Case 580 Super L, won't start, 12V on ignition switch drops to 0V when switch is on.

Good afternoon! I hope someone can point me in the right direction because I am at my wits end.

I have a Case 580 Super L, 4x4, that will not start. It does absolutely nothing when you turn the ignition switch to "ON", and will not crank.

The battery is good, I even hooked up jumper cables to a second battery and I still had no response at all. No lights/horn/instruments/anything.

When I check for power on the ignition switch I have 12V, but when I turn the key to "ON" the voltage drops to 0V. Turn the key back off, 12V returns to the power wire on the ignition switch.

I checked the function of the switch with a multimeter after disconnecting it and it seems to be operating ok. I also tried jumpering the 12V wire on the ignition switch to the wire that powers the accessories, and to the wire that should make it crank, all to no avail.

I pulled, cleaned, and added dielectric grease to all the fuses and relay posts. I swapped around relays. Still no power to anything despite it being at the starter post, ignition switch, and the power block below the relays/fuses.

I cleaned out all the nooks and crannies in the engine bay and under the floor plate to look for broken/chewed through wires...nothing seemed out of the ordinary although something certainly had been living in the space just behind the motor compartment, above the transmission. Tons of grass and twigs in there but all looked fine after cleaning. I tried to check the neutral safety switches but I cannot seem to find any information on where they are. Plus I would assume if a safety switch was bad I could still turn on the lights and such.

Lastly, a bit of information on the unit. About a year ago it exhibited these same symptoms, but then the issue resolved itself after a few minutes. It has been fine ever since...until yesterday. I was loading the backhoe on a trailer to move it, started fine, ran fine, loaded fine. I turned it off. I then realized I needed to reposition the boom a bit, so I went to crank it over again and it cranked super slow as if the battery was almost drained, then nothing. No noises, smells, sparks, etc. All of a sudden nothing worked. Further turning of the key in the ignition did nothing.

So now the backhoe is sitting on a trailer, can't take it off, can't get it to run. Has anyone ever had something like this happen? I'm sure it's something simple and electrical, but I cannot find it and it doesn't help that there is virtually no information on this unit online. I cannot find a wiring diagram to save my life! So any help would be greatly appreciated. I have got to get this thing moving.

I can't help with specifics of the machine but I can tell you that you've fallen into the trap of using a digital multimeter to trace voltage with. A DMM needs virtually no current in order to work so will see 12v through, for example, a badly corroded connection.

Get yourself an old school test light with an incandescent bulb (not LED) or make yourself one with a headlight bulb and wire. Your troubleshooting will go much better.

Welcome to HEF, BlueDog !
Send me your email address in a PM (private message) and I will send you the electrical schematic in .pdf.
You will find tho that it is quite intricate to read.
You probably should buy a service manual.

Cmark said:

I can't help with specifics of the machine but I can tell you that you've fallen into the trap of using a digital multimeter to trace voltage with. A DMM needs virtually no current in order to work so will see 12v through, for example, a badly corroded connection.

Get yourself an old school test light with an incandescent bulb (not LED) or make yourself one with a headlight bulb and wire. Your troubleshooting will go much better.

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Yes sir I have one! I use it in certain situations...this situation it isn't doing me much good due to the nature of the problem. This is a strange one.

Tinkerer said:

Welcome to HEF, BlueDog !
Send me your email address in a PM (private message) and I will send you the electrical schematic in .pdf.
You will find tho that it is quite intricate to read.
You probably should buy a service manual.

Click to expand...

Thank you! That is just what I need. And yes, I have manuals for my other equipment, this was a newer addition and I just haven't gotten around to it. I never really need manuals for mechanical fixes as I have a lot of experience in that department...although I usually end up buying the manual just to be safe.

But despite being in electrical engineering for 15 years, I still haven't developed the ability to look at a huge collection of wires and know what does what ha ha! And boy does this 580 have a lot of them. I generally like to stick with simpler machines but the backhoe is very useful, so here we are!

Try checking/tightening the ground strap off of the battery to the frame. Then check ground strap inside of the frame by the battery box to the engine/trans. Tighten the bolt for the wiring on the starter.

highwayghost said:

Try checking/tightening the ground strap off of the battery to the frame. Then check ground strap inside of the frame by the battery box to the engine/trans. Tighten the bolt for the wiring on the starter.

