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Discussion Starter · #1 ·
I wasn't sure whether to continue this post or start fresh so I'm starting fresh.
I just replaced the wiring harness and time delay module on a 318 (thanks antiqueetc). Before it wouldn't turn over, now it will. But I don't get an fire to the coil. When I first got the harness and module in, I pulled a plug and grounded it to the block with the plug wire on, tried it, I thought it fired, stopped the continued the re-assembly (gas tank, battery , etc). After getting everything else hooked up, I tried it again. Now I'm not getting any spart. I pulled the breather assembly off to check the points and the wire from the coil had a lot of insulation gone and may have been shorting out. But I checked for volatge in to the coil and have nothing. I can rig a wire from the ignition switch to the coil, or even jump it to the battery to see if the coil is ok, but what will casue it to get no electricity from the module? Or the wiring harness anyway. I checked both inline fuses and they look ok. The 3 amp I checked with a meter and it seems good, the other looks ok. What is my next step.

Thanks to everyone who looks and to anyone who has any advice.
 

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The Magnificent
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Remove the other wires from the positive side of the coil, then you may hook a wire directly from the battery.

I think you may have some poor ground connections yet. The TDM is bolted down and the grounds from it are tightly secured?
 

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Discussion Starter · #3 ·
Yes to the grounds and being bolted down correctly.
If I trip any of the safeties (seat switch, pto, neutral) it doesn't turn over.
One thing I did notice and didn't take much note of is that the oil light never came on.
I don't think it ever came on with the old module and harness either.
Is there anything besides the module that interrupts the voltage to the coil?
 

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I color outside the lines
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If I remember there are two types of 318s. Points and later electronics. So you are sure yours is points?

The circuits are about the same except the electronic part replaces the points.

The coil needs two things to function. Positive which comes from the circuit board with time delay module and the on/off ground from the points or electronic module.

The points wire shorting out shoudlnt have hurt anything.

So turn the key on and check 12 volts at the coil. If you dont have it then you need to work backwards.
 

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Discussion Starter · #5 ·
If I remember there are two types of 318s. Points and later electronics. So you are sure yours is points?

The circuits are about the same except the electronic part replaces the points.

The coil needs two things to function. Positive which comes from the circuit board with time delay module and the on/off ground from the points or electronic module.

The points wire shorting out shoudlnt have hurt anything.

So turn the key on and check 12 volts at the coil. If you dont have it then you need to work backwards.
I've seen the points with my own eyes.
And I have no fire to the coil.
The next thing I see on the wiring diagram is the time delay box. Simple electrical circuits I can do, electronics no.
The only thing betwen the module and the coil, is wire & 2 connectors.

John Deere says there is no way to test the time delay box.
 

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Discussion Starter · #6 ·
Can anyone tell me if the oil pressure switch cuts the power? That sounds like something that might happen.
Is there any way to test the switch?
 

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oki the 318 only has three wires to the motor besides starter and one is for the oil sender. You could test the sender by either unplugging it or jumping it across. I doubt thats it though because engines dont have oil pressure when they are not running and you need spark to start it.

When you say no fire to the coil, do you mean there is no 12volts or the coil is not firing (on the high voltage side)

Its a pretty simple circuit really although the time delay module confuses things.

Do you have a volt meter?

I would run a wire from + of battery to + side of coil and crank it over and see if it starts. If not then its motor related.
 

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Discussion Starter · #8 · (Edited)
No 12 volts to coil.

On another forum, I read that some think the seat safety switch is an always open switch (close it by raising off the seat and it grounds the system). Is that correct?

The wiring diagram I have does show an open switch on the seat.

I have a lot of stuff I have to take care of today, so I might not make it back to the tractor for a few days.

Is there anyplace that tests the modules or anyway to test the module?
 

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For testing purposes Take a sissors Cut a little strip out of an aluminum beer can {after you have drank the beer }It will be about 1/4 x 1 1/4 " bend it in a u shape Unplug the seat and plug it in.. Now remove the wires from the coil. Neg. {points] Pos {Battery} Now Take the wire offa plug Insert a NEW plug in the wire Ground it to the engine. Put a jumper from the battery Posative to the pos. coil. hook the condensorto the Neg side. Now you are set. Just a quick ground and the coil will fire if it don't the coil may be the problem; If it fires I would check the ignition switch. The Onan is one of the more simple streight forword engines. A lot of problems come from missunderstandingthe problem. Good luck.. Life is good. We can solve and problem if we know what it is.
 

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Can anyone tell me if the oil pressure switch cuts the power? That sounds like something that might happen.
Is there any way to test the switch?
I don't see the oil pressure switch in the starting circuit diagram anywhere so it must not cut power. Likely just controls when the oil pressure lamp is lit!
 

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I color outside the lines
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I don't see the oil pressure switch in the starting circuit diagram anywhere so it must not cut power. Likely just controls when the oil pressure lamp is lit!
I agree. I just downloaded a schematic and looked and the oil pressure sender is just for a lamp.

I also noticed the starter circuit has nothing to do with the module like it does on some tractors.

Will the 318 crank and start without the PTO engaged without you being on the seat?

Appears all the PTO switches tie into the module as well.
 

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Discussion Starter · #12 ·
I agree. I just downloaded a schematic and looked and the oil pressure sender is just for a lamp.

I also noticed the starter circuit has nothing to do with the module like it does on some tractors.

Will the 318 crank and start without the PTO engaged without you being on the seat?

Appears all the PTO switches tie into the module as well.
The tractor cranks very well, just does not put any voltage to the positive side of the coil.
When you flip the pto switch, it doesn't try to crank, I expect that.

I haven't tested the coil yet. But the ignition switch is brand new. I just bought it Thursday.
 

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Discussion Starter · #13 ·
For testing purposes Take a sissors Cut a little strip out of an aluminum beer can {after you have drank the beer }It will be about 1/4 x 1 1/4 " bend it in a u shape Unplug the seat and plug it in.. Now remove the wires from the coil. Neg. {points] Pos {Battery} Now Take the wire offa plug Insert a NEW plug in the wire Ground it to the engine. Put a jumper from the battery Posative to the pos. coil. hook the condensorto the Neg side. Now you are set. Just a quick ground and the coil will fire if it don't the coil may be the problem; If it fires I would check the ignition switch. The Onan is one of the more simple streight forword engines. A lot of problems come from missunderstandingthe problem. Good luck.. Life is good. We can solve and problem if we know what it is.
The coil tested fine.
 

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Okietool, there is no specific TDC test. From what I can tell you nearly have to do every electrical test to test the wires leading into the TDC so that you can see if they have the correct voltages. I would think that the JD dealer would have a simple plug-in TDC tester of some sort! I could be wrong though as I've never asked. Hope someone else has a better answer for you!
 

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I color outside the lines
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I would try to troubleshoot it in this manner.

Red arrows show power (+) going in and out of module.

Appears the ignition solenoid should be powered all the time from the 20 amp fuse. All safety conditions need to be met which grounds the ignition relay at the green arrow.

I dont know much about the 318s. What is the discharge control/light? Is that for deck PTO?



 

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Discussion Starter · #18 ·
Well kiss my grits. Working backwards, I think the 8 wire connector may not have been making contact. I pulled it apart and it was kind of dirty so I brushed and blew evrything out then sprayed it with good ole WD40. Plugged it back in, hooked it up to a charger/booster and now I have 12 volts at the coil. Then it was supper time. Yup, haste makes waste. To be continued......
 

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Don't keep us in suspense!!!:Stop::Stop::Stop:

What happened???
 
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