Welded and now it won't start.

Mundy · Feb 27, 2010

I had to weld something on a snowmobile trailer today. I hooked to it with the tractor and pulled it into the barn. Did my welding and went to start the tractor and I have no power.
It never crossed my mind to disconnect the trailer.

This is a 1981 Mitsubishi with very simple wiring. Alternator/voltage reg/ starter/glow plug
1. I checked main fuse and it is fine. I even swapped it just in case.
2. I still have head lights and the temp light on the dash but the gen and oil light no longer light up with the key on.
3. there is no click or anything when the key is turned.

Does anyone have any sugestion of where to start looking?

carpenter383 · Feb 27, 2010

Yup it's not a good idea to weld on a machine without unhooking the batt.
Have you checked for voltage at the starter solenoid?
Are there and saftey switches that could keep the starter from cranking?
You might check for a fuseible link somewhere in the starter solenoid wiring.

mustangsallysdad · Feb 27, 2010

carpenter383 said:
Yup it's not a good idea to weld on a machine without unhooking the batt.
Have you checked for voltage at the starter solenoid?
Are there and saftey switches that could keep the starter from cranking?
You might check for a fuseible link somewhere in the starter solenoid wiring.

Yeah...sounds like a fusible link or a diode.

captaincrab55 · Feb 27, 2010

mustangsallysdad said:
Yeah...sounds like a fusible link or a diode.

Wouldn't a diode be a charging issue instead of a starting problem???

banjodunn · Feb 27, 2010

G'day if you have got lights etc then i do not think you have got a fuse prob it sounds to me like you have got a safety switch or possiby an ign switch failure and i think that this woud be purely coincidence to the welding. If you had a late model computer driven machine then i would suggest that you disconnect battery or fit an anti zap unit when welding however many times i have welded to machines and i am yet to have a prob maybe i am just lucky but i do take care of where i position the earth ( sorry ground for you over there

) and i make sure i have it as close to the wed as possibe and make sure it is cean. Getting back to your prob i would look for probs as i said earlier you would be very very unlucky to have caused the prob through welding

Jon

captaincrab55 · Feb 27, 2010

Mundy, Does your Tractor use a relay in the safety circuit???

mustangsallysdad · Feb 28, 2010

captaincrab55 said:
Wouldn't a diode be a charging issue instead of a starting problem???

Regarding a diode being a charging vs. a starting issue...Not necessarily...if it can't start, it can't charge. The corellation being that there is most often a diode in series with the starter motor, starter relay, a slow blow fuse (fusible link), fuse box and the assorted safety relays. A low-impedance short in the diode could be caused by "current bunching" from welding backfeed. Doesn't take much current (ma)to melt the silicon in a diode.

captaincrab55 · Feb 28, 2010

mustangsallysdad said:
Regarding a diode being a charging vs. a starting issue...Not necessarily...if it can't start, it can't charge. The corellation being that there is most often a diode in series with the starter motor, starter relay, a slow blow fuse (fusible link), fuse box and the assorted safety relays. A low-impedance short in the diode could be caused by "current bunching" from welding backfeed. Doesn't take much current (ma)to melt the silicon in a diode.

Tell me more about a diode in series with the starter motor.. I'm in a learning mode today....

mustangsallysdad · Feb 28, 2010

captaincrab55 said:
Tell me more about a diode in series with the starter motor.. I'm in a learning mode today....

I realized he has a 1981 model tractor and from the sound of it non-transistorized ignition and probably mechanical safety linkages as opposed to electrical safety relays...so I doubt there are any diodes other than perhaps in the alternator...his problem is probably a lot simpler than I was thinking...there's usually a blocking diode between the safety relay circuits or seat switch and the starter relay on the newer tractors.

deepNdirt · Feb 28, 2010

remove and clean both ends of both the ground Battery & frame and pos+connections at the starter as well as the battery, what might have already been a weak connection may have gotten worse when the welders ground found its way through the tractors ground system, the grounds are as equally important as the Positive lead connection, in fact I've found that in most cases of troubleshooting a starting issue 80% of the time it winds up being a bad ground,
good luck!

