Hi Everyone, I have an issue with the brake solenoid on a 2006 Bobcat s175. I have done as much research as I can without purchasing a repair manual and I was hoping I can get some help here. We recently purchased this machine knowing that the brake unit did not work. In addition to the brake issue, the machine creeps forward when started. I know how to correct the creeping and plan to work on it very soon thanks to these forms and people taking time out of there day to post good info. I have spoken to a bobcat repair shop on the braking issue. The repair shop suggested that I check relay, check the wires and if all seemed well go ahead replace the solenoid. What I have done on brake. 1. Checked the relay and fuse box and all looks good. Went ahead and replaced with new relay just in case. 2. Checked all wires that I could see without cutting the insulation. No pinching no rubbing seen. I did notice that the brake control switch was disconnected. So I plugged it in and confirm the light lite up when flipped back in forth. Also, the seat was replaced by the previous owner and the seat looked like it had a plug of some sort but nothing plugged in. Does this machine have wires that run to the seat that send power to the solenoid? if it does what color and if anyone can explain were it is located or has a picture that be great. 3. At this point, I figured to go ahead and replace solenoid just to rule it out. Done. 4. After scratching my ahead I figured lets go ahead and start testing wires with a test light In which I should have done from the beginning. I do not have a ohm meter to test voltage only a light tester. So at the brake solenoid, No power on any connection. I verified with parking brake switch on and off. Then I went to the switch to be sure it was sending power. It all tested good to my knowledge. So know I am stuck and not sure were to go from here. I heard the system has BICS controller? I am not sure on were its located or even how to test it. Is there anything I can do other than stated above. Thank you for taking the time to read this and helping me out. If I have left any additional information please let me know as I am no expert on this. Thanks again.
Also, I forgot to add that no codes are being thrown and no blinking traction light. All operates as it should. Thanks
Welcome to HEF Bobcatoperator. :drinkup First, the S185 does not use a seat switch, previous owner may have fitted a replacement seat with a switch, but the switch is not used on your machine. First things first, when you start the machine, lower the seat bar, and press the green enable button, do all 4 LED lights come on and stay on with no blinks or beeps?
Hi willie59 thanks for the reply and thanks for clearing up the seat question. I know for sure the seat is for another machine cause its a spring loaded and and looks way too new. As for the starting, lowering bar and pushing button, all lights come on and stay on with no beeps.
And no blinking.
Ok, just wanted to verify that info before we proceed. Bobcat has been using the BICS system for many years, it stands for Bobcat Interlock Control System. Early models, like the 743, have a very simple system, sort of like OBDI on vehicles. The system advanced to the system that is used on later and current models which are controlled by and ECM, more like the OBDII system on vehicles. The parking brake (solenoid that you're have problem with), is controlled by the ECM. Once you drop the seat bar, and that LED lights up, a voltage signal is sent to the ECM to inform it that the operator is in safe position with bar down. Then when you press the enable button, that button informs the ECM that the operator is ready to use machine. ECM confirms seat bar is down and then does two things, 1) it sends voltage to the parking brake solenoid to release and 2) it sends voltage signal to the lock solenoids at the hydraulic control valve to unlock the control valve. A fault with these components, brake solenoid, control valve lock solenoids, or related wiring, will typically be sensed by the ECM and it will send a code, generally with a few beeps to alert of faults. Having said that, next question, when you push green enable button, all LED's are lit, can you operate the loader functions?
When I push the green enable button I can operate the loader functions (drive it and all bucket functions). Also, I forgot to mention that when I first get in the machine, start it with the bar up, I can drive it with bar up but can not operate the bucket and lift. When I pull bar down and hit enable button , I can then use all bucket functions at that time. The safety bar light does go on and off as it should on display.
The thread title indicates no power to the parking brake solenoid. With no power to solenoid you shouldn't be able to drive the machine, sounds like someone has removed the guts of the parking brake inside the chain case. From the things you've described, the ECM is getting proper inputs and is operating properly for other BICS solenoids. This narrows the problem to faulty ECM not sending signal to parking brake relay and parking brake solenoid, problem with the parking brake relay, problem with wiring between ECM, relay, and solenoid, or problem with parking brake solenoid itself. Sounds like you need to look into your parking brake mechanism and see if some parts are missing, get it in order, and install a new solenoid so we can check out the system operation.
How do you check the guts inside the chain case to see if something is missing or disabled? I did replace the parking brake solenoid and relay already. When I replaced the solenoid, I changed the bar that goes down in the chain case. While doing this, I pushed it down and it locked the chain case up. I then pulled it up, added the spring and installed the brake solenoid. The only reason I know there is no power to solenoid is that I put a test light to confirm power and it never showed power. I guess I will try to check wires again and see if I find any exposure and or breaks. Kinda of a dumb question as I am new to the unit, is the ECM located in the control panel with all the lights and gauges or is there a separate ECM that I can test? Hey thanks again willie59 for all your help.
Ok, I'm perplexed. The locking plate is in the guide inside the top cover of chain case, you can push it down and it locks the drive (indicates the park lock disks are on the drive sprocket shafts). You fitted the spring, then installed the solenoid. The problem I'm having, if all these parts are in place, with no power to the solenoid, you would not be able to drive, it takes power for the solenoid to pull that plate off of the lock disks in order for it to drive. The ECM is located behind the panel to the left of your left foot pedal (as you are sitting in the seat). I know of no way for a person to test all the functions of the ECM, maybe Bobcat can, I just don't know. The way that parking brake works (if all things are proper), it has three wires, black, red, and white at the solenoid. The black wire is ground, and you should test it to make sure it does go to ground. The other two wires are power wires controlled by the ECM. When you drop the seat bar and push the green enable button, the ECM sends a voltage signal directly to the brake solenoid on the red wire. But that wire goes to the "hold" coil inside of the solenoid. The hold coil doesn't have enough magnetic energy to "pull" the solenoid spool in. That's where the white wire comes into play. That wire goes to the "pull" coil inside of the solenoid to pull the spool in. But that coil can't take power on it for more than a few seconds or it will burn up the coil. To do this the ECM sends a voltage signal to the brake relay, engages the relay, and the relay sends power to the white wire "pull coil" of the solenoid. After a few seconds, time enough to engage the solenoid, the ECM takes power away from the brake relay, power on white wire goes away, solenoid is engaged and being held in by power on the red wire and ground on the black wire. I can't say for certain, but it's possible you may not see power on the red wire by testing it while plug connection to solenoid is disconnected. The ECM may be seeing this as an "open circuit" and cut power to it. As for the white wire, even if you did see power on it by an output of the ECM to brake relay, it would only be for a few seconds.
OK, now I think I know what's going on. When we took the old solenoid out it had a bar, rod, spring and O-ring. The O-ring was placed at the bottom of the spring closest to the case were it screws in probably from the previous owners. I thought this was correct and the spring slid into the solenoid so that's how I put it back together. It explains why the unit is not locked and I was thinking the opposite of what you stated above. I thought that when it locks, the solenoid pushes the rod in and holds it in place until you unlock it and it just released up. As stated in your response above, I now believe that the wires would not have power if the solenoid was disconnected as the ECM would shut it down to prevent burn up. I will change the order of the brake internals tomorrow and retest. Hey thanks again for the info.
I was wondering how you made out with you brake issue.