Bobcat 753 Traction lock problem

[marvschuh]

Bypass solenoid

Atcoequip Thanks for the reply. I needed to move the bobcat so I unhooked the 3 wire connector. Measured the ohms and it is right at specs - .5 for the pull and 11.0 for the hold. Once I put 12 volts to the hold coil it only takes a micro second to momentarily energize the pull side. It worked just fine for getting it on the trailer. Hooked everything back up and when I turn on the key the solenoid energizes and holds but releases about 5 - 10 seconds after the engine starts. I'm now wondering if maybe my seat sensor is playing tricks seeing as the traction lock is hooked only to the BICS part of the system and so is the seat. Marv

 

[willie59]

Good question Marv, don't know the answer myself, not real familiar with the 753. Does it have a code readout display? Or, just BICS LED display beside and behind seat?

 

[marvschuh]

The only code I get is the 3 flashes on the BICS traction indicating the hold coil circuit shorted to ground. I have the wiring schematic which is very simple. sure would like the schematic for inside the BICS. thanks again for your reply Marv

 

[willie59]

Just an old guess, but if your 753 is anything like the old 743, I've seen the seat sensor transducer crap out many times and affect the brake solenoid system. Never have know how to bypass the seat sensor, it has three wires as well. Have replaced the transducer on the seat sensor on 743's several times and fixed the problem. Can't say for sure that's your problem though.

 

[Cannon]

3 Traction Lock TS Ideas

1. Fuze Box. When you remove the correct fuze you'll see (or at least hear) the circuit engage/disengage.

2. Seat Sensor. Lift Cab, under right butt cheek.

3. Seat Bar Sensor. Male/female coupling may have come loose inside the left side of cab.

The coupling stopped me in the midst of a 360 degree turn 1/2 way in/out of a 55mph two lane highway. Had guys running 200yards down the road warning on comming traffic. While I jumped out, and checked the above in that order, took :10min (probably more since I was glancing up every 20 seconds waiting to get creamed) Sure wished I did the check in reverse!!

 

[bremery]

I know this thread is a little old, but I figured I would share my experiance on a similar issue. I have a 1998 763 that was giving me intermitent traction lock problems. I would get six flashes on the BICS when I pushed the traction lock override button and could not move the machine.

My manual said the pull circuit had shorted to ground. I checked all the wiring and found the pink/ white wire going to the brake relay from the BICS had the insulation cut by the wire clamp that is near the 4 wire connector under the cab. This gray connector is right before the wires go under the pump towards the rear of the machine. The ground wire was also cut which was causing the BICS to throw the code. I hope this helps someone.

 

[bspoon3]

My 753 won't start with the key switch, but I can jump the starter and it starts. When It is running the traction override button won't release and the lights don't work.
Anyone have any Ideas? Any advice would help.
Thanks

 

[willie59]

Is your 753 a C, F, or G series bspoon3?

 

[bspoon3]

I just got the machine and don't know if it is a c f or g. Would it say on the serial number?

 

[willie59]

It's easy to distinguish the different model series bspoon3. The C and F series had rectangular headlights on front of cab. The C differed from the F in that it has a 2 piece rear door, orange stamped steel door on bottom with a black stamped steel section at the top bolted to the lower orange section. The F series is when they went with the one piece, stamped steel, orange rear door, but it still had rectangular headlights. The G series has the triangle shaped headlights in front of cab.

 

[bspoon3]

It is a C model. It has the 2 piece door

 

[willie59]

It's hard to say for certain whether your starter, traction lock, and lights not working is related or not. The fact that engine will run indicates there is power to system to operate fuel solenoid, not sure how the other functions are related. I seem to recall the C series had fuses and relays in rear engine compartment, to the right of engine. You might check power in and out of fuses. And the C series goes back a few years, not sure how much ECU controls these components, on the F and G series I know for sure the ECU controls starter and BICS functions, likely does on the C as well. If it does, traction lock won't release until you get all the lights on the BICS controller behind seat. As for starter not working, and you have determined fuses are good, I'd start by testing the key switch for start output voltage. If key switch works proper, start going through the harness to find why start circuit not working. Hope that helps some.

 

[bspoon3]

So I checked the fuses which all looked good and I used The ohm meter. I checked the voltages to the key switch and relays which read 12 volts and still nothing worked.
I went to lunch and when I came back I noticed the lights were on. I jumped in the machine and started it with the key switch. But the green traction buttOn still doesn't work and when I put the lap bar down the lights On the ECM dont come on?
Could it be a short or bad ECM ?
Thank you again for the help

 

[willie59]

Well, I'm just not real sure about the C series, been too long since I've worked on electrical on those. But if they're like the later machines, they have an ECU that controls pretty much all functions of machine located behind the panel to the left side of your left foot when sitting in cab. The BICS controller is a different component that works in conjunction with the ECU. If I remember correctly, the BICS controller is a small box mounted on rear wall to right of seat when sitting in cab. It requires all the LED lights on BICS to operate before traction lock solenoid releases brake. If the traction lock LED is flashing, that indicates a problem with traction lock circuit. If the other three LEDs come on but traction lock still doesn't light or flash, could be a faulty BICS controller, not sure how to test one myself. One thing about Bobcat skids, they are bad about harness problems, wires being rubbed on various machine components messing up wires.

 

[bspoon3]

Oh ok it's the BCIS box that none of the lights are coming on. Sorry I thought that was the ecu

 

[willie59]

Not sure what to tell you. BICS controllers are fairly reliable, but that doesn't mean yours is good, they just don't mess up often. Wiring problems are more typical, it could be your BICS controller is just not getting power. I don't know enough about the 753C to know what to check on the wiring. Maybe try to contact your local Bobcat dealer and ask them if they can test the BICS controller and provide you with a wiring schematic for your machine.

 

[bspoon3]

Do you know Anything about the switch under the seat?
I lifted the cab and it looks like there is a switch under there that has come apart. How does that switch work or what is it's function?

 

[willie59]

The seat switch is a magnetic switch that activates when you sit in the seat. If the switch is not activated, the BICS controller won't allow loader operation or parking brake release. It has three wires that go to it, I don't know what the function of each wire is so I don't know how to bypass that switch. Anytime I've worked on them when they are broke I've always replaced components necessary for seat switch to operate properly.

 

[bspoon3]

Thank you for your help I finally solved the problem. It was the broken seat switch and a faulty or weak fuse

 

[willie59]

Awesome!

Thanks for the update bspoon3.