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Engine harness swap

Tiny
HD2424
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 212,000 MILES
My truck listed above 1500, had a bad engine harness and I got one off eBay from a 2004 Chevy Silverado1500. I noticed that the neutral safety switch on my 2003 Chevy Silverado 1500 is different mine has one big plug and one smaller plug going into neutral safety switch. The one I got off eBay has one big plug. My question is can I just get the neutral safety switch for the 2004 and put on my truck would it work?
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Wednesday, November 10th, 2021 AT 12:53 PM

19 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

They look like the same mountings.

I attached pictures of the two. Tell me which one you have on the truck.

It looks like you are good to replace with the one that connects to your harness.

Roy
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Wednesday, November 10th, 2021 AT 2:08 PM
Tiny
HD2424
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https://www.2carpros.com/images/question_images/431039/original.jpg
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Wednesday, November 10th, 2021 AT 2:16 PM
Tiny
HD2424
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https://www.2carpros.com/images/question_images/431040/original.jpg
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Wednesday, November 10th, 2021 AT 2:17 PM
Tiny
HD2424
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The first picture is the one with one plug that’s from 2004 engine harness.

The second picture is what’s on my truck now it has two plugs for neutral safety switch.
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Wednesday, November 10th, 2021 AT 2:19 PM
Tiny
HD2424
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  • 191 POSTS
Please let me know and thanks a million. I just don’t want to waste my money and time if it doesn’t work. My ECU is programmed to my VIN not sure if computer recognized it looks like they just combined the two plugs to one on 2004.
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Wednesday, November 10th, 2021 AT 2:23 PM
Tiny
ASEMASTER6371
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Those are the exact images I already posted for you.

Yes, it will work.

Roy
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Wednesday, November 10th, 2021 AT 2:32 PM
Tiny
HD2424
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  • 191 POSTS
So, if I get the neutral safety switch for the 2004 with one plug and install in place of the two-plug switch on mine it should work?
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Wednesday, November 10th, 2021 AT 2:43 PM
Tiny
ASEMASTER6371
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That is correct. As I stated it will work.

Roy
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Wednesday, November 10th, 2021 AT 2:48 PM
Tiny
HD2424
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Thanks bud.
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Wednesday, November 10th, 2021 AT 2:57 PM
Tiny
ASEMASTER6371
  • MECHANIC
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You are welcome.

Always glad to help.

Roy
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Wednesday, November 10th, 2021 AT 3:00 PM
Tiny
HD2424
  • MEMBER
  • 191 POSTS
  • 2003 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 212,000 MILES
I have a 2003 Chevy Silverado 1500. I’m changing out my engine harness. I have removed and now labeling the plugs and wires on the replacement before I install. I have labeled every plug except one. It’s a 2 pin black with blue cap it’s about 12 inches down from the oil pressure sensor, cam sensor and ground wire the goes in back of engine up top. See picture
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Wednesday, November 17th, 2021 AT 7:22 PM (Merged)
Tiny
HD2424
  • MEMBER
  • 191 POSTS
  • 2003 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 212,000 MILES
I have a 2003 Chevy Silverado 1500. I’m changing out my engine harness. I have removed and now labeling the plugs and wires on the replacement before I install. I have labeled every plug except one. It’s a 2-pin black with blue cap it’s about 12 inches down from the oil pressure sensor, cam sensor and ground wire the goes in back of engine up top. See picture.

The harness came from 2003 Chevy Silverado 1500
SLT 5.3 4x4. It seems my old harness didn’t have this plug but not sure. I’ve looked at some diagrams where cam sensor and oil pressure sensors and don’t see any other sensor this plug would plug into
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Wednesday, November 17th, 2021 AT 7:22 PM (Merged)
Tiny
AL514
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Hello is this the Extra Cab model and what are the wire colors on the 2 pin connector?
Also this is just a gas model, not gas/ethanol?

From what I can see in the picture, it looks like it might be the knock sensor plug, which is under the intake manifold, unless youve already plug that one in. Dark Blue and Light Blue wires.
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Wednesday, November 17th, 2021 AT 7:22 PM (Merged)
Tiny
HD2424
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My truck is gas extended cab. My knock sensor plug is on driver side I’ve confirmed that. The plug in question It’s 2 wire. I saw online it was a knock sensor plug. On my truck the knock sensor plug is a bigger plug on driver side.
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Wednesday, November 17th, 2021 AT 7:22 PM (Merged)
Tiny
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I know my knock sensor is plugged up could that just be for a different application or is there a knock sensor plug on both sides of intake
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Wednesday, November 17th, 2021 AT 7:22 PM (Merged)
Tiny
HD2424
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This is where my knock sensor plug is located
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Wednesday, November 17th, 2021 AT 7:22 PM (Merged)
Tiny
AL514
  • MECHANIC
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I only see one in the wiring diagrams, but some models do have 2 of them, so it could be that the harness you bought has plugs for both. Are the wire colors for the one you have plugged in the same colors? What are the colors on that plug with the blue clip? If its Dark blue and Light Blue wiring, thats the only sensor I see with those colorings.
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Wednesday, November 17th, 2021 AT 7:22 PM (Merged)
Tiny
HD2424
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Hey thanks for the help you where right light blue dark blue is knock sensor that is the correct plug had it mixed up with another plug.

Thanks a million
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Wednesday, November 17th, 2021 AT 7:22 PM (Merged)
Tiny
AL514
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Awesome, so glad you found the right one, you might have been chasing a check engine light issue for awhile with that one. Happy to help. Have a great day.
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Wednesday, November 17th, 2021 AT 7:22 PM (Merged)

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