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Discussion Starter #1
As many know I had the center of my 318 taken apart enough to change the fuel lines from the tank to the carb. I found one wire in one of the connects was loose so I pushed it in until it was solid with tension against pulling back out (I know that much about connectors). I looked for any more issues I may have cause and saw none so I put the battery tray in and finished the assembly to go for a test ride. But before i left I decided to use compressed air to blow out the inner frame rails and around the front of the engine and whatever I could get under the engine tins. Then I went for a ride. At some point the battery light came on. :danger:

I made a copy of the electrical schematic and although I can read them I don't always fully understand why some things are the way they are.

My tractor has all safeties disabled (jumpered), per my wishes. I did those years ago. (I'm one of those weirdo's that believes safety is a personal responsibility -as much as humanly possible anyway-, not a companies, or something to be mandated by the government).

Anyway, all that aside... under the fender pan I found the rear lights common ground and placed it where the pan bolt would hold it, (I don't think that's the issue), other than that I can't see what I moved that might cause the battery light to come on.

Any ideas? Never had a problem before...everything has always worked, including the rear lights.
 

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If it is a single wire connector more than likely it is either

  • the wire from pto switch to the front pto. My 83 318 had the connector in front of the oil filter between engine and right side frame.
    Mine is full of greasy gunk. Will clean it out with brake cleaner and compressed air. Connector can be released with a small electrical screwdriver press in above the connector spade.
    (Spade releases from larger end of connector ... screwdriver goes in opposite the bump on the connector and above the wire.
  • Lights use similar single connector but is located above and forward of engine in hood. Follow headlight wire back and you will find it.
Neither of these however should cause dash light to illuminate. However with safety switches bypassed anything can happen. I recommend they be reconnected.

Photos would really help us. Can you give us a photo of the connector you had issues with.
 

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Randy,

Like Gabby, I also recommend that the safety interlocks be restored to factory condition...and it will help us verify that no other unintended hacks to the harness have crept into the equation. I don't like overzealous lawyer intrusion to machine design as much as the next fellow -- but at the same time I am not inclined to try to hack around the safeties on any of my firearms either.

If you can, try to measure the voltage at the battery at idle and at full governed speed...just to verify the health of your charging system. The charge indication lamp is driven by a function inside the TDCM, so a poor ground at that module can cause the sorts of symptoms you describe.

Here is the theory of how the charge indication on the 318 works -- note that it is a voltage level indicator and not a measure of current:
charging circuit operation.jpg

I highlighted the relevant section in this excerpt --
charge light for Onan engines.jpg

Chuck
 

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Discussion Starter #4 (Edited)
Thanks guys! I think that maybe both these things may have happened. I may have blown oily grunge into someplace it wasn't supposed to be. I also may have run the battery down. Easiest first is charge the battery. Then work from there. I was only running the engine at about 1/3 throttle on my jaunt around the field.

As for the safeties. Never! They haven't caused an issue in five years, it would be too coincidental for them to cause any issues now.

Chuck, I bypassed the safeties on one of my pistols but it's my test gun for working up odd 9mm loads. I rarely shoot it however. I have too many others I like shooting more, and they are too pricey for me to change them too drastically.
 

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Some of the more common issues I have found or read about are connections to the self resetting circuit breaker, starter switch, (I had a new OEM with a loose terminal) connections the the voltage regulator. Besides the wire going to the TDCM I think that is about all in that particular circuit. A service manual can tell you how to check the VR. I can never remember but the ac is checked on two outside connectors but what I cannot remember is do you measure this unplugged or connected. I do know you want to measure this at WOT with meter set to AC. DC volts come from center lug and plugged in it should read battery voltage plus what is coming from the VR, in other words at least 13.7VDC WOT.
 

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Thanks guys! I think that maybe both these things may have happened. I may have blown oily grunge into someplace it wasn't supposed to be. I also may have run the battery down. Easiest first is charge the battery. Then work from there. I was only running the engine at about 1/3 throttle on my jaunt around the field.

As for the safeties. Never! They haven't caused an issue in five years, it would be too coincidental for them to cause any issues now.

