IH 574 no power at coil

[DickIllyes]

Tractor was running normally mowing with bush hog when died. Believing out of gas filled up but would not start. Previous unpredictable starter engaging led to replacement of starter switch, and old switch was bad, high resistance/open when turned to start position.

Now no spark and no power at input to coil, and no apparent connection to coil input from wire connected to ignition position of starter/ignition switch. Seems impossible to trace wire in harness since it looks like all are red. Almost has to be same wire that was on old switch, and switch ohms out normally. There must be some component on that line somewhere making it open but I am stumped. Any suggestions appreciated. Harnesses buried behind lots of steel.

 

[RBoots]

I don't know about your 574, but out 674
has a ballast resistor mounted up high
above the coil, under the hood. It has
burned out before.

 

[Janicholson]

The wire itself could be a resistor wire. They do fail as they have less flexibility and are moderately delicate. It might depend on whether yours has Lucas, or Delco ignition. If you replace the wire, make sure to use a separate resistor (66 chevy is a good choice) Jim

 

[old]

I do not know that tractor as such but if it was mine I would try a hot wire from the battery ignition side to the ignition side of the coil and see if it would run. If it does then the problem is from the coil back to the battery if it still does not run it is in the distributor

 

[mattofvinings]

You could get a piece of wire and temporarily run (externally to the harness) from the "ignition on/run" maintained position of the switch to the coil. Dont bypass the ign resistor if present. That should prove out any issues in the wiring harness.

Also I would use voltmeter to make sure there is 12vdc at the rear terminal, to chassis ground, when the switch is turned from "off" to "ignition on/run"

 

[John T]

Sure, you can "hot wire" direct to the coil to make it run, but if there's any sort of a ballast resistance unit, (may be burned out and open) be it a resistive wire link or a discrete resistor, between the switches IGN output and down to the coil, THAT NEEDS TO BE REPLACED otherwise you risk overheating the coil and prematurely burning the points if its like a 6 volt rated unit on a 12 volt tractor. In the alternative, if the coil is a 6 volt (around 1.2 to 1.8 or so ohms), you can re wire the system by running a new wire from the ignitions switches IGN output, add in series a voltage dropping (12 down to 6) external bathtub style ballast resistor which approximately matches the coils resistance (be it 1.2 to 1.8 etc ohms) to achieve a 50 50 voltage divider dropping 6 across the ballast leaving 6 for a 6 volt coil. Of course, if you use a 12 volt full rated coil no ballast required, simply run a new wire down to the coil from IGN switch.

NOTE I'm talkin typical old tractor 6 volt (around 1.5 ohms) or typical old tractor full 12 volt rated (around 3 ohms) coils here NOT old car coils which may or may not require a slightly different ohms rating for the coil and matching ballast. To drop 6 volts and leave 6, 50 50 voltage divider, the ballast and coil resistance need to be the same.

John T

 

[DickIllyes]

(quoted from post at 06:06:34 09/24/17) Sure, you can "hot wire" direct to the coil to make it run, but if there's any sort of a ballast resistance unit, (may be burned out and open) be it a resistive wire link or a discrete resistor, between the switches IGN output and down to the coil, THAT NEEDS TO BE REPLACED otherwise you risk overheating the coil and prematurely burning the points if its like a 6 volt rated unit on a 12 volt tractor. In the alternative, if the coil is a 6 volt (around 1.2 to 1.8 or so ohms), you can re wire the system by running a new wire from the ignitions switches IGN output, add in series a voltage dropping (12 down to 6) external bathtub style ballast resistor which approximately matches the coils resistance (be it 1.2 to 1.8 etc ohms) to achieve a 50 50 voltage divider dropping 6 across the ballast leaving 6 for a 6 volt coil. Of course, if you use a 12 volt full rated coil no ballast required, simply run a new wire down to the coil from IGN switch.

NOTE I'm talkin typical old tractor 6 volt (around 1.5 ohms) or typical old tractor full 12 volt rated (around 3 ohms) coils here NOT old car coils which may or may not require a slightly different ohms rating for the coil and matching ballast. To drop 6 volts and leave 6, 50 50 voltage divider, the ballast and coil resistance need to be the same.

Thanks John T I had never known how to determine the coil and ballast values. This should let me get it running.

John T

 

[rvirgil_KS]

My brother has a 574 gas that would not engage starter. We found the problem to be a connection in a big 8 pin plug located under the hood in front of steering wheel.

Ignition power also goes through that plug. My diagram shows light green wire from switch to plug, light green wire out of plug that then joins a white with orange and purple tracers that joins with a white wire from small terminal on start solenoid and goes to ignition coil. Any of those connections could be your problem. White with orange and purple tracer may be the resistance wire.

 

[DickIllyes]

(quoted from post at 07:58:45 09/24/17) My brother has a 574 gas that would not engage starter. We found the problem to be a connection in a big 8 pin plug located under the hood in front of steering wheel.

Ignition power also goes through that plug. My diagram shows light green wire from switch to plug, light green wire out of plug that then joins a white with orange and purple tracers that joins with a white wire from small terminal on start solenoid and goes to ignition coil. Any of those connections could be your problem. White with orange and purple tracer may be the resistance wire.

More good advice, thanks.