Wiring harness swap

Tiny
WORMY14U
  • 2002 FORD MUSTANG
  • 90,000 MILES

Will a 2002 Mercury Grand Marquis main wiring harness fit my car. My car is the GT model.

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Wednesday, September 13th, 2017 AT 7:42 AM

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Tiny
CARADIODOC
  • EXPERT
  • 28,976 POSTS

Those are two totally different cars. The harnesses will not even be close to the same. You did not list the engine size, transmission type, what problem you are trying to solve, or which of the dozens of harnesses you're looking at. All those things need to be considered when looking for a replacement harness. The options the car came with also affect how the harnesses were built and the plugs that were used. The only time we replace an entire harness is when one was crushed in a crash, or destroyed by fire, and repairing individual wires would be too time-consuming or impractical.

Be aware too that if you try to buy a new harness from the dealer, Ford rarely makes parts available for their cars that are over three years old. When you can still get a harness, large ones can easily cost from $800.00 to $1,200.00. A used one from a salvage yard is the better choice, but if you suspect your harness has a corroded splice, which is due to age, remember the used one you get from a salvage yard is just as old and can have the same problems.

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Wednesday, September 13th, 2017 AT 3:34 PM
Tiny
CARADIODOC
  • EXPERT
  • 28,976 POSTS

"Someone cut the wires before the connector that goes to coils, fuel injectors, I think cold air intake, alternator etc. Can you show me how the wires the color and hole it goes in it is a 42 pin but has I think 32 wires it is a Mustang gt 2002 gt 4.6 engine I never did schematics so a picture would be great. I am going to read and try to learn but need to fix car faster than I can learn. Please help.

If you post replies back to the link you get in an e-mail we can keep this conversation going between us.

It sounds like you are going all the way back to the engine computer. I hate to admit it, but you may have a project that is better handled by replacing the harness. While they are real expensive to buy a new one, this is something the salvage yards have very little call for, so they are likely to not charge very much. You might offer them fifty bucks if they will remove for you the exact one you need. Fifty bucks is better than letting it be crushed when they get rid of the car. Also consider finding a pick-your-own-parts salvage yard. If you are anywhere between Ohio to southern Georgia, and now even in Texas and a few other states, do a search for "Pull-A-Part" and see if there is a yard near you. Their yards are very clean and well-organized. People are friendly and they have real good prices. You pay your buck, take your own tools, and you can spend all day there. That gives you the opportunity to see what it takes to get the old harness off, and if you want to go through that much work on your car.

The alternative is to find replacement connectors and splice them to the car's wires. Every auto parts store has a pile of books showing almost every connector for every car model. They come with about six inches of wire. The problems are this is the more expensive way to do it, and those wire colors rarely match the originals. Most factory wires are a solid color with a "tracer", meaning a stripe, of a different color. The replacement connectors usually come with generic solid-color wires. You just match up the locations, when you have the old connector you are removing. When you have just a bunch of wires hanging there, you are better off snipping your own replacements at the salvage yard. That way you will get the right connector for the application, with the same color wires. Then it is just a matter of splicing the wires together. Always solder them, and never use electrical tape to seal the splices. That will unravel into a gooey mess on a hot day. Use heat-shrink tubing with the hot-melt glue inside. That will seal out moisture.

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Thursday, September 14th, 2017 AT 1:40 AM
Tiny
WORMY14U
  • 2002 FORD MUSTANG
  • 90,000 MILES

How do you remove main wiring harness? My car is the GT model.

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Wednesday, September 20th, 2017 AT 11:36 AM (Merged)
Tiny
STEVE W.
  • EXPERT
  • 4,160 POSTS

Which side body harness or engine harness? Those connect at the bulkhead connector.
Engine side you start by disconnecting the battery, then label each connection as you disconnect them. I like to use painters tape and follow the OEM wiring numbers for the connector. Do not forget that the transmission harness is part of the engine side harness.

Body side is a real bear as you need to strip out the entire interior all the panels, roof liner, carpet, seats, dash.

Might I ask why you want to remove the harness? Repairing a damaged area is much easier.