Chuck, I bypassed the safeties on one of my pistols but it's my test gun for working up odd 9mm loads. I rarely shoot it however. I have too many others I like shooting more, and they are too pricey for me to change them too drastically.
Your specified alternator output is usually at wide open throttle - mowing at 1/3 throttle would most likely drain your battery little by little because of the load from the clutch.

What you do with safeties in the privacy of your own home is up to you. Although they don't have much to do with your charging circuit, I would check the jumper continuity every so often - corrosion and vibration have an impact on anything moveable and with good jumpers, you have in fact removed doubt whether the switches work or not.
 

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Randy,

Since your 318 is air cooled, it is important to run it at full governed speed when under load. I think your post above about your "jaunt" was not under any load other than moving the machine under its own power, so that is not nearly as critical to engine speed. I am sure CaptPete is thinking of this information from the operator's manual in his post directly above when speaking of wide open throttle...

318 throttle recommendations from Deere.JPG

Chuck
 

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The air-cooled Onans and Kohlers in our GTs should be run at Fast Idle/WOT when working, mowing/tilling/etc., so the engine can cool itself. If everything is good with air flow on your 318, run the throttle up, tractor in N, and stand in front of the grille. You won't stay there for long because of the hot air exhaust. Down here in hot, humid NE Tejas I run my 212 with the right side panel off to keep the manual PTO cool in the summer months. It simply gets too hot with that panel on and the PTO get finicky about disengaging...even if it's been serviced to the T lately. From about November through May I can run it with the right side panel on if I want...but off it comes for the summer months.
 

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I'm going to agree and second a couple of above posts.

Air cooled engines should be at high RPM if they're working at all. The crankshaft essentially is the fan. They don't want to work with no fan.

The charging system is also dependent on crankshaft RPM. At one third off of idle, the charging system is not able to make even a fraction of it's rated output. With the PTO turned on, that probably dragged the stabilized voltage down WELL below the set point for the charging light driver.

Charge the battery, let it rest overnight, and take the tractor for another test burn with the engine speed up, and if you still have an issue, diagnose it from there.
 

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Discussion Starter #10
I'm going to agree and second a couple of above posts.

Air cooled engines should be at high RPM if they're working at all. The crankshaft essentially is the fan. They don't want to work with no fan.

The charging system is also dependent on crankshaft RPM. At one third off of idle, the charging system is not able to make even a fraction of it's rated output. With the PTO turned on, that probably dragged the stabilized voltage down WELL below the set point for the charging light driver.

Charge the battery, let it rest overnight, and take the tractor for another test burn with the engine speed up, and if you still have an issue, diagnose it from there.
That sounds like the plan. I had the charger on the battery today since it was only at 80%. I just turned the charger to 'recondition' and will leave that on for as long as it takes or until I get outside tomorrow. I still have to sharpen the blades and put the deck back on anyway, if it's not healthy after at least 12 hours then I need a new battery I guess. It was at a full 100% charge when I switched 'recondition' on though. But a prolonged low amp soak shouldn't hurt it.

I haven't had any electrical issues at all until I took everything apart, that's why I hate taking this stuff apart if it ain't broke.
 

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Discussion Starter #11 (Edited)
Well, I got around to the fuel tank finish up task and I also checked charge voltage at battery. Alternator is doing it's thing at about 14.5volts at battery at full throttle and about 13.6 volts at idle. At rest battery voltage was 12.7v.

The battery may have been at bit low because earlier today I ran it out of gas and forgot to go out and turn the switch off for about an hour, then I spun it for about 20 seconds to be sure that it actually ran out of gas instead of for some other reason. It was out of gas at the primary pickup.

Put in the reserve pickup and pressed on the tank in reserve position to help fuel into the filter and it fired right up. Then I checked voltages.

The light is still on. I guess next is dig back down inside under the battery and check fuses? At least the 2 amp fuse (F2)?

Am I close?
 

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Yes.
Post #3 from Chuck says fuse f2.
It may just be some corrosion on it.
 
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Discussion Starter #13
OK, I checked both fuses...both OK, no corrosion and looked fine. I have yet to make sure I don't have any broken wires in the pink and red wires but it's looking more and more like it's the TDCM (I guess it could be in the ignition switch also), or maybe (and most likely) a bad connection at the multi wire connector. I did find a loose connection in that connector and I pushed it back into the connector with a small screwdriver....coincidence? Maybe. But, I'm now thinking that it was loose for a reason. The guy I bought this from was not what I would call honorable. Even if he did say he managed a coop in his small town and lived in a very nice house. I have found a number of things that he said about it that simply were not true.