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I pulled the starter, checked it, cleaned and retightened all the connections including the ground strap that runs to the engine, but I didn’t clean and retighten the one directly from the battery bc it was very secure, but for the sake of doing it I will remove and clean the ground strap from the battery to the frame as well bc you never know! Thanks for the suggestion!

I agree with cmark, and highwayghost. From what I've read it sounds like a bad battery ground or bad connection on the harness that goes to the ignition switch. Your meter will show 12v but not current. If you are losing power while cranking that means that the wire supplying voltage to your ignition switch isn't carrying the load. Usually caused by bad ground or connection. Good luck and I hope you find the problem soon.

If you have good power at the starter, for a temporary work around, connect a 12v+ wire to the single wire on the injector pump to energize the fuel shutoff solenoid. Then jump the small single wire on the starter to the large starter post. This will engage the starter and the engine should start so BE CAREFUL!!! Take all safety precautions. Depending on what is wrong you may or may not have power to the shuttle shift. This may allow you to get it off the trailer and to a better work spot.

BlueDogDozing said:

Yes sir I have one! I use it in certain situations...this situation it isn't doing me much good due to the nature of the problem. This is a strange one.

Click to expand...

This is not really that strange. Relays,fuses,connections can all cause this and all can show proper voltage until a load is applied. Start close to the battery and work away from it with the test light-not the multimeter- following the the wiring diagram. This machine doesn't have any electronics that a test light can damage

jumper positive strait to starter, also do negative and see if the starter spins over

Paul Council said:

I agree with cmark, and highwayghost. From what I've read it sounds like a bad battery ground or bad connection on the harness that goes to the ignition switch. Your meter will show 12v but not current. If you are losing power while cranking that means that the wire supplying voltage to your ignition switch isn't carrying the load. Usually caused by bad ground or connection. Good luck and I hope you find the problem soon.

Click to expand...

I'm losing power as soon as I turn the key to the "ON" position, never mind cranking. If I try to crank I get nothing as well. Nothing that should have power from the key being turned on has power at all. The 12V signal at the ignition switch is present until I turn the key "ON". I suspected a relay because of that, but I've checked, cleaned, swapped around the relays to no avail. I'm starting to think something is grounding out as soon as I turn the key to the "ON" position.

I will be checking the rest of the grounds and such tomorrow as I ran out of light...and patience for today. Also, a kind soul sent me the electrical schematics so I am looking them over now to try to find points that could cause this.

If you think of anything else, let me know, and thank you for your help!

Bad key switch? Or power relays at the fuse panel? The shuttle shift lever has a neutral safety?

highwayghost said:

If you have good power at the starter, for a temporary work around, connect a 12v+ wire to the single wire on the injector pump to energize the fuel shutoff solenoid. Then jump the small single wire on the starter to the large starter post. This will engage the starter and the engine should start so BE CAREFUL!!! Take all safety precautions. Depending on what is wrong you may or may not have power to the shuttle shift. This may allow you to get it off the trailer and to a better work spot.

Click to expand...

I do have good power at the starter. I pulled the starter and tested it out of the engine so it wouldn't turn the motor over as it's on the trailer still and I didn't want to risk it moving by accident. I will have someone who can help me tomorrow so I plan on taking your advice here...although I am pretty sure the shuttle shift won't have power, so I don't think I will be able to move it. So long as the hydraulics are working I can lift the boom back up into the transport position, then I can winch it off the trailer if I can't drive it. As it sits now I can't even pull it off the trailer, the boom would just hit the ground

highwayghost said:

Bad key switch? Or power relays at the fuse panel?

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I thought about that...so I disconnected the wire harness to the ignition switch and tested operation of the switch...it behaved as it should. I then jumped the ignition switch wire harness to see what happened and it did the same thing as when I turned the key...nothing...

I also cleaned and swapped out the relays thinking that if it was a relay that would solve the problem. It didn't have an effect.

You can access the shuttle shift harness and plug by removing the glove box ahead of the steering wheel.
Check the neutral relay or other relays that are suspect to the problem. On my neutral relay, the connectors on the relay panel pushed in when the relay was installed and lost contact. Had to unbolt the panel to access the backside for the repair.

If you check for voltage at the starter power post, does this voltage disappear just as it does at the key switch when the key switch is turned on? If no , then you have high resistance in the power feed wire to key switch. If yes then you have a bad connection at the battery or high resistance in the cables, positive or negative. It will be something simple when you find it.

partsandservice said:

It will be something simple when you find it.

