glow plug relay wiring

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Jan 13, 2010 | 08:57 PM

jakemb

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Joined: Nov 2004

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glow plug relay wiring

This question may have been asked before but couldn't find anything in the search.Is it ok to disconnect both small red wires from the glow plug relay and just have a momentary switch on the dash? I did this today and everything worked fine.While testing the two small red wires I found one has power all the time and the otherhas no power even ifI cycle the key.I unplugged the small contector for the red wires and am just feeding current from the momentary switch.Why does one of these reds have current al the time?
Thanks

Jan 13, 2010 | 09:21 PM

F350-6

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Joined: Mar 2007

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From: Texas

I suck at colors, but there are 2 large posts on the GPR. One is power in from the battery, the other is power out to the glow plugs. The 2 small posts are for key on voltage and a ground signal that activates the relay controlled by the PCM.

You can wire in a switch, but the guage of wire and duty of the switch will vary depending on how you wire it. If you use the GPR and just put the ground signal on the switch, a light duty switch and small wire should do. If you're wanting to bypass the relay and send voltage through the switch to the glow plugs, you'll need a pretty heavy gauge wire and severe duty switch.