Regardless, that was then, this is now. I can't actually get my hands down into the area where the connector is. It was a struggle to push that connector back in and it's highly possible that it did not stay. I'll check that tomorrow and since I never did get around to sharpening the blades on the deck I still have that to do.
 

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I did a little looking in the manuel for ya.
Screenshot_20200628-221846_Drive.jpg

Check for batt voltage at pin #5 in the x23 connector.
That's voltage in to tdcm.
If that checks ok, then....
Run tractor,
Check for a ground signal at pin 1 of x23 connector.

If you have the proper voltage at pin 5 going to tdcm,
And the ground on pin 1 when running....
Tdcm is probably bad.
But you'll want to be sure the wire in pin 1 isnt finding ground somewhere else.

Pin 2, right next to it is the ground wire.

Hope I helped. Good luck.
 

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Skwirl,

Just a few things about your post above:

Yes, X23 pin 1 is the wire that controls the dash lamp for charge condition -- +12 volts is lamp not lighted and low (dear zero volts) is lamp lit.

However, pin 5 is the sense voltage for the voltage detection circuit inside the TDCM (pin 3 actually provides power to the circuitry inside...)

X23 pin 2 is not a ground connection -- it is actively driven by a relay inside the TDCM and provides power to the ignition and the hour meter.

X22 pin 10 on the TDCM is module ground, and a poor connection here is often the cause for many odd behaviors falsely blamed on the TDCM itself. A bad module ground is very likely the root symptom in this case, but not the only possibility. It is best to eliminate all external potential causes of your symptoms before investing a large amount in a new TDCM which is not a returnable purchase at Deere. I never recommend buying a used TDCM because they can be damaged by harness hacks by uninformed owners and are therefore an unknown quantity -- exchanging such an unknown into your present symptoms still leaves considerable ambiguity.

Here is a document on what each pin of the TDCM does and what voltages/conditions are normal for a working one for your testing purposes...

View attachment TDCM connector voltage measurements and their meanings.pdf

Chuck
 

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Discussion Starter #17
Thanks all! I think I have it figured out. I just have go out and see it personally down inside the rat's nest of wires and figure out how I'm going to access all those points in order to check them. It's not as bad as that but like I keep saying, with everything packed into that space access is limited from the top.

I don't want to admit I'm a weather wimp but the humidity today is near 85% and the temps (for me) are a bit too high to make working looking down on electrical stuff (connections) that would be sensitive to salty sweat pouring down into it out of the question. I went outside with the dogs earlier and it felt horrible out there. I have to work under the sky, no shade (although it is cloudy today) I could still feel the sun.

I'm really considering going to Home Depot or someplace and buying a pop-up canopy for some shade. I'm getting soft in my old age! :cry:
 

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I'm getting soft in my old age!.
Sometimes that can also cause you to get smart. Shade is always better whether it is a popup or a big shade tree.
 

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Thanks all! I think I have it figured out. I just have go out and see it personally down inside the rat's nest of wires and figure out how I'm going to access all those points in order to check them. It's not as bad as that but like I keep saying, with everything packed into that space access is limited from the top.

I don't want to admit I'm a weather wimp but the humidity today is near 85% and the temps (for me) are a bit too high to make working looking down on electrical stuff (connections) that would be sensitive to salty sweat pouring down into it out of the question. I went outside with the dogs earlier and it felt horrible out there. I have to work under the sky, no shade (although it is cloudy today) I could still feel the sun.

I'm really considering going to Home Depot or someplace and buying a pop-up canopy for some shade. I'm getting soft in my old age! :cry:
It's kind of brutal out there today, I don't blame you. My son picked up a canopy tent (think farmers market) at Walmart for ~$40.

Fine for shade and light rain.

I just replaced my furnace and kept the old fan, which I converted into a floor fan for the garage & outdoors. It moves some air and will make a shaded area tolerable on a day like today. Any extra air movement helps in this humidity.
 
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