Hi all ... I've got a 1983 420 w/B48G (sn: M00420X222808)and a loader on the front. Bought last year, used a little bit, and always seemed fine. But now my battery light stays on and the engine dies when I flip the PTO switch. The rear end wiring is "balled up" under the battery tray and the seat switch is jumpered up ... there are no fuses that I can find. Suggestions? Thanks, Bryan.
Another 420 PTO Clutch Issue ...
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Bryan,
My best guess is that you have a short in the seat safety circuit(giving you the battery light) and it is showing you off the seat which kills the engine when the pto is engaged-per the safety circuit function. I'd pull the fender pan and look for a wire that has contacted the metal pan or frame. Your jumped seat connection might actually be making contact. Make sure it's insulated. Good luck. Post back with more info as you run tests and eliminate causes.
Mike
My best guess is that you have a short in the seat safety circuit(giving you the battery light) and it is showing you off the seat which kills the engine when the pto is engaged-per the safety circuit function. I'd pull the fender pan and look for a wire that has contacted the metal pan or frame. Your jumped seat connection might actually be making contact. Make sure it's insulated. Good luck. Post back with more info as you run tests and eliminate causes.
Mike
Mike ... thanks for the feedback. I pulled the rear/seat wiring from underneath the battery tray ... found a small place where the sheathing is worn away, but the pink wire inside looks intact and not exposed. I tried another switch ... no difference. I circled 2 red wires that are connected together in one pic ... not sure what these are for. Outside of some wiring for an electric fuel pump, most wires look clean & normal. I'll try another switch tomorrow as the one I tried I've never used before. Starts & runs fine, but acts just like you described ... PTO kills engine as if I was not sittin' on a good seat switch. Thanks, Bryan.
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Bryan,
Just realized my mistake. If the seat switch would have been shorted, then the tractor also would have died when the hydrostatic control lever was moved off of neutral.
Did you check your fuse block? I'm guessing its the 10A fuse.
It seems like I've come across this before. Chuck Van Dusen is the one that know this item VERY well. You might send him a message and ask him if it turns out the fuse block isn't the problem.
Mike
Just realized my mistake. If the seat switch would have been shorted, then the tractor also would have died when the hydrostatic control lever was moved off of neutral.
Did you check your fuse block? I'm guessing its the 10A fuse.
It seems like I've come across this before. Chuck Van Dusen is the one that know this item VERY well. You might send him a message and ask him if it turns out the fuse block isn't the problem.
Mike
Mike ... I'll look again, but I didn't see any fuses before. Out of curiosity, I moved the hyd. control lever out of 'neutral' and it started right up! I need to compare what's what to another tractor, just haven't had time yet. The lights are wired 'on' all the time (don't know why) and an electric fuel pump is mounted on the firewall ... any idea what the 2 pink/red wires connected together in above picture are for? Thanks, Bryan.
Managed to spend some time on this recently. Made a couple discoveries upon closer inspection. First, I found that one of the connectors on the voltage regulator had broken off and the hot wire was taped alongside the spark plug wire ... both wires to the stator (does one go to the coil?) are intact. I replaced the regulator off of a parts tractor, but had never had running so I don't know anything as to its status. I put my multimeter to the battery and got 12.13v ... started tractor and now read 11.94v ... I believe I should be getting 14+, correct? If so, how can I test the regulator? If it's good, can I conclude that I've got a stator problem?
Secondly, I found that the neutral safety switch was situated too far 'in' to make good contact with the fwd/rev lever. I adjusted its position 'outward' and also noticed that the two purple wires had been jumpered together with a connector of some sort. I undid this to try to understand what was going on here. When I started the tractor, it would run terribly when moving the lever out of neutral. I replaced the neutral switch and now moving out of neutral completely kills the engine. Engaging the PTO also kills the engine. I'm back to thinking the seat switch is shorting out somehow. I can measure 11.55v where the seat switch wires are jumpered together, so would/could that still be my problem? The only other thing I've found is that a red and a pinkish wire are jumpered together (see 2nd pic above). Comparing this to another tractor, both run to a fuse and then to the ignition switch. My ignition switch does not have the connector to accept these wires. Help!
Dale ... thanks for the schematic, I just haven't been able to decipher yet ..
Thanks,
Bryan
Secondly, I found that the neutral safety switch was situated too far 'in' to make good contact with the fwd/rev lever. I adjusted its position 'outward' and also noticed that the two purple wires had been jumpered together with a connector of some sort. I undid this to try to understand what was going on here. When I started the tractor, it would run terribly when moving the lever out of neutral. I replaced the neutral switch and now moving out of neutral completely kills the engine. Engaging the PTO also kills the engine. I'm back to thinking the seat switch is shorting out somehow. I can measure 11.55v where the seat switch wires are jumpered together, so would/could that still be my problem? The only other thing I've found is that a red and a pinkish wire are jumpered together (see 2nd pic above). Comparing this to another tractor, both run to a fuse and then to the ignition switch. My ignition switch does not have the connector to accept these wires. Help!
Dale ... thanks for the schematic, I just haven't been able to decipher yet ..
