Bobcat X331 compact Excavator electrical issue!

[Daniel.]

Dear knowledgeable mechanics. I could really use some assistance with my compact Excavator. I have gone through about the entire electrical system trying to find the issue. The symptoms began as intermittent starting. Then the glow plugs and engine stopped turning over. Then I lost all ignition and instrument power completely. Things I have replaced that have not solved the problem: Starter, Fuel Solenoid, Fuel Solenoid Harness, Fuse Box, Fuses, Relays, Ignition switch, arm rest sensor. The only things I have not ruled out is a bad ground or the alternator. The biggest clue I have is this: I have voltage at the ignition, I also have continuity from ignition to the fuel solenoid. The fuel solenoid is confirmed to function, but when I turn the ignition on, the fuel solenoid does not energize like it normally does. Testing the voltage at the ignition, I am getting 12v on all 3 poles on the ignition switch with it turned off. When I turn the ignition on, my voltage drops to 0v on all 3 poles and from the ignition power itself. I confirmed the ignition is wired correctly and functioning properly as a switch.

 

[Makar]

Any service manual for bobcat
samarskiy.psn@gmail.com

 

[Vetech63]

Sounds like you have a corroded or bad connection at either the positive or ground. Check your battery connections at both ends first. Make sure they are clean and tight.

 

[Daniel.]

Sounds like you have a corroded or bad connection at either the positive or ground. Check your battery connections at both ends first. Make sure they are clean and tight.

I apologize I forgot to include, I also replaced the Main Positive cable, the battery, and the battery connectors. The main Positive line going to the Starter was slightly damaged because of someone who was using the machine, they left the fuel solenoid engaged for way too long, causing it to actually melt the insulation of this main positive cable. I have tested voltage to the starter after the fact, which is where all the positive leads branch off from, and it is at full voltage still making me believe the cable and connectors are not the problem. I located all the negative connections, but they are all in one location under the entire crane assembly and they are tapped into the metal base itself, which seems to me to be impossible to access without lifting off the entire crane. I did get down there with my hand and feel around. I could not feel or see any rust or loose connections. I also spread over the negative taps a liberal amount of antioxidant compound for safe measure. Another update from yesterday is, very rarely, I can get the engine to turn over for about 3 turns, then it quits out and nothing works, including any of the electrical. I tell ya this thing is a soab.

 

[Daniel.]

Any service manual for bobcat
samarskiy.psn@gmail.com

I do have an operation and maintenance manual for this bobcat, but I do not have the "service manual", which probably would have electrical schematics.

 

[007]

The information you have posted is a huge clue as to what the problem is.
Your tests of the ignition switch are with respect to what??
Where are you placing the negative lead of your meter.
What you are reading is not possible with out some huge earthing issues.
To read three high and three low readings at the ignition switch shows the system has not got a earth reference.
It might be faster to locate the issue by attaching one of your meter leads to the negative terminal of the battery and start measuring for a raised potential on body and engine block and so forth.
If the engine stops cranking sometimes would suggest an earth strap of some kind that is just touching.

 

[Daniel.]

The information you have posted is a huge clue as to what the problem is.
Your tests of the ignition switch are with respect to what??
Where are you placing the negative lead of your meter.
What you are reading is not possible with out some huge earthing issues.
To read three high and three low readings at the ignition switch shows the system has not got a earth reference.
It might be faster to locate the issue by attaching one of your meter leads to the negative terminal of the battery and start measuring for a raised potential on body and engine block and so forth.
If the engine stops cranking sometimes would suggest an earth strap of some kind that is just touching.

Hello, I am not sure how to edit my post otherwise I would have changed my statement about the ignition poles. I am getting 12v from my ignition power to each pole. In other words, when I put positive to my power at the ignition, and negative at any of the 3 poles, it is giving me 12v, so I am somehow getting a ground from my ignition poles. I am not an expert at DC electric but this doesn't seem correct to me.

 

[007]

Its a little confusing the way you are describing it but it sounds like you are measuring across the terminals of your ign switch.
You cannot do that as you will appear to get a ground when measuring like that.
All of your measurements must be made with respect to some good ground point in the system.
Therefore you are tracing the path of the positive potential through the system with your tests.
When the switch is in the off position the circuits it would normally energize in the on position with have a good path to ground as far as your meter is concerned.
If you just posted something there is a little icon appear which will allow you to go back and edit something you have posted.
Regards

 

[Daniel.]

Its a little confusing the way you are describing it but it sounds like you are measuring across the terminals of your ign switch.
You cannot do that as you will appear to get a ground when measuring like that.
All of your measurements must be made with respect to some good ground point in the system.
Therefore you are tracing the path of the positive potential through the system with your tests.
When the switch is in the off position the circuits it would normally energize in the on position with have a good path to ground as far as your meter is concerned.
If you just posted something there is a little icon appear which will allow you to go back and edit something you have posted.
Regards

Hello, thanks for the clarification. Yes that is what I was doing and realised it was not giving accurate reading. Yet, what I have not ruled out as an possible cause is perhaps a poor ground connection, as stated earlier in the thread. All of the negative connections for the circuits are tapped into the bottom of the crane near where it mates with the rolling tracks. I have tested all circuits and am not losing any voltage. The main positive line from the battery was melted slightly from improper operation but other than the insulation, the wire seems fine.