Electrical issue and question

[Code54]

We have an old mule (1985) that ran good until last night. I pulled the plastic off to clean it all up and when I went to start it today - nothing....
Not a crank, nothing. Thinking it was a loose connection somewhere, I checked them all. Cant find anything. Checked the brake interlock - seems fine. Put a 12v tester on the battery (the simple one with just a light) and nothing - no light. Ok, the battery is dead - pulled it out and put my ATV battery in to start it - nothing. Put the tester on the ATV battery while it was hooked up -nothing. OK, the ATV battery is brand new and just charged up. Took the battery out and tested it - light right up. Hook the Mule cables to it, NOTHING and will no longer light up. Tried to jump start the Mule - smoke - I know that is not good. Found where the fuse blew and replaced it. Still nothing.
I have no idea what could be wrong. The only electrical things I touched removing the plastic was the on/off switch for the front lights and the key switch - both are just plug in harnesses so nothing real tricky. Any idea what is going on and what I need to check? Could the Cdi box have suddenly went? (it basically has a 10HP Kaw. motor )
Thanks for any ideas as Im stumped

 

[Code54]

Not sure if I wrote that clear, but when the Mule's battery cables are hooked to the battery I can't get the tester to even light. Never had this happen and seeing I couldn't find a bad safety switch (not many in 1985) I'm really stumped

 

[Johnny g]

Are you putting the test light on the battery terminals or on the cable ends attached to the battery? maybe corroded cable ends?

 

[timswi]

First guess is that the main ground is bad...Try manually grounding the battery and re-test.

 

[Code54]

Thank you both.

I was putting the light on the screws of the battery. But no light????

By manually grounding it I am gassing you mean run a wire from the neg straight to the frame?

The part I just can't understand is it worked fine 24hrs before and I never messed with the battery/electrical - just took the switch out of the plastic.

 

[timswi]

Thank you both.

I was putting the light on the screws of the battery. But no light????

By manually grounding it I am gassing you mean run a wire from the neg straight to the frame?

The part I just can't understand is it worked fine 24hrs before and I never messed with the battery/electrical - just took the switch out of the plastic.

Yup, just clean up a place on the frame and temp ground it to see it that's the cause..I like cleaning my stuff like that too, but sometimes it creates more problems than it solves..The most reliable used vehicles I've ever bought had the beejeebers beaten out of them. The most un-reliable, the ones that were over maintained..Why?--I can't say.

I take care of my stuff anyway..

 

[Scrambler82]

Did you say you rechecked the connection on the key switch ?
The battery should show full voltage if you test across the poles !
Is there anything like a battery minder in the circuit ?

Test light should be positive to frame.

Take a continuity tester, and check the cables from end to end.

Why it worked 24 hours ago and not now is a hard question to answer, you need to review all of the connections you played with. If there are connectors you need to check the pins on both ends, some may have unlocked and slips and/or some may be broken.
Not a lot could change in the time frame you are stating other than something going wrong with what you touched.

Luck on your search.

 

[mjw357]

Is this a side post type battery? The fact that a fully charged battery will not even light a test light tells me you aren't getting a good connection with the cables.

 

[timswi]

One more thing--I've had ground cables rot out and separate under the insulating cover..Just FYI.

 

[Scrambler82]

Is this a side post type battery? The fact that a fully charged battery will not even light a test light tells me you aren't getting a good connection with the cables.

Sometimes the strip connecting the side posts are weak and break or burn up... but you did say you used another battery to check.

 

[mjw357]

Sometimes the strip connecting the side posts are weak and break or burn up... but you did say you used another battery to check.

The way the side post connectors are made, even if the bolts are tight, they still may not make good contact with the metal part inside the end of the cable. Lots of space for dirt and corrosion in there. I am betting there is an issue with the cable.

 

[Code54]

View attachment Mule 500 elec system.pdf

First: Thank you all for your ideas and help!

I am using top mount cables (just uses a phillips screw into a nut on the underside of the terminal. - ATV style battery)

The only connector I touched was the key switch (unplugged it) so I was thinking that must have been my problem but I checked it several times and can find no issues there.

What really scares me is when I went to jump it (when i thought the battery must be dead - bad idea by the way) the wires smoked for a brief second. Not sure what ones but may have been the cable or there is a second smaller wire that runs from the positive terminal (with the main red wire)into the loom but that has a fuse. I blew the fuse when I first went to jump it and replaced it with another fuse of the exact same size and did not have a problem again.
I been looking at the online wiring parts list and it is simple enough. I attached it for your reference.

