Glow plug relay keeps going bad
 

Hey guys, I recently replaced my GP's to Beru's on my '84 6.9L. I also replaced my GP relay on the inner fender. I have a switch installed for the GP's because the controller in the back of the engine is junk. After replacing the relay, it worked one time and wouldn't work again so i got a new one and same thing. Anyone have any idea why the relay keeps s*#ting the bed? Is it ok to get rid of the relay and hook the GP's directly to the switch? :-banghead

Use the relay and buy a push button starter switch (You as a controller)LOL.

Check all the wiring on the right fender..... especially the large connectors. They will burnup internally and cause problems. Most just bypass the connectors and solder the wires together.

That would cause my GP relay to go bad after one use?

The relay may not be bad it may just be the wiring....

You need a switch and wiring that could handle 200 amps.
So eliminating the relay is not really an option.

Follow the orange/white wires from the realy toward the engine.
Right before it gets to the engine, there is a connector with about 6 wires in it.
One end has both the orange/white wires in it.
Look at the connector for signs of overheating or distortion.
If yours is as bad as mine was, it will be melted together bad enough you can't get it apart.
Clip all four orange/white wires as close to the connector as you can, then use solder or another heavy duty connection method to splice all of them back together.

I used a copper split bolt and then taped it up good so it did not short out.

The orange/white wires carry the current to the glow plugs, if the connector is bad, no electricity makes it to the glow plugs even though the relay is working.

Thanks for all of your replys, I may need to go a little further into this problem. Ok, when I installed a new relay, I tested for voltage to and from it with a multimeter. When I flip the switch I get a little over 12 volts going to it and 12 volts leaving it going to the GP's which means everything is working properly. I will start the truck using the GP's just one time. After that, if I try to turn on the GP's using the switch, I get a reading of 12 volts to the one side and nothing on the other side? Is faulty wiring going to cause this to happen? Another question....what size wiring sould be used from the battery to the switch and from the switch to the relay? Thanks for your help.

https://www.ford-trucks.com/user_gal...id=120458&.jpg

The two small terminals are what activates the relay.
The bottom one has to have a good ground to it. Usually in stock wiring the wire attached runs over to the fender.

The top purple wire is from the stock controller and is where you should be running the wire from your momentary switch. You need to supply power to that terminal to close the relay. Wire size can be small, the amount of power needed to close the relay is very small.
You never said if you are getting power there after the first start.

The right hand big terminal in the picture is the power from the battery, that wire is AWG 8 to the positive battery terminal from the relay and should always have power.

The left big terminal goes to the glow plug harness.
My wiring there is not stock, that blue fusible link is tied into both 10 AWG orange/white harness wires.

hey dave, I think you just solved my problem. I think i have a few things messed up on that relay. 1- I dont have a larger wire going from the battery to the relay. 2-I have the ground and wire from the switch backwards. Well hopefully tomorrow I can get some 8 guage wire anf fix the damn thing. Thanks for the help!!!!!!

Which terminal the ground and switch are on makes no difference.
The coil that activates the relay terminates in the small terminals.
Just so one is attached to a good ground and the other gets power from the momentary switch.