Manual Glow Plug Switch Issues

franklin2

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Maybe I'm crazy, but I believe I wired my relay unorthodoxly:

Big hot post tied to the S post (switch/signal, it's what the controller would power), and ran a wire from the small ground post to a grounded switch in the cab. This WONT work for relays that don't have a small ground post (internally grounded), but my logic was that if the wire was ever damaged at worst I'll cook my GPS, and I don't have to run an extra wire for hot runs like you would toggling the S-post. Been fine for many years on an antivandal push button.
That is how Ford wired the glowplug relay on the 87-up trucks with the newer controller. The controller grounded the relay small white wire terminal to activate the relay. That is how most people convert to manual glowplugs on the newer controllers, take the white wire off and tape it, and then run a new wire where the white wire used to be, and wire that to a pushbutton that is tied to ground.
 

BeastMaster

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Then you are now getting your coil power from the main battery rail, just as your glow plugs themselves do.

I don't see anything wrong with that.

Just means your control wire is now active regardless of your key position.

The way it was wired, the key had to be on in order to power the coil that engaged the glow plug power.

By powering the coil directly as you have, you no longer can kill coil power by turning off the key. Your control wire gets shorted to ground anywhere or your button hangs, you can no longer shut down with your key.

Anyway, that's the only caveat I see.
 

franklin2

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Then you are now getting your coil power from the main battery rail, just as your glow plugs themselves do.

I don't see anything wrong with that.

Just means your control wire is now active regardless of your key position.

The way it was wired, the key had to be on in order to power the coil that engaged the glow plug power.

By powering the coil directly as you have, you no longer can kill coil power by turning off the key. Your control wire gets shorted to ground anywhere or your button hangs, you can no longer shut down with your key.

Anyway, that's the only caveat I see.
I read your post and realized I was partly wrong, Ford did use the ground to activate the relay but they also used ignition power for the small + wire to the relay, not battery power.
 

franklin2

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Should there be a inline fuse on the + wire to the Relay?


Goat
In his case with the short jumper wire, no need, the wire is so short it is not exposed to much danger, and the large post that it jumps from should already be protected by the large fusible link or links for the glowplug circuit. That is the beauty of using a ground for the control circuit, if that wire is damaged somehow, there is no danger of a short circuit, just the glowplugs will be on all the time.

On the original later Ford setup, they have a fusible link already that feeds the 12v control to the controller.
 

Old Goat

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Thanks Franklin2,
I have read probably 100 thread,s here and on FTE how to wire the newer style GP Relay manually.

When I read post 18 and then yours, that is when it hit me, "should there be a Fuse?"

I have an 85 & 86 so different set up with the older style Controller and relay.
I eliminated the FW Water Filter. The plug has 3 wires, red hot with key on. Ran it to a momentary Toggle with inline Fuse. Then from Toggle over to relay on Pass. Fender. Connect to post where Purple wire was connected.


Goat
 

TrueBurner

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Sorry for extremely delayed response. I'm sure this has happened to a lot of y'all when you post something and then it finally clicks what you need to do. Turns out it was as simple as replacing the switch in the dash with a new one. Of course it was my last step..... haha Thank you all and hopefully this can help someone else!
 

franklin2

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Thanks Franklin2,
I have read probably 100 thread,s here and on FTE how to wire the newer style GP Relay manually.

When I read post 18 and then yours, that is when it hit me, "should there be a Fuse?"

I have an 85 & 86 so different set up with the older style Controller and relay.
I eliminated the FW Water Filter. The plug has 3 wires, red hot with key on. Ran it to a momentary Toggle with inline Fuse. Then from Toggle over to relay on Pass. Fender. Connect to post where Purple wire was connected.


Goat
That should work fine and be safe. But for your information, that line is already fused with fuse #18. Here's the diagram for a 1986.

You must be registered for see images attach
 

Old Goat

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It didn`t occure to me the wire would be fused for the Water separator when wiring it up.
Guess it is double protected.
That R/Y wire covers a lot of territory.

Goat
 

franklin2

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It didn`t occure to me the wire would be fused for the Water separator when wiring it up.
Guess it is double protected.
That R/Y wire covers a lot of territory.

Goat
That's the advantage of splitting up the electrical with a bunch of smaller fuses. For instance, if you put a small 5 amp fuse in your new glowplug button circuit, if you have a problem in that circuit only, more than likely the 5 amp will blow before the main 15 amp fuse. That helps narrow things down a little bit. With fuse #18, everything is protected, but if you have a problem it's hard to know where to start looking for the problem. It's really bad for the running light circuit. That circuit has one fuse and the wiring goes from the front all the way to the back. So if there is a problem in that circuit, you have to do some guessing as to where the problem is (usually the back bumper area around a trailer plug).
 

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