pin, and the GM wire colour code.

Cylinder - Connector Colour- Pin#- Injector Harness Colour Code


1 - Red - 3 - Black
2 - Red - 11 - Light Green/Black
3 - Red - 32 - Pink/Black
4 - Red - 31 - Light Blue/Black
5 - Red - 15 - Lack/White
6 - Red - 16 - Yellow/Black
7 - Red - 12 - Red/Black
8 - Blue - 5 - Blue/White

If you PM me a working email address, I can send you a 1997 or 2002 Express van pinout/wiring assignment diagrams.

peace
Hog


PM sent with email address. Thanks.

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And sent.

peace
Hog

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Fired the truck up yesterday. Wiring in the 7.4 fuel injection plug to the 5.7 harness worked great. Thanks for the help.

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