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I Agree... The simplest and most obvious things can often cause the most trouble... Double check that battery. Replace with a known good... Possibly has an internal short.

You are not losing voltage. You are measuring potential in an open circuit. Once the circuit is complete the voltage drops to zero volts because the circuit can’t supply the amount of current needed to make it work.

You have high resistance in the 12 volt supply to the ignition switch. You can test the circuit by connecting 12 volts direct from the battery to that terminal on the ignition switch and then trying to crank. Once you prove that this corrects your issue you can look for where you are getting the added resistance. You will find corrosion most likely somewhere in the power supply wire.

you problem is simple electrical diagnosis. You need to understand the difference between potential in an open circuit vs. voltage in an operating circuit. If you don’t understand how electricity work it is very confusing. uys here will help you

I'm an electrician. For 50 years now other people have paid me to solve their electrical problems. I usually solve, or diagnose effectively. Mostly I deal in higher voltages than this, but I've had a ton, or (more accurately) hundreds of tons of experience with 12 volt failures on machines I own.

I've learned two constants about 12 volt systems:
If a bad connection exists, it'll come to failure exponentially sooner than with higher voltage.
If someone before me found the problem, they made a makeshift repair, and it failed again.

I own a 580K. I've had numerous electrical fails. Almost all have been the result of failed connections. I absolutely agree with Cmark. A voltmeter won't help you here. A voltmeter doesn't test under load. A high wattage incandescent bulb rigged with test leads is more effective.

Backhoes suffer environmental stress. They live outdoors, they are used in foul weather. The Case 580 series were built in several configurations. Wiring harnesses were in four or five sections. Big multi terminal plugs are located at the bottom of where dirty, maybe corrosive water will drip down the wire.

Every point where wire is cut, several opportunities for bad connections exist:
Where a wire receives a crimp terminal, it oxidizes inside the crimp.
The terminal oxidizes, or gets dirty.
The wire meeting it is subject to the same stresses.
Every point where an equipment circuit uses the iron of the machine as a conductor, it requires a good connection to "ground".



Now I expand my rambling to a distant tangent. December 2016 I bought a bulldozer. The seller delivered it Christmas day. My wife was not pleased.
We put it in the shop and went through it. Along with 25 other fixes, we put a new starting system in. Starter and alternator went off to the best rebuilder on Earth. All new cables, with all new terminals were installed. A new master switch, new solenoid, and new batteries. Everywhere castings mating conduct electricity, new holes were drilled and tapped, or a bolt was removed ground clean, coated in "Noalox" and clamped. All connections, terminals, were new, and treated with corrosion inhibitor, including inside the crimps of crimped connections.

The Dresser TD7G was miserable to start cold. Numerous times I would remove the batteries, charge them, and warm them overnight, put them back. It would start perfectly!

One day at 5 degrees F I was at my limit. Newly charged & load tested batteries failed to start it. I went through the system with a volt meter on each side of each connection, under load. Many of these connections were located where you have to unbolt lots of stuff to get to.

Removing the seat, the plating it bolts to, I discovered a new bolt, new terminal, fully polished, and treated with corrosion inhibitor, but the nut was only started! I knew instantly what went wrong! The phone rang.
My son receives 50 phone calls a day. When he hangs up, he hurries to make up for lost time. He forgot to tighten the bolt. We had endured years of hard starting for failure to tighten a nut.


My 580K has one key. It lives in the switch except when a child will be here, then we put it away. Seth & I usually know each other's hiding places. Zack (second son) isn't always kept informed. Everybody knows to hot wire it you pull a white wire out of a seven wire plug, touch it to batt+ on the ignition switch, after it starts, put it back where it came from.

Zack had been here, wanted the backhoe, hot wiring didn't work. He put the white wire back in the plug, went on with his day. He didn't mention it to anybody.

I next used the machine. With a key it started, but stalled immediately. On starting fluid it would run. No fuel. I traced the problem to power at the injection pump inflow valve until it started, then it died.

Examination of schematics showed the white wire from ignition switch to injector pump was plugged into the wrong terminal at the ignition switch.

Electrical issues are frustrating. Knowing where current should be flowing is essential. Power flows from negative to positive. Follow with a high wattage test light, or across each connection with a volt meter. If potential should be zero across a connection, but you have voltage, fix that.