ceramic resistor

I just bought one of the little ceramic resistor that fits on the hotwire going to the coil. I have fire going to it with the key on but none on the other end coming out, hence the tractor won't crank.(Ford 700). The tab on one end seems to be loose. The coil of wire inside it is not broken. Any ideas about it?

If an ignition ballast resistor (between IGN output of ign switch and coils input) were open (infinity ohms), then there wouldnt be any voltage on its output even if 12 was present on its input as should be.

The ballast resistor should measure continuty from end to end of around 1.25 to 2 or so ohms.

If theres battery voltage on the resistors input (from IGN output on Ign switch) and the output is connected to the LV Primary of a coil and the coils other terminal is wired to the distributor and the points were closed and good and working, Id expect 12 volts on the resistors input but only 6 on its output i.e. a 6 volt voltage drop ACROSS IT. ASSUMING A 12 VOLT TRACTOR WITH 6 VOLT COIL AND A BALLAST AND ALLS CORRECT AND WORKING AND POINTS CLOSED

If the points were open Id expect 12 volts on the resistors input and likewise 12 on its output.

TAKE AN OHM METER AND MEASURE THE RESISTORS RESISTANCE!! It cant be an open circuit but should be around 1.2 to under 2 ohms or so typical.

If for some reason (wiring wrong or a short etc) the output of the ballast was connected to the tractors frame ground, Id expect 12 on its input but zero on the output i.e. its dropping the entire 12 volts across it

If its a regular series ignition circuit ballast resistor (between ign switch and coil) and bad/open that can prevent a spark but shouldnt stop starter motor from cranking????????????

Sure its an ignition balalst and sure all is wired correct???

MEASURE ITS CONTINUITY AND RESISTANCE

John T

(quoted from post at 14:41:43 08/07/12) I just bought one of the little ceramic resistor that fits on the hotwire going to the coil. I have fire going to it with the key on but none on the other end coming out, [b:7b800cb1a4]hence the tractor won't crank.(Ford 700)[/b:7b800cb1a4]. The tab on one end seems to be loose. The coil of wire inside it is not broken. Any ideas about it?

Click to expand...

???? The resistor should not be in the cranking circuit!

bump your starter!!!!! points closed will pull the voltage to near zero,thats the purpose of the resistor,and why its a high wattage one, to shed excess heat away from the coil. if you get no voltage anytime, you either have a short to ground on your ignition wiring , coil, in dist, or your points are not opening. At least theoreticaly, you should see your points opening and closing on your amp guage while cranking if everthing is working correctly.

mb58,

Just to add one small thing to what John T said, it would also be good to disconnect one of the wires that is going to the resistor when you check the resistance with your ohm meter.

By doing so, you'll insure that you're not getting a false reading from a parallel circuit that could be around the resistor.

Good luck,

Tom in TN

What ???
You stick to lawyering and I will stick to basic electricity John
Walt

The resistor has nothing to do with "cranking" or do you mean "run" or "fire"?

Pretty hard to help troubleshoot with only partial information.

Why did you buy the resistor in the first place? Are you modifying your rig?

What kind of tractor?

Did it crank before? Is it a solenoid control to the starter and you may have accidentally broken the connection to the solenoid? Connecting a resistor in the hot wire to the coil will not prevent it from cranking all else being correct.

When you say "cranking" do you mean actually starting or just not spinning the engine over?

Adding to John T's input, he said:

"If for some reason (wiring wrong or a short etc) the output of the ballast was connected to the tractors frame ground, Id expect 12 on its input but zero on the output i.e. its dropping the entire 12 volts across it"

Could happen, and if it were I would expect the resistor to be very warm in a short period of time.

He also mentioned an open resistor and open points, in which case I would expect the resistor to be cold/ambient temperature.

Good luck!

No problem Walt, buttttttttttt besides a Lawyer, (JD, Doctor of Jurisprudence Indiana University 1994) Ive been an Electrical Engineer forty two years (BSEE, Purdue University 1970) and I was a Secondary Power Distribution Design Engineer much of my life. In addition to all that, I farmed for years and was a used tractor and farm machinery dealer who pretty much did all his own repairs (school of hard knocks lol)

Sooooo I enjoy and am glad to help the good folks here with BOTH electrical and legal questions.

I really enjoyed the pictures of you and the dog and the kids, keep posting and helping us anytime you can...

God Bless ya Walt

John T in Indiana

What I was saying John is don't talk like a lawyer when describing a simple ignition system. Battery to ballast resister to coil plus side from coil minus side to points and back to ground.
Points open coil side of resister near battery voltage points closed 6 to 8 volts engine running 300 as the points open. That's what the capacitor is for to take up the extra voltage and bleed off to ground. When the points open there is a collapse of the magnetic field in the coil which gives you 20,000 at the plugs and 300 at the points. Close points to build the magnetic field back up. As I said simple electrical circuit.
Walt
You got to watch using to much complicated info when talking to old farmers who have trouble getting the battery hooked up correctly. Not to that all of us are that way but a few have been asking question to this matter.
OH! 50 years as a machinest and auto/ heavy equipment mechanic. Including courses in basic auto electric not electronics like the new cars have bummer.

Walt, I apologize if the way I talk (as an engineer or lawyer, Hey, thats me and I'm proud of my accomplishments and hard work) offends you or if anything I said offends you, feel free to read or not read my comments and feel free to use your own methods to help, the more the merrier, thanks for your input and help, I and I'm sure others appreciate what you do.

Its my intention to HELP folks here NOT fight or argue and remain polite and professional. However, for years here I have helped people here and they have been greatful and thanked me and I plan to continue to help them the best I can (even if not everyone likes it), I have received numerous thank you e mails from the good folks here who appreciated the way I explained things and was well received and thanked (and paid money even) when I gave tractor electrical seminars at major shows all over the country and wrote tractor electrical articles for major magazines.

So, while you may not approve of my teaching methods (and thats sure your right) most others have, to each their own, not a problem, if we all liked things the same what a boring world lol.

While there are technical some errors in what you say above, I wont argue and feel each are entitled to their own opinions, right or wrong. If there were errors in my post Id enjoy and appreciate a technical explanation of what it is I said that wasnt correct???? hey NO ONE here is perfect (YOURS TRULY SURE INCLUDED) and if anything I said was incorrect, an explanation of how it is wrong is certainly appreciated so we can all learn something, were never too old to learn I figure

So best wishes and God Bless you and Im sure the gents look forward to your help, but I also like to help in my own way (and how I talk as an engineer) and plan to continue to do so same as I have on here for years and years.

Take care now Walt, I look forward to your help on these boards

Ol John T in Indiana

Fer sure, if there was some sort of short in the wiring (it happens) and the output end of the ballast were dead shorted to frame ground NO VOLTAGE FROM THERE TO GROUND........and no spark of course, Im unsure what he means by she wont crank however???? as the ignition circuit shouldnt have anything to do with the cranking nor any ballast in the start activation circuit??????????

Fun chat even if we cant help him

John T

Yeppers, ON THE POINTS if they are closed and working well that should be a short to ground so theres no voltage there with respect to ground. Of course, however, up on the output of the ballast (input side of coil) if all is wired correct and working and no improper shorts, there would be around 6 volts with respect to ground when points are closed and 12 if they were open.

Fun chat, hope he gets it figured out

John T

Not to argue or complain John but where are The technical problems in my layout of how the spark system on a simple tractor works.
Walt
Try this page