Looking for advice on Glow Plug Relays

[ClockworkSkin]

I recently burned through a set of glow plugs in a week. Without getting into the backstory, here is where I'm at.

New set of plugs installed right now. New terminal ends on all 8 wires. The wires are currently disconnected. I want to make sure that everything is good to go with the electrical system before I plug the new set in and start it.

I tested the relay with the leads disconnected and I'm getting 24v on the top and bottom posts of the relay. I had the post with the blue wire connected to ground to test the relay so I could get a good read on my multimeter. I also tested the terminal ends (that plug on the ends of the GPs) and got 24v there. Is this a bad relay? Will I get a different voltage if I hook the terminals up? I'm afraid to test because I cannot afford to burn through these plugs at $70 a set.

 

[doghead]

All you describe is normal.

Without your "backstory", we can't help you figure out what went wrong to cause them to burn out.

 

[ClockworkSkin]

The backstory is the original set of glow plugs went bad. I replaced them all but one. I put 7 new ones in and within a week burned through them. Doghead, you actually commented to me NOT to run the truck until they were all replaced. I missed that post until I started having problems a week later. I kicked myself. Thank you for all of your advice by the way, it's priceless.

Right now, I'm thinking that I'm thinking that the plugs were my only problem, I'm just afraid to plub them in and test them.

24v at the bottom post and at the GP terminal ends is what should be there? If I hook them up, and turn the key forward to charge them, should the volt be 12v? Should it ever spike above 12? I've been reading all night and I'm getting confused.

 

[doghead]

Your last comments are correct. The 24 volts will drop in a second or two,to 12V, with 8 good glow plugs connected.

BTW, if you need to start a truck that you cannot change all 8 Glow plugs on, you can disconnect the 24V supply, and connect to the relay to the 12V buss(diamond shaped with 2 studs) and you will not have the other plugs go bad(because one or more is bad). There are other compromises with this set up so, please understand them first, if you want to do this.

Also, Sorry I did not remember you and your situation.

 

[ClockworkSkin]

Ok so just so I have this clear. I'm going to hook up all 8, turn key to run position, and test at the GPs. At that point I should see the voltage fluctuate from 24 to 12 correct?

No worries about forgetting the first, with as many questions as you answer on this board, you should be given a medal.

 

[doghead]

You are correct! (you can measure the voltage at either the top or bottom of the relay(does not matter) Good luck!

 

[ClockworkSkin]

Well once again you were spot on. I plugged everything in, turned the key, read the voltage and it was pretty steady at 12v. This makes sense because my original bad set of glow plugs was just old. There wasn't anything else wrong with the electrical system. I have it started and idling right now.

Thank you again.