Glow Plug Circuit (do I need a resistor?)

[rszimm]

I'm fixing up an old Ford CL65 skid steer. Most all the non-essential wiring / gauges / switches were stripped out of this thing including the original ignition switch and the entire glow plug circuit (old owner just squirted a bit of starting fluid into the air filter whenever he wanted to go). From what I can tell from the schematic the ignition switch turns counter-clockwise to engage the glow plug circuit. When the indicator "glows red", you then turn the key clockwise and start the engine. The glow plugs are the pencil type wired in parallel. Here's an image of the ignition switch schematic and this mysterious "glow indicator": . So here's some questions:
1. Whats happening inside the ignition switch with respect to terminals #19 & #17? (the extra wire off of #17 goes to the plugs). I'm thinking that in "pre-heat" mode terminals 30 and 19 are connected, but then what's #17 for?
2. I was going to bypass the indicator completely. I don't really see it as particularly useful, but it occurs to me that it may be providing some resistance and thus dropping the voltage down below 12V. Can I delete this indicator?

Just some additional info: There is no block mounted "block resistor" in this. The wire you see coming off terminal 17 goes directly to the plugs. They're all wired in parallel. I pulled them and they all seemed burnt, so I just ordered some NKG Y-107V plugs

 

[Fuddy1952]

Hopefully you'll get a better answer than mine because I'm only guessing.

I would think the preheat is just a simple thermal device so with ignition switch switched over it supplies power to glow plugs until preheat device opens.
On NKG site those plugs specs says 10.5v which to me should be ok on 12v, but you may want to call them.
Here's the # to NKG...888-800-9629

Me, I would want to put it back stock if not too expensive.

 

[Industrial Toys]

I don't really know what you have.

What is the indicator. A lamp or a heating element? Some Bolens type tractors had a dash mounted Element in series with the glow plugs. It would tell you what was happening. If it glowed hot, you knew the glow plugs were as well.

Others (like my Steiner) have a light, that is on a timer, but has nothing to do with the glow plug circuit. It's just a timer for the operator to watch.

Then, My mule has a timed glow plug curcuit that has an indicator light to show when the glow plugs are on and off (ready to start) and it does this every time, whether you need them or not.

So, there are a number of different systems in use.

Generally speaking, a cold 12 volt battery has limited power and reducing the glow plug power with a resistor that drains your battery and heats the great outdoors is not really a great idea.

 

[WranglerX]

Appears to be signal light assembly... Maybe a "glow lamp"...

Note reference to CL65 in product description...

NH4304 Glow Plug Light (Signal) Assembly---Replaces SBA185306101

Does it look similar to this?...

Device could also be a inline resistance for glow plugs... Just a guess here...

Dale

 

[Industrial Toys]

It's actually a brilliant, simple, almost primitive idea. You are loosing a bit of stored energy needlessly, but knowing exactly what is happening with your glow plugs is probably worth it.

 

[PILOON]

You can wire directly with a HD switch (curent is high) and simply count off a few seconds and repeat if not successful.
(I knew one guy that simply had the 2 wires in his cab and simply held them between his fingers and counted)

Generally the plugs should be in parallel and grounding is via the engine block.(you will note all the plugs will be on one HD wire or buss strip)

Various timing mechanisms are generally incorporated to eliminate human error but the simple switch can do the job.
Just don't power up too long as U can burn out those glow plugs. Start off with, say 8-10 seconds and repeat if necessary or add a few more seconds next time.

 

[Fuddy1952]

I had a VW Rabbit diesel pickup in '82, 4 cylinder, and glow plug light would be on about 10 seconds then off, ready to start.
When it got hard to start over the years I used an inductive ammeter on each glow plug wire to see which was open (bad ).
Then I realized all I had to do was turn key on then off 2-3 times cycling plugs on then quickly feel them. Warm ones ok...cold were bad.
On that one I would at least wire in a light, that #17 to glow plugs , wire light there to ground. That way you know they're getting power and how long they're on.

 

[rszimm]

So I do not know what is supposed to be there. Nearly all the electrical was removed from this unit. The glow plug circuit ended with a cut wire. The ignition switch was replaced with a cheap key switch he picked up at Autozone. He started it by puffing some starting fluid while cranking.

I am trying to get the glow plug circuit back together. I was planning on just wiring the circuit through a push button directly to 12V, but the whole indicator thing threw me and made me think it had more purpose than just giving feedback that the circuit was working. So I guess my question is if I can simply wire the plugs directly through a push button or do I need to find a new indicator (parts for this beast are nearly impossible to find)

 

[Fuddy1952]

Maybe call NKG who can tell you how long they can/should be on. I'm thinking your best bet would be to wire in that device DL posted, it looks like a high current glow plug light assembly made for them.
NKG can also tell you current draw.
A Ford site (V8 truck) said "all 8 draw about*190 amps, so figure each one would draw almost*25 amps."
So a 4 cylinder would be about 100 amps, so you would need a hefty switch and wire, although they're not on long.

 

[radios1]

it seems to me that the previous owner was whacked, maybe from a head injury, or drug use. you don't go and remove all the electrical wiring from a device, unless you are scrapping it!!.. every bit of that wiring served a valid purpose, and it will be very hard for a non Engineer to restore that wiring, unless the full wiring harness with all the switches and gauges are purchased. yes, the indicator needs to be wired in, but, you also need the relay for that amount of current, 100 amps total?. then you still need to worry about engine RPM, and oil pressure.. it's a real mess you have!..