12V glow plug wiring question..

[Gator6x4]

You need to install a relay. Relays carry heat loads better than switches. If I understand what you are saying you are wanting to run a hot wire to the glow plugs keepin them hot all the time. This could cause a catastrophic engine failure if a glow plug melted from constant heat and broke and fell in the engine.

Glow plugs do not need to be engerizered more than 8-10 seconds at a time, not constantly.

 

[Industrial Toys]

That wasn't my take on it at all. He just wants to bypass his "suspected" bad keyswitch with another stand alone switch.

 

[atsah]

That wasn't my take on it at all. He just wants to bypass his "suspected" bad keyswitch with another stand alone switch.

Bingo..

I have a test light and a DVM. I removed the plugs and ohmed them out, .07ohms on each one, so I think they are good. There is a light on the dash but no relay at all in the circuit. The plugs are connected with a buss bar, the power wire comes from the ignition with a tap to the dash light on a 5 amp fuse straight to the furthest glow plug. I get about 9V at the glow plugs but not all the time. The glow plugs look new and heat up fast if I put 12V to them and take it away quickly so they are good.

 

[atsah]

I suggest you approach this in an organized fashion. Do you have a 12 volt test light like this one? Less than $10

Any chance you have a wiring diagram? If you don't, suggest you post photo of the glow plug side of your engine.

Glow plugs could be wired in series or parallel and it makes a big difference in determining what could be wrong.

Usually, there is a Glow Plug indicator wired in series or parallel with the GP's. While the indicator is giving the owner info, it is also moderating the current flowing to the GP's. The indicator will be a tiny open coil of wire that will turn red as you heat the GP's

GP manufacturers advise against applying 12 volts to their GP's and if you do so you risk part of the GP tip breaking apart inside the engine and the consequences of this can result in a destroyed engine.

On older engines, often GP's don't work because rust has destroyed their ground to the engine block.

Dave M7040

I have the test light and DVM see above post, I don't see any tiny open coil. I do have the wiring diagram..

 

[Industrial Toys]

I have a Fluke DC clamp meter (Uses Hall Effect Technology). It's great for troubleshooting stuff like this, albeit a bit expensive.

I would use a HD starter type push button switch and avoid the relay provided the switch can handle the current. Why make things more complicated?

 

[atsah]

Does the top of the plug itself get warm after you turn the glow plugs on? I just put an electronic temp gauge on the top of the plug and the temp did not change..

 

[standup616]

Burnt connection in your switch if your key switch controlls it all. Your battery should have 12.7 volts, you are only getting 9 volts on the buss bar if you cant find a resistor or have a deeply discharged battery. That 9 volts may only be fractions of an amp, not enough to feed the plugs load. If there is not a special position in the key switch to activate the glow plugs (buss bar) then would there would have to be a relay and some sort of controller in there that would operate the relay to keep them from being on full time. The glow plug conroller would have some sort of timer that ran the glow plugs for a predetermined time based on the engine coolant temp.

 

[Industrial Toys]

I'm thinking that whole thing should see a rise in temperature with the current that should be going through there.

 

[atsah]

I'm thinking that whole thing should see a rise in temperature with the current that should be going through there.

I wonder if I have a grounding, maybe I should put a ground on each one and see if it gets hot..

 

[Industrial Toys]

It's why the element in the dash was such a good, simple and engenius idea. Presumably it was in series, and if it glowed, you knew the plugs were getting warm too.