Mundy · Feb 28, 2010

I will be tracing voltage today to see where it stops.
The only safety switch is the clutch switch but I am pretty sure the problem is before that due to the gen and oil light not being powered.
I am leaning toward ignition switch.

wushaw · Feb 28, 2010

It does sound like a fuseable link there somewhere maybe. Also check your ground, I know mine was attached under the dash and it was a bad place, it corroded and was loosing connection. I relocated it to the eng block.

northernguy · Feb 28, 2010

My Mitts has a switch on the high/low range lever,and it stopped mine from starting (has to be in the neutral 'center'to crank),unplug the two wires going to the switch and plug them together,someday I'll adjust my switch but bypassing it is quik and should get your starter cranking.

Matt_Jr · Feb 28, 2010

I weld on all kinds of cars and trucks without disconnecting the battery. Usually on exhaust, frames, and hitches. I've welded on vehicles built from the 30's to today, making custom exhaust and frame repairs etc.., and the only time I've had a problem is when I used an oxygen sensor as a ground. Burnt the heater circuit in the sensor itself, and had to install a new one. That's it. Never had an airbag go off, alternator fail, or anything else. My guess is welding on the trailer had nothing to do with Mundy's tractor not starting unless he grounded his welder on the tractor where a critical part (starter, ignition switch, fuses) were between the welders ground and electrode. If the welders ground was on the trailer it had nothing to do with the tractor not starting. Electricity takes the easiest path, and welding is no different. I would, like others have said, start checking safety switches, battery cables, the starter itself(including solenoid), ignition switch, or fuses. Good luck Mundy.

Eagleview · Feb 28, 2010

Even though you forgot to unhook the tractor or the battery lead , I think it is a coincidence that it is not starting . You would have had the welders Earth lead on the trailer where you were welding so the current can't really harm the tractor . It could only do it if the welders Earth lead was hooked to the tractor and you would not have done that .

Mundy · Mar 1, 2010

Well, the wife trumped any tractor repairs with honey doo's so I don't know anything yet.
The ground lead was hooked to the trailer but the bucket was full of snow and sitting on the floor, I don't know if that could have provided a ground route for the welder or not.

easygo · Mar 1, 2010

I just recently welded on an implement while it was attached to the 3ph. Only after I was done welding did I realized that I may have done something stupid, but nothing happened. I had the ground about 10" from the weld. Tractor (2004) started right up.

Steve Bosshard · Mar 2, 2010

Just to be sure I have a clear picture, You placed a machine on a trailer, Used your tractor to pull the trailer with machine to your shop to weld something on the machine on the trailer. You hooked the ground clamp from the welder to the machine on the trailer, did your welding, unhooked, and now the tractor on rubber tires not touching anything other than the trailer won't start ?

If this is so, I believe the won't start is a coincidence like a couple of other folks believe and would look for the usual suspects like a corroded battery cable end, etc. Sure hope it is a simple fix.

Wish you the best, Steve Bosshard

Mundy · Mar 2, 2010

The trailer is what was welded.
The ground was conected to the trailer and 4 welds were done to attach tie down rings on the trailer.
The tractor has a 2 " ball mounted to the loader bucket. The trailer was latched to the 2" ball and the loader bucket was full of melting snow.
There seems to be no way stray current could have made its way throught the tractor but?

I have traced it to the point I am going to have to take the dash apart. The power is good at the starter and alternator and going to the dash but only comes back out of the dash at the lights. So I believe it is either in the key switch or the voltage regulator. I can't get to them well enough to test without taking the dash apart.

Steve Bosshard · Mar 2, 2010

A resistive cable end can show a good 12 volts until there is a load. Sears Service used Motorola Micor 2 Way radios. Two or three days after a rain several vans would come by for service. No transmit. Many of the vans leaked water and the jute padding under the floor mat would get soaked. The Micor used 2 power leads (plus a heavy 30 amp circuit for the power amplifier). The ign sense wire enabled the radio transmitter. Invariably there would be a butt connector crimp splice under the floor mat. There was enough power to run the receiver but when the transmitter was keyed the transmit enable lead would drop to 3 or 4 volts under load due to electrolysis in the wet butt connector. New splice - tape and seal against moisture and away she went. Also aluminum power taps onto a copper battery cable would do similar on the 30 amp circuit.

Don't let a 'good' voltage reading deceive you. Of course there may be other problems, but I would sure look for cable end / loose connections first. Again best luck to you, steve