520-H Headlight fix

[mrblackwell 0]

Hey guys,

Long time lurker, first time posting.

The headlights on my 90 520-H haven't worked since I bought it a couple of yrs ago & I finally decided to find out why. I never mowed at night, so I never needed them, but, I'm going to do a restoration on it & want everything to work.

First off, the old bulbs were broken, so I have put new bulbs in & they will light up when you hook a battery charger to them, so I know the bulbs are good.

I have no power at the headlight switch or anywhere else in the circuit.

I downloaded the headlight circuit diagram from the Toro website & it is showing two fuses & I am only finding one 15A fuse. It is not in the main fuse block, but in a separate fuse holder & it is good.

Anyone know where the mysterious second fuse is located or should I be looking at something else as the problem ?

Thanks in advance for the help.

[Save Old Iron 1,571]

Two things to consider before you start tracing out wiring.

You need both 12 volts AND a good ground connection to lite the lights !

If you have an ohmmeter, ,measure the resistance from the terminal on either headlight to a good chassis ground.

If you get an open circuit (infinite resistance), you have lost the ground connection from the headlamps to the chassis. Trace out and repair the open circuit on the BLACK wire side of the headlights.

If you get a few ohms resistance on the GREEN wire connection to the headlights, your ground is good and you need to investigate where the GREEN wire for the headlight disappears back into the tractor.

With other owners of the tractor having the ability to modify the wiring of the tractor, the fuse holder could have been swapped out years ago and could actually be anywhere in chassis of the tractor. Check up along the battery compartment or down near the front right wheel near the hood hinges for the original fuse holder(s).

Also, check for proper operation of the tail lights. If they are out too, this could indicate a light switch issue OR the taillights have their own wiring issues too. Some of the wiring I've dealt with in these tractors defies logical troubleshooting, Sometimes you have to dig in with eyes open and voltmeter ON !

I know you said the headlights lite, but I'm not sure if you used a battery charger connected directly to just the bulbs themselves or it you hooked the battery charger to the wiring connected to the bulbs. The first way just checks the bulbs, the second way checks the wiring and the bulbs.

[Operator 7]

Our 520's have three fuses in the fuse block on right side cowl and one of them is for headlights. On yours do the tailights work? You said you have power at switch, on the "in" side which will be hot all the time or on the "out" side which will be hot only when you turn light switch on.

Randy

[mrblackwell 0]

Randy, I do not have power to the switch.

Tail lights do not work.

On your tractor, which fuse in the main block is for the headlights ?

Old Iron, I know hooking the charger directly to the bulbs only checks the bulbs, which is what I was checking, as I've seen plenty of "new" bulbs be bad. Just wanted to make sure they were good.

I plan on checking the resistance, but I still need to find the other fuse first. I really feel like the fuse or the switch is the problem.

The wiring has not been modified & the ground is good.

Thanks for the replies. There is definitely a wealth of knowledge here. :D

[Duff 206]

...even though the wiring hasn't been modified (or maybe because the wiring is original) and you have a good ground, check for corrosion in/at the connectors and fuse holders (once you've found the missing one). This is a fairly common problem among the Horses and can lead to a range of electrical issues.

Duff :D

[Save Old Iron 1,571]

I looked on my 520 last night,

A PINK wire brings the power to the light switch from the fuse holder.

The fuse holder (15 AMP) is clipped to the frame support near the battery tray - sitting on the tractor , it's on the right side of the battery.

Don't overlook the fact someone may have replaced the 15 amp fuse with a different value fuse. You may have to trace the holder out visually if a 15 amp fuse is not in the holder.

I would start tracing out some PINK wiring.

Keep up updated. :D

[MikesRJ 558]

Keep up updated.

Me thinks he stutters ...

Keep us updated, mrblackwell.

[Save Old Iron 1,571]

yeah, what he said ....

[mrblackwell 0]

Hey guys, just wanted to let you know that I haven't had a chance to fool with it much. Haven't needed the lights anyway. Hopefully, I'll have time to dig into it in the coming weeks.

I did find out that the wiring HAS been tinkered with in the past, as one of the terminals in the fuse block has been bypassed. Found it the other day when I was dealing with an intermittent "no spark" issue. (I think I had previously said that it was unmolested. Oh well.)

Fuse block also gets awfully hot after running for maybe 30 seconds. I'm thinking it's time to replace the fuse block with weatherproof ones.

Of course I could always unbolt the fuse block, hold it while mowing & just give it a good shake when it starts to cut off, but that would require putting down my beverage

Dang, I just got off topic & hijacked my own thread.

[bmuone 15]

I believe you have your problem well in hand.....

[Save Old Iron 1,571]

mrblackwell

thanks for the update, its always good to see the root cause of the problem and the photo of the fuse tells it all.

If you hunt down individual weatherproof fuse holders, search out the 30 or 40 amp versions only. They are a little beefier than 20 amp holders.

I also believe you can purchase the individual fuse holder contacts to replace them in the current fuse holder. :thumbs:

[mrblackwell 0]

Yes, you're right about the contacts. I actually found the correct fuse block with the contacts for 15.00, but I'm still not sure whether to go with it, or the weatherproof.

Anyone know what could be causing the fuse block to become so hot in that short amount of time ? :thumbs:

[Save Old Iron 1,571]

Go weatherproof if for no other reason than the length of wiring that comes with the fuse holder.

As you strip back the insulation on the wiring on the current overheated fuse contacts, the wiring will be oxidized and present further high resistance issues if you just crimp dirty wires into a new fuse terminal.

With the fuse holder with wiring attached, you will have the opportunity to cut back the oxidized tractor wires a few inches to get to a clean, easily solder-able connection to the fuse holder. A littel color coordinated heat shrink tubing and you have a professional quality fix. :D

[Save Old Iron 1,571]

Anyone know what could be causing the fuse block to become so hot in that short amount of time ?

That's a n easy one - has showed up many times on this site.

High current flows thru the fuse holder - a resistance develops due to corrosion of a fuse blade or fuse holder terminal,

in electronics, wattage (heat) is calculated by a simple formula involving current, resistance and voltage.

The more corrosion , the more resistance, the more heat developed at the area that is corroded.

By my calculations, even a small resistance on a 30 amp circuit can develop heat equivalent to a small soldering iron.

Good troubleshooting :D