Bobcat 553 Traction lock issues - need help

I am struggling to understand the problem with my traction control.
First - background on the unit. I is a 1999 F series. It has no seat switch. I have owned it 9 years. It has 4600+ hours on it and the motor is still strong and uses no oil.
The engine compartment was a mess when I got it. I cleaned it and found problems in the fuses. Water had gotten in under the cracked fuse cap and corroded a lot of wiring. Several hours of tedious cleaning and sealing, that problem was solved. it is inside when not being used about 95% of the time.
Last year, the unit started having a strange mobility issue. When I would get in and start it, more than half the time when I hit the traction control, the lights on the BICS turned green, but no clunk of the solenoid. From time to time is would lock up in use. Shut off, restart and go back to work - sometimes with a click, other times no click.
Yes - I have already had the brake engagement embarrassment. That us not my problem. Wiring does not appear to have any loose spots or mice chews. Am I dealing with a worn out solenoid? Bad relay? How do I check the three wires to the solenoid. I understand there is a pull and hold coil. Struggling to find the issue as it is intermittent....my favorite kind of problem. Any help would be greatly appreciated.

Well, I don't have any manuals or info on the 553, but if it's similar to the other 53 series machines the traction lock is controlled by the BICS controller. The three wires at the solenoid are pretty much common in how they're used on all machines. When you press the Push to Operate button the BICS controller does two things, 1) it sends power to the Brake relay in the engine compartment to trigger the relay, this allows the relay to send battery power to the white wire (pull coil) on the brake solenoid, and 2) it sends power directly from the BICS controller to the red wire (hold coil) on the solenoid. After a couple of seconds, just long enough for the solenoid to engage, the BICS controller drops the signal to the brake relay to stop sending power to the white wire on the solenoid.

Being an intermittent problem it's not going to be easy finding the source of the problem because it will most likely work every time you try to troubleshoot it. But if it's not engaging when you first push the button, you need to check that the brake relay is working and sending power to the white wire. Again, it's only going to happen for a few seconds. As for the red wire, if all the lights are lit up on the BICS controller then you should see continuous power on the red wire when you push the button.

I had similar issues with a 753G the fuse block was corroded and the fuss were not allowing the flow of current strong enough to pull and hold the solenoid, just try bypassing the fuse block all together with some inline fuses, they will fit behind the block and all pack back in okay. It solved all my problems in one go!! Cheers Justin

If it uses blade fuses, (don't know, never worked on BC's) Try this: take out the fuse, give the blades a 30º twist, with a pair of pliers, and re-insert. Applies a little more pressure to the connections , below the fuse. Sometimes that's all it takes to re-establish connection...

check your battery cables and battery posts.
they need to be clean and shiny.

most intermittent problems are caused by the battery connections.

a common problem in 50 series machines is a bad ground in the main wiring harness.
in the area of the brake solenoid peel back the harness cover and you'll find a splice with 2 or 3 grounds. add another ground wire (or 2) to the splice and run it all the way back to the battery, and also find a clean chassis ground under the cab
most of the time this solves the problem.

Several years ago I did the blade twist because the unit would not start. That cured the main starting problem. I have not had the time to pull the harness convoluted tubing back yet....got bigger problems. Pickup truck broke frame. Used bobcat for 3 hours this morning moving manure and the traction lock did not "click", nor did it engage. I am beginning to wonder if the spring on the lock has not failed and it is not always returning to the locked position. Probably 20 hours of use in the last week and nothing is amiss other than it does not lock.