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Wednesday, September 20th, 2017 AT 11:36 AM (Merged)
Tiny
RANDY ELKINS
  • 2002 FORD MUSTANG
  • 4.6L
  • V8
  • 2WD
  • MANUAL
  • 90,000 MILES

My car is the GT model. Someone cut my wires before the connector on the main wiring harness that control fuel injectors coils that are one for each plug cold air intake, also plugs in to alternator and other things. Can I see a diagram or something showing which wire goes in each hole? It is 42 pin connector but only like 32 are used on the passenger side coming out of firewall. At top of firewall is cut before that connector. Please help! I really cannot read schematics showing the color wire to each hole. Would help a lot if you can help.

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Wednesday, September 20th, 2017 AT 11:37 AM (Merged)
Tiny
STEVE W.
  • EXPERT
  • 4,160 POSTS

Could you take a picture of what was cut off and post it here? I am not sure if you mean they cut off the connectors at the sensors or the bulkhead connector or somewhere else. There are numerous sub harnesses used so it would be very likely you would not need to change out the entire harness, just the section(s) that are damaged.

Overall you would be better off to go to a salvage yard or online and see if you can find an intact harness and use it. Even if you have to spray the connectors with cleaner it would likely take less time.
Some of those wires are very sensitive and a splice could alter a signal enough that it will not run.

For diagrams you can try http://bbbind.com/tech_database.html
Make sure you select wiring diagrams.
Then select the ones you need. There are something like 45 files, most have between 1 and 20 pages each.

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Wednesday, September 20th, 2017 AT 11:37 AM (Merged)
Tiny
WORMY14U
  • MEMBER

Before this connector

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Wednesday, September 20th, 2017 AT 11:37 AM (Merged)
Tiny
STEVE W.
  • EXPERT
  • 4,160 POSTS

OK, Follow that harness out to the next connector and then compare it to the chart to see which harness section(s) are the damaged ones. Then you can look up the correct harness diagram on the above link.
I doubt you can still get the harness through Ford but with the part number(s) you can call them and search online.

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Wednesday, September 20th, 2017 AT 11:37 AM (Merged)
Tiny
WORMY14U
  • 2002 FORD MUSTANG
  • 4.6L
  • V8
  • 2WD
  • MANUAL
  • 90,000 MILES

Someone cut the wires before the connector that goes to coils, fuel injectors, I think cold air intake, alternator etc. Can you show me how the wires the color and hole it goes in? It is a 42 pin but has I think 32 wires it is the model. I never did schematics so a picture would be great. I am going to read and try to learn but need to fix car faster than I can learn. Please help!

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Wednesday, September 20th, 2017 AT 11:37 AM (Merged)
Tiny
2CARPROS KEN
  • ADMIN
  • 11,727 POSTS

We do not have pictures but we do have colored wiring diagrams so you can see what goes where. Here are the diagrams (below):

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

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Wednesday, September 20th, 2017 AT 11:37 AM (Merged)
Tiny
WORMY14U
  • MEMBER

I have never read, but I know mine has 32 wires coming to it its 42 pin and 32 wires. Here is picture and a partial picture I think these wires are right.

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Wednesday, September 20th, 2017 AT 11:37 AM (Merged)
Tiny
WORMY14U
  • MEMBER

And the red is hole 42 red and white 41. The red beside black 34 black 35 and grey red 38 I am positive white with blue 39.

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Wednesday, September 20th, 2017 AT 11:37 AM (Merged)
Tiny
2CARPROS KEN
  • ADMIN
  • 11,727 POSTS

Yes, that can change colors going through a bulk head connector like that. More pictures further down the harness would be better too.

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Wednesday, September 20th, 2017 AT 11:37 AM (Merged)
Tiny
RANDY ELKINS
  • MEMBER

I am no good at reading schmatics is there and way you could help me in reading them or maybe draw and say eactly where it goes I know one red wire connects to 6 I think other red wires you are very helpful to me I am on disability blind yes you got it right 20 400 vision so my wie can tell me colors but can't tell me this wir shetells me ad if I know what color to were this color connects to that's were I am confused never done so if you could help her out I would be very grateful I have never read schematics HAHA never read nutn so any help you can give me showing wire to what hole be treat

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Sunday, September 24th, 2017 AT 1:11 AM

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