Tomorrow I will clean all the contacts, wire connections and frame termination points. try to triple check the switch connection and pray it runs :thumbsup:

 

[Code54]

Here is the update - Had a few minutes today and looked at it a bit more.
Still not working....

Put new ends on both of the battery cables and even redid a few splices that looked old and well worn. Red from battery goes straight to the starter and the black runs right to the bottom of the motor and grounds everything. Cleaned those connections also.

The small wire that attaches to the positive goes straight into the harness and it appears runs to the key switch. A small black wire that is on the negative post heads to the frame as a ground and is pigtailed off and that goes into the harness also. I followed all the wires I could and could not find anything tore up or damaged.
I did trace some small wires to a relay (guessing for the start circuit) so I checked with NAPA and got a new relay (for $10 figure it was worth it just due to the age.).
The only thing left in the circuit is the rectifier - not sure if it is good or bad at this point.....

I put the battery on the trickle charger and will let it sit for the next day and get up to full charge. Cleaned everything I can clean so once the battery is charged I will give it another go.

I am really stumped on what happened to the machine......

 

[k0ua]

Do this,
step 1: go buy a good voltmeter. They don't cost that much.

Step 2: Re install the charged battery.
Step 3: Hook back up the positive cable and place red lead of voltmeter on the terminal connection of the battery. Black lead on the negative battery terminal Reading should be at least 12.6 volts if it has come off of the charger recently. Remember you don't have the black ground lead of the machine hooked up yet. You may need a helper or 4 hands to complete this next step.

Step 4: Momentarily touch the ground to the negative lead while still taking the voltage reading with the meter and watch what happens to the voltage. NOTHING should happen, it should not draw any current, and the voltage should still be 12.6 but I suspect you will see one heck of a voltage drop and a fairly large arc. If that is the case you will have to find out what is drawing current. Alternator diodes bad?

Please try these things and report back.. This is simple scientific method diagnostics.

 

[timswi]

Here is the update - Had a few minutes today and looked at it a bit more.
Still not working....

Put new ends on both of the battery cables and even redid a few splices that looked old and well worn. Red from battery goes straight to the starter and the black runs right to the bottom of the motor and grounds everything. Cleaned those connections also.

The small wire that attaches to the positive goes straight into the harness and it appears runs to the key switch. A small black wire that is on the negative post heads to the frame as a ground and is pigtailed off and that goes into the harness also. I followed all the wires I could and could not find anything tore up or damaged.
I did trace some small wires to a relay (guessing for the start circuit) so I checked with NAPA and got a new relay (for $10 figure it was worth it just due to the age.).
The only thing left in the circuit is the rectifier - not sure if it is good or bad at this point.....

I put the battery on the trickle charger and will let it sit for the next day and get up to full charge. Cleaned everything I can clean so once the battery is charged I will give it another go.

I am really stumped on what happened to the machine......

Did you continuity test the ground? Hate to be a broken record but ---

 

[Code54]

I have tested the ground and everything came back good. (well I think so at least - below will explain it more)

I have a good volt meter and just know enough about it to be dangerous.... Never had a seconds worth of training on it, pretty much been figuring it out as I go - Not the best but better than nothing I guess.
I am working all day tomorrow and doubt I will make it back in time to check it but will hit it Jan 1 for sure!
Thanks for the advise and please don't worry about over describing things as I am just learning and maybe doing something wrong and not even know it.

 

[timswi]

I have tested the ground and everything came back good. (well I think so at least - below will explain it more)

I have a good volt meter and just know enough about it to be dangerous.... Never had a seconds worth of training on it, pretty much been figuring it out as I go - Not the best but better than nothing I guess.
I am working all day tomorrow and doubt I will make it back in time to check it but will hit it Jan 1 for sure!
Thanks for the advise and please don't worry about over describing things as I am just learning and maybe doing something wrong and not even know it.

..

Dude, it's all good--Ain't no electronics guy myself..Just suggesting what I've seen..:drink:

 

[Xfaxman]

-----------------------

I have a good volt meter and just know enough about it to be dangerous.... Never had a seconds worth of training on it, pretty much been figuring it out as I go - Not the best but better than nothing I guess.
I am working all day tomorrow and doubt I will make it back in time to check it but will hit it Jan 1 for sure!
Thanks for the advise and please don't worry about over describing things as I am just learning and maybe doing something wrong and not even know it.

This might help: Multimeter Tutorial

 

[Code54]

Thanks Guys!

Most of my learning on this type of stuff comes from the net and sitting in the shop trying to figure it out so your help is greatly appreciated!

 

[k0ua]

This might help: Multimeter Tutorial

this ought to be a sticky!