1987 GT Convertible - Mystery plug

R82148V

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May 26, 2020
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Hello Everyone!!

I'm new to this forum and excited to be here.
Please allow me to first say a BIG THANK YOU to all the Health Care professionals, First Responders, Essential, Working at home Non-Essential, Warehouse, Moms and Dads workers out there! I hope you and everyone out there are doing well and staying safe?!?

I have a mystery plug that I cant seem to locate in any schematics or diagrams.
This looks like a grey double wire connector (two black w/white wires) right at the ignition coil. Attaching a pic
I have no idea what this goes to. It does ground out if you connect an ohm meter to the plug and Neg battery cable.

Any thoughts?

Let me know if you have any questions, stay safe out there and thanks!
 

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BlakeusMaximus

Still got to try a little lube on my speedo head
Jul 12, 2017
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That's one of the plugs for a diagnostic connector. There should be a bigger brown one somewhere in there too. Right? Its been a while since I had mine hooked up to a diagnostic reader.
 
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R82148V

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May 26, 2020
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That's one of the plugs for a diagnostic connector. There should be a bigger brown one somewhere in there too.
Hey BM,

Thanks for reaching out! There are (3) same looking plugs like the one in the above pic.. A brown connector that is for the hood light, A grey connector (STI) diagnostic port that goes with that bigger diagnostic connector and then there is this one in the pic.. The mystery connector is close to the coil and battery.. When I test it with a mulitmeter, it grounds out..
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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Grounding that plug tests the windshield washer pump.

Very unknown plug as it's purpose isn't documented anywhere. I had a feeling this thread was going to ask about that plug.
 
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BlakeusMaximus

Still got to try a little lube on my speedo head
Jul 12, 2017
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I thought it was the little connector for the diag unit. Never mind. Carry on.
 

R82148V

Member
May 26, 2020
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You're correct!
After you said it was the the windshield washer pump test connector. I did a little research and that is exactly what it is!
It should have 12v when the pump is activated. Thanks everyone for all your time.. !!!!!
1590605251823.png
 

JD08

I love your drawers
Apr 22, 2017
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It's funny how they've learned over the years. Our LX's had an unused plug for the fog lamp, but the 2011-up used a different harness so people couldn't just add them without spending hundreds.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
33,597
9,883
224
Massachusetts
It's funny how they've learned over the years. Our LX's had an unused plug for the fog lamp, but the 2011-up used a different harness so people couldn't just add them without spending hundreds.

Yeah. Can be a PITA.

Wanted to add a heated steering wheel to my Taurus. Bought the heated wheel module, the clockspring, the wheel with heating element, and then went to install it and the wiring wasn't present. I could easily add the heated wheel icon to the touchscreen and program the module with forscan. All stopped due to lack of wiring. Wasn't even easy to integrate. Project dead. :(
 
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