C-120 no spark

[huey 7]

I have a c-120 that was running and suddenly stopped! looking into it further it doesn't have any spark i checked the positive side of the coil and there is no power getting to the coil with the key in the on position. When i try and start the tractor it turns over fine but while cranking the engine there is still no  power to the + side of the coil so i decided to check the ignition switch for continuity and is working properly. After all this i decided to run a jumper wire to run power to the coil and started fine and drove it to the shed and that is where it sits until i figure it out, any suggestions on how to trouble shoot more?

[gwest_ca-(File Mod) 10,488]

What is the model number of the tractor? Good to look at a wiring diagram to see what safety switches are involved.

On some the ignition is controlled by 1/2 of the pto switch and the seat switch.

Pto OFF the pto switch powers the ignition.

Pto ON the ignition circuit is switched to the seat switch which powers the ignition.

The thinking behind it is with the pto ON and mower deck running operator falls out of seat the engine stops.

 

Garry

[huey 7]

2 hours ago, gwest_ca said:

What is the model number of the tractor? Good to look at a wiring diagram to see what safety switches are involved.

On some the ignition is controlled by 1/2 of the pto switch and the seat switch.

Pto OFF the pto switch powers the ignition.

Pto ON the ignition circuit is switched to the seat switch which powers the ignition.

The thinking behind it is with the pto ON and mower deck running operator falls out of seat the engine stops.

 

Garry

1976 c-120 is the year unsure of model number but did look it up a few years ago and the pto safety switch and the seat switch have been bypassed the only one that hasn't been bypassed is the clutch pedal safety.

 

Edited September 3, 2019 by huey

[ebinmaine 62,980]

Huey it seems you're already headed the right direction and just need to narrow your testing a little.

If you know can drive the tractor by jumping the actual chassis wire try only jumping from

 

ignition switch to clutch safety switch

 

 clutch safety switch to coil

 

around clutch safety switch

 

One of those 3 tests may show you right where the issue is.

 

There shouldn't be a seat switch on that tractor.

 

 

[gwest_ca-(File Mod) 10,488]

Clutch pedal switch controls the starter circuit.

All you can do is follow the ignition (I) circuit from the ignition switch to the coil. Check all the bypass connections.

 

Garry

[The Tuul Crib 7,332]

to

 

[oldredrider 2,547]

Check your ammeter connections. If it died suddenly, first place to look.

[953 nut 51,541]

9 hours ago, huey said:

i decided to check the ignition switch for continuity and is working properly.

Check any connections along the wire from the switch to the coil to see if they are corroded or need to be tightened. It could be the switch is not able to cry enough current to the coil. If the spring contacts in the switch are weak they will look good with a meter but fail under load.

[huey 7]

14 hours ago, 953 nut said:

Check any connections along the wire from the switch to the coil to see if they are corroded or need to be tightened. It could be the switch is not able to cry enough current to the coil. If the spring contacts in the switch are weak they will look good with a meter but fail under load.

I think you are right 953 Nut i checked the ignition switch for continuity and was fine, but when i checked the Ignition wire from the switch to the coil i was getting continuity through the wire so pretty sure even though the switch tested fine it can't carry enough current to the coil!