bobcat 743b-engine wiring picture needed

Hello skidsteerers, I'm new to the forum. I just got a used and dead 743b, hoping to make it go for use around the yard. Spent the last weeks degreased, pressure wash 3 times just be able to see what im doing. A disclaimer: I know nothing about bobcat; just a guy who likes to do thing and learn as I go. anyway, I am looking for a picture of the wiring on the right side of the motor (fuel filter side.) I think the previous owner did some "custom wiring" and all the end wires are white but when I peeled out some protector sheets, I see different color after the wire nuts... Some wires are loose and I can't tell what go where. I bought a manual but the wiring scheme is no use . Specific questions: 1/ toward the end of the engine block, there is A loose wire there. where do that go ? 2/ on the hydraulic filter, there seem to 3 wires, what are they and where do they go? 3/ under the cab, right next to the wire harness, there are 3 connectors/plug (blue/orange , red/white stripe and orange) . do they go some where or they are some type of test connector. I am tracing electrical now because the bobcat drain my battery in 45-60min Ok... you guys can laugh at me: what's an office guy doing with a dead bobcat ? I know, I know... Have a good day, ALL

I don't have any pictures, just the same book that you probably have (which I think has quite good wiring diagrams).
Is the battery charging at all? Does it discharge while sitting, or running or both? First, start by disconnecting the ground at the battery and put the charger on it to give it a full charge. Then, when you touch the negative terminal, there should be a pretty good spark as it has to have a pretty good parasite draw to run a battery down in that time.
You need to find out where the drain is coming from, and the best way is to put an ammeter in series with the battery so that you can start disconnecting things to see where the draw is coming from; it's likely too much draw for the typical DMM, I have a 25 amp panel meter scrounged from a piece of equipment that I use. My first guess would be the alternator / regulator. If you have a parts house that does testing, I'd take it to them and test it while the battery is charging, that could solve it right there.

According to the wiring diagrams, the three connectors you mentioned are:
Lt. Blue / Orange -10ga. to glow plugs (or from glow relay)
Red / White - 12ga. Live fused accessory
Orange - 16ga. Switched fused accessory

flyerdan said:

I don't have any pictures, just the same book that you probably have (which I think has quite good wiring diagrams).
Is the battery charging at all? Does it discharge while sitting, or running or both? First, start by disconnecting the ground at the battery and put the charger on it to give it a full charge. Then, when you touch the negative terminal, there should be a pretty good spark as it has to have a pretty good parasite draw to run a battery down in that time.
You need to find out where the drain is coming from, and the best way is to put an ammeter in series with the battery so that you can start disconnecting things to see where the draw is coming from; it's likely too much draw for the typical DMM, I have a 25 amp panel meter scrounged from a piece of equipment that I use. My first guess would be the alternator / regulator. If you have a parts house that does testing, I'd take it to them and test it while the battery is charging, that could solve it right there.

According to the wiring diagrams, the three connectors you mentioned are:
Lt. Blue / Orange -10ga. to glow plugs (or from glow relay)
Red / White - 12ga. Live fused accessory
Orange - 16ga. Switched fused accessory

Click to expand...

Thank you Flyerdan. I got the the Service Manual for 742B and 743B on a CD. Not sure if it the same manual you have but the wiring diagram is below. Thank you for IDing the 3 wires under the cab. Any idea what the wire on the engine block is/go ?

hungfish said:

Thank you Flyerdan. I got the the Service Manual for 742B and 743B on a CD. Not sure if it the same manual you have but the wiring diagram is below. Thank you for IDing the 3 wires under the cab. Any idea what the wire on the engine block is/go ?

Click to expand...

Mine is for the 741 742 and 743 743DS but I'd imagine that they share a lot of the same wiring colors and layouts to simplify parts stocking. The book number is 6566109.
It looks like the three wires from the hydraulic is the trans charge pressure sensor, which is number 7 on the diagram. It's the only hydraulic connector with three wires so it's a pretty good guess.
As for the single wire along the block, determine the color/trace and gauge, find it on the wire chart and then on the diagram.
Example: let's say the wire is purple with a white trace and 16 ga. The legend tell us that the wire number is 36T, and finding it on the diagram shows that it's for 12 which is the coolant temp sender.

flyerdan said:

Mine is for the 741 742 and 743 743DS but I'd imagine that they share a lot of the same wiring colors and layouts to simplify parts stocking. The book number is 6566109.
It looks like the three wires from the hydraulic is the trans charge pressure sensor, which is number 7 on the diagram. It's the only hydraulic connector with three wires so it's a pretty good guess.
As for the single wire along the block, determine the color/trace and gauge, find it on the wire chart and then on the diagram.
Example: let's say the wire is purple with a white trace and 16 ga. The legend tell us that the wire number is 36T, and finding it on the diagram shows that it's for 12 which is the coolant temp sender.

Click to expand...

Thank you for the tip flyerdan. I manage to get the motor to run but it die after 10-12 min. Found out that the alternator is bad. to the store to get new alternator tomorow.
I am still trying to find out what this wire is and where it go ???


it is at the end of the motor block on the fuel filer side. I am guessing it is a sensor of some type but don't know where it should connect to. Please help...

thankyou.

hungfish said:

Thank you for the tip flyerdan. I manage to get the motor to run but it die after 10-12 min. Found out that the alternator is bad. to the store to get new alternator tomorow.
I am still trying to find out what this wire is and where it go ???


it is at the end of the motor block on the fuel filer side. I am guessing it is a sensor of some type but don't know where it should connect to. Please help...

thankyou.

Click to expand...

That looks like an oil pressure sender, if it's screwed into the block that's likely. If it's in a water jacket it would be a temperature sender.
From the picture, it looks like the wire connector end is still on the sender like the wire broke off just at the crimp under the insulator. If the end has a spongy vinyl insulator and it twists, it will pull off and you can test with an ohmmeter, an oil pressure sender should be 0 ohms to ground.
Look for a wire without an end terminal that is either yellow with a light green trace, or less likely, solid purple. That would be for the oil pressure light.

flyerdan said:

That looks like an oil pressure sender, if it's screwed into the block that's likely. If it's in a water jacket it would be a temperature sender.
From the picture, it looks like the wire connector end is still on the sender like the wire broke off just at the crimp under the insulator. If the end has a spongy vinyl insulator and it twists, it will pull off and you can test with an ohmmeter, an oil pressure sender should be 0 ohms to ground.
Look for a wire without an end terminal that is either yellow with a light green trace, or less likely, solid purple. That would be for the oil pressure light.

Click to expand...

That's the oil pressure sender

Tazza said:

That's the oil pressure sender

Click to expand...

THank you flyerdan and Tazza