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

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Real82it
Posts: 11
Joined: Wed Sep 24, 2014 9:08 pm
Location: Albuquerque, nm

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

Post by Real82it »

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?

Real82it
Posts: 11
Joined: Wed Sep 24, 2014 9:08 pm
Location: Albuquerque, nm

Post by Real82it »

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?

Speeder
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Joined: Fri Apr 30, 1999 9:12 pm
Location: 2021 Dodge Durango R/T 2WD, 2008 Colorado work beater, 2003 Dodge Dakota pro-touring project

Post by Speeder »

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.

Hog
Posts: 5025
Joined: Tue Dec 11, 2001 4:00 pm
Location: 1997 Chev ECSB L31 350 1997 GMC Sierra SLE RCSB, Ontario

Post by Hog »

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

Image


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

Bushwacker
Posts: 109
Joined: Wed Jul 04, 2012 4:05 pm

Post by Bushwacker »

Is every year the same pinout?

Hog
Posts: 5025
Joined: Tue Dec 11, 2001 4:00 pm
Location: 1997 Chev ECSB L31 350 1997 GMC Sierra SLE RCSB, Ontario

Post by Hog »

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

Bushwacker
Posts: 109
Joined: Wed Jul 04, 2012 4:05 pm

Post by Bushwacker »

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

Hog
Posts: 5025
Joined: Tue Dec 11, 2001 4:00 pm
Location: 1997 Chev ECSB L31 350 1997 GMC Sierra SLE RCSB, Ontario

Post by Hog »

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

Real82it
Posts: 11
Joined: Wed Sep 24, 2014 9:08 pm
Location: Albuquerque, nm

Post by Real82it »

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

Image


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.

Hog
Posts: 5025
Joined: Tue Dec 11, 2001 4:00 pm
Location: 1997 Chev ECSB L31 350 1997 GMC Sierra SLE RCSB, Ontario

Post by Hog »

And sent.

peace
Hog

Real82it
Posts: 11
Joined: Wed Sep 24, 2014 9:08 pm
Location: Albuquerque, nm

Post by Real82it »

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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