312-A, PTO clutch, clutch pedal lights stay on, main fuse melted

[urbanmic 0]

Hello all- I've searched all related items I could find in this forum that might help detangle my situation but none have had quite the same issue. My recently-inherited 312-A had a melted main fuse (25 amp). When replaced, the PTO clutch and clutch pedal indicator lights stay on all the time (with the key off) as soon as a new fuse is put in. Once the fuse is inserted, the machine will start, run, mow and operate normally all while having these 2 lights illuminated. The problem I noticed (after mowing for about 1/2 hour) is the fuse is still heating up. I didn't run it long enough to have the same melting issue but it's clear the problem is still there.

I took out the circuit board to look for corrosion, a loose wire or any other such obvious issues. This circuit board is covered in a green protective layer covering the board components. The connection to the wiring harness was a tad dirty for being in place for 25 yrs. but the connection was in great shape. I cleaned it all up and put it back in place and am still having the same issue with the lights staying on. I haven't torn into other safety switches yet(other then a general visible check to make sure there were no frayed/shorted wires or loose grounds) as I thought it might be wise to throw this out there for some possible pointers before tearing everything apart when it may be something that's been seen before. Being that the fuse is overheating, my initial thought would be a ground issue but i'm not sure on that or whether it's related to the warning light problem or not. Thanks in advance for any info.!

[Save Old Iron 1,563]

First step is to replace the fuse holder with a good quality 30 amp (not 20 amp) fuse holder. Corrosion of the fuse holder contacts is inevitable over time. Corroded contacts are responsible for creating heat in the fuse holder body as battery charge current flows thru the holder contacts.Cleaning the fuse holder contacts can provide temporary relief but replacement of the fuse holder is the only long term solution.

If additional problems remain after the holder replacement, we will adress those too.

p.s - the indicator board does just that - only indicates voltage levels present at safety switches - rarely (if ever) does the indicator board cause cranking or ignition issues. The tractor will function properly even if the indicator board is removed.

[urbanmic 0]

Thanks much SOI! My next move was exactly what you had suggested---- replace the fuse holder with a good 30A one. No doubt the heating up of the replacement fuse was was perpetuated by the damage caused by the previous meltdown. So I did replace that, gave her a good 45 minute cutting session and the fuse was cool and calm after shut-down. Those 2 indicator lights still stay on with the key off so I'll stick with the easy "fix" of simply taking out the fuse when I'm done cutting and putting it back in next time. Glad to hear having those lights on isn't going to be more of a visual nuisance (if you will) and won't affect functionality or anything else.

While I'm here SOI, I've read through tons of posts to many of which you've provided clear, insightful, and complete solutions to a myriad of sometimes easy and sometimes difficult issues that both novice and seasoned DIY'ers come across. Equally as important, you've reminded others to take a step back, think through the situation first and don't overlook the obvious. I've been doing my own work on all types of machines for over 20 yrs. now and sometimes I need a reminder to not get overwhelmed and follow a logical process for fixing a problem. Kudos to you for your time, patience and providing volumes of knowledge to help those in need!

[Save Old Iron 1,563]

You are too kind sir.

I do what I can to help.

[Save Old Iron 1,563]

Another issues that just struck me is you need to remove the 25 amp fuse to turn off the indicator lights. I would assume the lamps should be powered off when the ignition switch is turned to the off position. From a quick look at the 312-A schematic, there should be ORANGE wire connected to the (+) terminal of the Voltmeter (or optional Hourmeter) which heads up to pin #2 of the indicator board. This ORANGE ?? wire should carry the power to indicator ONLY WHEN THE IGNTION SWITCH IS IN THE RUN POSITION.

Sooooo.... Let's start here

if you have a test light or multimeter, with the ignition switch turned off

1/ look at the tractor voltmeter - is it still indicating battery voltage ? There should be no voltage indicated on the meter.

2/ measure the voltage at the pin #2 on the indicator board (orange wire) - the voltage should be zero (no power to the indicator pcb). If there is power to the voltmeter or the indicator board with the ignition system off, we have a wiring issue.

[urbanmic 0]

Going to check this out as soon as I get it back from a friend who has it on loan. His mower died and I decided to let him use the 312 until everything is squared away. I'll be looking forward to have the opportunity to dig back into this and see if I can't get to the bottom of things! thanks again for the help!