863 electrical issue.

[ReTonkulousgarage]

I am building a house. A friends dad gave me an 863 to use for the duration of the build. He had loaned to an abuser for a couple of years. Zero maintenance. It is free for me to use, but I have been fixing many issues. I have more hours working on it than using it. Now I need to get the pad done sooner than planned, so I will rent a dozer to finish it. But I am not the guy who gives a borrowed tool back not working.

SN 514414477 1995 year? Manual foot controls. "NO JOY STICKS" Local Bobcat does not want to touch it.

I have service and parts manuals.

8 hoses replaced.
3 cylinders rebuilt.
Fuel tank pickup converted to steel. (required removal of the power unit on this model.)
Hour meter fixed.
Fuel gauge fixed.
Temp gauge fixed.
New seat.
All BICS sensors cleaned and checked.
New tires.

I have 100 hours on it since picking it up.

The new issue is the interlock will randomly engage. I can not replicate by doing a specified function. Scooping, dumping, traveling in both directions, happens with any of them. It has been getting worse as I work through the issue. Now it locks within 5 minutes of starting the unit.

Control panel shows traction failed. 3 flashing lights. "Coil circuit shorted to ground".

Done so far. Checked the traction solenoid for correct operation. Was OK. Checked power to the solenoid and the ground. OK.
Replaced solenoid. No change.

Pulled all of the harness apart that I could access. Checked all of the plugs. Continuity tested all BICS wires end to end and to ground. They all check OK. I have checked all of the plug pins, cleaned and made sure contact is happening. Cleaned the fuse holder and contacts. Switched the brake relay with the starter relay. No change.

I pulled the traction solenoid and clamped the lock pin up. Bolted the solenoid to the side with one bolt. I can travel freely, but the failure light will come on as I watch it.

While using the unit locked out, it worked fine for about 30 minutes. Then the control valve failed and boom/tilt locked. Shows 3 blinking lights also. "Valve output circuit shorted to battery voltage".

Looking for advise.

 

[ReTonkulousgarage]

I received this from a member here.

On that era 863, those "coil shorted" / "output shorted to batt" codes almost always end up being wiring, not the coils. Since it gets worse as you run it, I'd do a hard wiggle test with the machine running and a test light or meter clipped right at the traction coil connector, then follow the harness back under the cab, around the pump stack, and up behind the seat bar. You want to see if vibration makes the feed or ground drop out or spike.

Also check main grounds from engine to frame and the BICS module ground, plus battery/alt voltage under load. Low or spiking voltage will make those BICS boxes throw ghost short codes. Seen that on a couple 773s. Any green crust or stiff spots in that harness are suspects.

Last time I chased one of these I used the parts manual diagrams from https://machinecatalogic.com/bobcat-863-g-series-skid-steer-loader-parts-manual/ to see harness routing and connector locations.
My response.

Thanks for the info. I have done the wiggle and meter test on everything. I have had the harness exposed except right over the pump. It looked OK when I had the power unit out to fix the fuel tank, but that was 80 run hours ago. The grounds have been cleaned, first thing I did. I have dealt with that on so many classic cars.

I will keep going through the harness based on what you said. I figured it had to be in there somewhere. I find it weird that it is throwing the code on 2 systems. I thought maybe the BICS module might be failing.

I will post up what I find when I find it.

Thanks.

 

[ReTonkulousgarage]

Spent 3 hours on it today. Going through he harness again. Cleaned the connectors that do not plug into anything. Thinking maybe they could be the issue.

Set it on jack stands. Pulled the wheels and tires. Ran it for an hour while shaking wires. Nothing. During this time, I loaded the seat with a 60 pound bag of concrete and lowered the seat bar. Stood in front and ran the motion controls for 30 minutes. (boring) No issues. Lifted the cage and strapped the controls forward. Shook wires for 30 minutes. No issues. Put it all back together, thinking, maybe cleaning those non used connections fixed it. (doubtful.) Moved 2 loads of dirt and, BAM.

It will not reset without turning the ignition off. Raising and lowering the seat bar will not reset it. Now it will instantly lock when I press the interlock override button. Goes click, click.

A little background on me. I wire classic cars, hot rods and the like. Wiring is not new to me. But this has me frustrated.

 

[mrbb]

is there seat safety pressure switch?

if so, maybe that is causing the issue

as when pressure gets lifted from YOU moving in seat while working machine, it might just be enough to trigger things

as it ran fine while you had a stationary weight on it, but once your actually driving operating it, again you can be shifting weight and switch triggering , they do wear out over time
and lots of china junk is used to replace them!

food for thought maybe?

 

[ReTonkulousgarage]

I thought of that. The bar spring has been removed so he seat no longer lifts. Basically, it is engaged constantly.

 

[tbirdphil]

Check the charging wire from the alternator to the battery. Mine cracked at the alternator due to engine
vibration. The variation in system voltage drove the controller crazy. Did exactly as you described..

 

[ReTonkulousgarage]

Checked those again and made sure they are clean, again. No issue found.

 

[ReTonkulousgarage]

Driving me up a wall.

I found a note that said high voltage can cause fault issues in the BICS contoller. Checked the alternator output. 15.5 volts and the bearing has been making noise. Ordered a new one. 14.2 volts now. No change.

I bypassed the traction lock wire from the controller to the solenoid with new wire. No change.

The lack of consistency is crazy. It will run for an hour one time. Then will release and reset instantly others. And everything in-between.

I am leaning towards the controller being the issue. $750. If I could figure out a way to bypass all of the electrical controls I would.

Open the valves to work when the key is on. Put the traction lock on a separate switch system.

Looking at the function of the hydraulic system now. If I can fool it, I will.

 

[larryb346]

You might check the fuse panel and be sure the fuses are for lack of a better word setting in the clips. I had issue on 763 I chased and turned out to be a fuse not making great contact. It would intermittently lose contact enough to set off the bics. One side of the fuse slot had opened up enough to cause the issue. Both legs of fuse checked good with meter but could wiggle fuse and it would cause meter to bounce.