Thanks,
Bryan
Tom ... When I started into this, the PTO wouldn't kick in so I checked the gap and seemed fine. Since then I've tried to straighten out the wiring issues and flipping the PTO switch or taking out of neutral kills the engine, so I'm ruling out gap issues for now.
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Brian,
If turning on the PTO kills the engine, then the TDCM is probably working just as it is supposed to and there is something wrong elsewhere in the safety interlock circuits. Does the engine also get killed when you move the ground speed lever out of the neutral slot? If so normally I would suspect the seat switch is not working as it should -- or likely there is an open or short in the wiring to the seat switch or the 3 amp fuse is blown (or the fuse holder is intermittent...)
Since your wiring is completely hacked, it will be difficult to remotely diagnose this issue...if you are patient you should try to restore the factory wiring in all respects -- using the wiring diagrams in the TM1590 manual.
Chuck
If turning on the PTO kills the engine, then the TDCM is probably working just as it is supposed to and there is something wrong elsewhere in the safety interlock circuits. Does the engine also get killed when you move the ground speed lever out of the neutral slot? If so normally I would suspect the seat switch is not working as it should -- or likely there is an open or short in the wiring to the seat switch or the 3 amp fuse is blown (or the fuse holder is intermittent...)
Since your wiring is completely hacked, it will be difficult to remotely diagnose this issue...if you are patient you should try to restore the factory wiring in all respects -- using the wiring diagrams in the TM1590 manual.
Chuck
Chuck ... yes, moving the ground speed lever out of neutral kills the engine. The seat switch has been jumpered over ... the wiring has been pulled up and wound up underneath the battery tray. There is a small area of the sheathing missing and exposing the wiring (see first pic above), but it looks clean & intact. I've cut the connector on the end and rewired to make sure it's connected. I measured 11+ volts at that end ... can I assume I've got continuity back to the tractor? I have no fuses ... the red & the pinkish wires that have fuses and run to the ignition switch on another tractor are jumpered over to one another on this one (see second pic above). I don't have the extra connector on my ignition switch to accept these. I'd like to restore to factory wiring ... right now I'd just like to get PTO functioning so I can lift the front bucket and move the tractor elsewhere. Thanks, Bryan.
Bryan, do you have TM1590? With a hacked harness, neither Chuck nor I can tell you where to look without having the tractor in front of us.
Your "battery light stays on" may be failure in the charging circuit. The DC output tab on the voltage regulator should be at battery voltage, and should come up about an additional volt or more when you start the tractor. Battery voltage should come up the same.
In an emergency situation, a 12 or 14 gauge wire with clip leads from the battery to the PTO
should make it engage.
Hank
Your "battery light stays on" may be failure in the charging circuit. The DC output tab on the voltage regulator should be at battery voltage, and should come up about an additional volt or more when you start the tractor. Battery voltage should come up the same.
In an emergency situation, a 12 or 14 gauge wire with clip leads from the battery to the PTO
should make it engage.
Hank
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Brian,
Here is what the wiring excerpt for the ignition interlock looks like from the TM1590:
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And here is the starting interlock excerpt:
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...we will have to look at them together as each shows only part of the picture on why the ignition is killed if you turn on a PTO or take the ground speed out of neutral. Note that in the second diagram there is 12 volts on the key switch terminal S2 (the #710 purple wire) even when the key is in the RUN position. The upper diagram also shows this #710 purple wire, but not why or when it is 'hot' with 12 volts.
In the upper drawing, relay contacts A must be closed to enable the ignition to make spark. IF the transistor C is conducting, as it will be when key switch S2 is hot supplying voltage to TDCM X23 pin 7 via the #705 purple wire, the engine will continue to run -- INDEPENDENT of the seat safety detect enabled at TDCM X22 pin 9. If the seat safety conditions are satisfied, that pin 9 also receives 12 volts, the one-second timeout in the TDCM is inhibited and transistor D also conducts. You must have either transistor C or transistor D conducting to keep the ignition enabled. If there is no 12 volts on connector X22 pin 9, then opening anything in the series circuit in the lower drawing will kill the engine. If your 420 is below S.N. 595881 then you do not have the parking brake switch, but turning on a PTO or moving out of Neutral will definitely remove voltage from key switch terminal S2 and therefore turn off transistor D.
Use a voltmeter to measure what voltage you have at TDCM X22 pin 9 when the key is in the RUN position -- if it is not 12 volts with the seat switch bypassed as you believe it is then there is an open in the wiring on the #800 or #810 pink wires, or a bad fuse at F2 (or an intermittent fuse holder if it is the older plastic tube style...)
Help me here with some feedback of what you actually find on your particular hacked wiring with your observations and voltage measurements and we can continue to troubleshoot if needed. Like Hank says, we can only tell you where to look first -- where to look next is dependent on what you find at each step...
Good luck...
Chuck
Here is what the wiring excerpt for the ignition interlock looks like from the TM1590:
And here is the starting interlock excerpt:
...we will have to look at them together as each shows only part of the picture on why the ignition is killed if you turn on a PTO or take the ground speed out of neutral. Note that in the second diagram there is 12 volts on the key switch terminal S2 (the #710 purple wire) even when the key is in the RUN position. The upper diagram also shows this #710 purple wire, but not why or when it is 'hot' with 12 volts.
