What am I Missing for WTS Hookup for a 7.3 Swap?

scjarena

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So I swap in a 7.3 IDI into an 86 Ford, which originally had a gas engine. I just want to hook up a basic light to the glow plug controller. I see dozens of diagrams online, blue wire is for WTS. So when I turn my key on, I hook a 12V test light to the blue wire under the hood, to see if I get voltage right after I turn on the key. The GP works perfectly otherwise, I can hear it buzzing when its turned on, just no 12V at the blue wire. Is there something stupid I'm missing?
 

Nero

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I think the blue wire is grounded when the wts is supposed to be on, but I could be mistaken. I swapped the GPC on my truck recently with a genuine Motorcraft, and my light quit working.... Started to check the wire but lost interest.
 

IDIBRONCO

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I think the blue wire is grounded when the wts is supposed to be on, but I could be mistaken.
I think that you're right. I believe that people say to to hook the blue wire to the white wire for manual control with the WTS light working too.
 

scjarena

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Ok, I hook up test light bulb, ground to blue wire, other to +12V and it works. My GP controller always makes a slight buzzing sound until the GP are heated, I hear a click, then it goes quiet. When I hooked the test light, the light went off a little sooner than the buzzing, interesting, but now I know how this thing works. Thanks
 

typ4

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As you found out it is a ground switch. I hooked it to the CEL on my 88 which was a 460 truck, works perfectly.
 

snicklas

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As you found out it is a ground switch. I hooked it to the CEL on my 88 which was a 460 truck, works perfectly.

Now that is funny... I can't count how many times after I've been driving the diesel for a while, that I have gotten in a gasser and turned the ignition on and waited for the CEL to go out to start it........
 

Cubey

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Now that is funny... I can't count how many times after I've been driving the diesel for a while, that I have gotten in a gasser and turned the ignition on and waited for the CEL to go out to start it........

Or get in the diesel and immediately try to start it before the glow plugs fire for the first time that day. Done that before after driving my mom's car earlier the same day
 

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