In the upper drawing, relay contacts A must be closed to enable the ignition to make spark. IF the transistor C is conducting, as it will be when key switch S2 is hot supplying voltage to TDCM X23 pin 7 via the #705 purple wire, the engine will continue to run -- INDEPENDENT of the seat safety detect enabled at TDCM X22 pin 9. If the seat safety conditions are satisfied, that pin 9 also receives 12 volts, the one-second timeout in the TDCM is inhibited and transistor D also conducts. You must have either transistor C or transistor D conducting to keep the ignition enabled. If there is no 12 volts on connector X22 pin 9, then opening anything in the series circuit in the lower drawing will kill the engine. If your 420 is below S.N. 595881 then you do not have the parking brake switch, but turning on a PTO or moving out of Neutral will definitely remove voltage from key switch terminal S2 and therefore turn off transistor D.
Use a voltmeter to measure what voltage you have at TDCM X22 pin 9 when the key is in the RUN position -- if it is not 12 volts with the seat switch bypassed as you believe it is then there is an open in the wiring on the #800 or #810 pink wires, or a bad fuse at F2 (or an intermittent fuse holder if it is the older plastic tube style...)
Help me here with some feedback of what you actually find on your particular hacked wiring with your observations and voltage measurements and we can continue to troubleshoot if needed. Like Hank says, we can only tell you where to look first -- where to look next is dependent on what you find at each step...
Good luck...
Chuck
Ok, so a few days ago, I get into my TM1590 documentation and start reading through the ignition circuit operation section along with Chuck's comments above and figured I'd quickly try swapping out the TDCM, which had apparently been faulty. It no longer stopped the engine from shutting down when engaging the PTO switch or moving out of neutral. However, the PTO wouldn't kick on. At which point, I figure I'll try another PTO switch ... and the 'new' one fired it up fine. When I first got into this, I'd found a PTO switch laying inside with only one of the 2 sets of wires connected to it. The other "3 connector" end had some little switch from the local hardware store wired to it and mounted in the instrument panel to actually engage the PTO!
So I think I had a bad neutral start switch, a bad PTO switch, and a bad TDCM box. Can I repair the TDCM? If I open up, should I see anything burned out or otherwise obvious? Would just be a matter of a little sodering? BTW, I don't have the brake safety switch on this tractor.
I still have my battery light on ... will try a different regulator when time allows. I think I saw the TM1590 referring to testing whether the stator is good or not ... not sure where. Will try to post my findings. Thanks, Bryan.
So I think I had a bad neutral start switch, a bad PTO switch, and a bad TDCM box. Can I repair the TDCM? If I open up, should I see anything burned out or otherwise obvious? Would just be a matter of a little sodering? BTW, I don't have the brake safety switch on this tractor.
I still have my battery light on ... will try a different regulator when time allows. I think I saw the TM1590 referring to testing whether the stator is good or not ... not sure where. Will try to post my findings. Thanks, Bryan.
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A common failure of the TDCM when a prior owner hacks the wiring is to burn out a diode from excessive currents due to those wiring changes. The diode failure can even happen on stock wiring harnesses if other items external to the TDCM are drawing high currents -- like an internally shorted PTO winding.
In the May 1st postings in this thread are some details on replacing this type of diode.
http://www.wfmachines.com/discus/messages/335/349426.html
You may also find on rare occasions a failed relay or relay contacts that need to be cleaned if water/contamination has entered the TDCM.
There are many discussions on avoiding indiscriminate pressure washing of these vintage machines -- certainly the TDCM is one area to avoid in this regard.
Here is a picture from the above referenced thread on the diode location that may be open...
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Chuck
In the May 1st postings in this thread are some details on replacing this type of diode.
http://www.wfmachines.com/discus/messages/335/349426.html
You may also find on rare occasions a failed relay or relay contacts that need to be cleaned if water/contamination has entered the TDCM.
There are many discussions on avoiding indiscriminate pressure washing of these vintage machines -- certainly the TDCM is one area to avoid in this regard.
Here is a picture from the above referenced thread on the diode location that may be open...
Chuck
Ok, still got somethin' going wrong here. I'd replaced the TDCM and all seemed fine last time I had chance to spend any time on this. The few times I'd since started, it did seem to start with more & more difficulty until now it won't start. I opened & looked at the original TDCM for a 'burned' diode as mentioned above ... don't see anything looking out of the ordinary. I measured approx. 11.75v at the "X22 pin 9 when the key is in the RUN position" with the 2nd TDCM. Decided to swap with yet another TDCM from a parts 316 tractor, and it fired up after a couple cranks! Should've measured the X22 pin 9 again, but didn't think to do so ... try to get that tomorrow. So I'm suspecting that something is trashing the module, but not sure where to go next. There are no fuses on the red & pink wires that would run to the ignition switch ... they had been connected together (see the 2nd pic posted above) ... why, I don't know. The ignition switch has only the 5 connectors, not a 6th. Help! Thanks, Bryan.
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