LS185b Hydraulic Brake Engaging Randomly

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Jelcoat

Member
Joined
Jan 20, 2023
Messages
6
Hello, I am a new member of this forum and hope someone can help me fix this problem.
I have a 2006 LS185b with 2000+- hrs on it. I have had the machine for over 10 years. I have put about 1200 of the 2000 hours on it during my ownership. I do most of the maintenance and repairs myself.
Approximately 500 hrs ago the hydraulic brake engaged randomly and made a quick squeal sound. The machine came to an ubrupt stop. The engine continued to run. The bucket tilt and lift continued working. There were no warning lights lit up on the dash. I disengaged the seat belt and the corroisponding light and the brake dash lights came on. I then reengaged the seatbelt which turned off the seatbelt light. I pushed the brake release button and the brake light turned off. The machine functioned properly and did so except for this problem reoccuring randomly, a total of 3 or 4 times over the next 500 hours.
It happened again several weeks ago when I was plowing snow and it has been occuring more and more frequently to the point where I am sometimes limited to only a few feet of travel before it acts up and I will have to preform the reset procedure multiple times in order to limp the machine back in the warm shop to work on it.
I should mention that the Hi setting of the two speed transmission stopped working at some point during the past two weeks as well. I thought that it might be the coil on the 2 speed hydraulic valve that could have been the cause of the problem. At that point seeing as I had the seat assembly removed and the belly panels removed I purchased and installed the following items: 1. Seat belt wiring harness, 2. Seat presence switch, 3. Two speed hydraulic coil and 4. Parking brake hydraulic coil.
Changing out these parts did not fix the 2 speed or brake problem. At this point all I can think of to do next is to either change the diode(s), or remove and inspect the hydraulic 2 speed and brake valve assemblies or possibly replace the pricy EIC.
I am now getting pretty frustrated and feel that I might be overlooking somerthing.
Any suggestions would be appreciated.
Thanks,
Jelcoat
 

Shanmar

Active member
Joined
Aug 27, 2022
Messages
26
My experience would say that the two problems are likely unrelated. I've run into the random brake thing before. The EIC needs to see a steady signal from the seat presence switch and the seat belt switch. Here are some things I've seen cause it on my machine with over 6000 hours on it.
- bad seat belt switch (maybe you can operate it and jiggle it and see if you can make it happen)
- bad condition of plastic/plate in seat not pushing on seat switch reliably
- bad connection of fuses or relays in holders. I've had to wire in replacement sockets for both. I think the ones in the engine bay are the ones in play here. We have been able to have the machine running with someone in the seat ready to operate and wiggle the fuses and relays to figure out which one. The seat belt light would come on.
- bad wire somewhere
- I really doubt the EIC or brake valve is the problem.

For the 2 speed, bad switch in handle is most common. Have had a frayed/broken wire under the seat too.

Good luck.
 
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Jelcoat

Member
Joined
Jan 20, 2023
Messages
6
Shanmar,
Let me start by saying a big thanks for the response.
As I said in my original post I replaced the seatbelt pressure switch and wiring harness what I left out is that I also replaced the seat cushion portion of the spring loaded seat because it had a big rip in it and I was tired of my wife asking me how I kept getting glue on the seat of my pants. The glue was from duct tape.
I currently don’t have anyone to sit in the seat so I can wiggle the wires. I was thinking that it might be possible to temporarily install a 12 volt light bulb in the seat belt harness so I could monitor the consistency of the power while I operate the machine. I’m uncertain which color wire in the harness I should splice one of the bulb pigtail wires into. There’s 2 red 1 white and 1 tan/yellow wire in the seatbelt harness plug on the firewall back side of the seat assembly.
I was thinking that the other wire should be grounded to the battery. If you have any suggestions I would appreciate it.
Thanks again,
Jim
 

Shanmar

Active member
Joined
Aug 27, 2022
Messages
26
Gorilla tape is a little better than duct tape....and flex tape is even better (but way more expensive)--not that I've ever done it......:)

By seatbelt pressure switch you mean the seat belt lock on the RH side of the seat, correct. Making sure that we're not confusing with the seat pressure switch underneath the seat. Although, I've had both go bad.

You could put something heavy in the seat and hook the seat belt to engage the safeties. I don't think you would even need it running. If you hear a beep and a light flashes you wiggle the right thing.

Or, the light bulb idea could work. Keep in mind it might be a very short moment. I've attached (hopefully it comes thru-pretty large file) the electrical portion of the service manual for an L170. It is similar to my L185 which is very similar to an LS185.B. Anyhow, pages 55-15&16 show the pertinent wires.
Wire 310A-red-power coming from fuse in engine area. (5A I think it's the second one down on RH fuse block in engine area)
310B-red-power to EIC
312C-tan-seat switch signal to EIC
314C-white-seat belt signal to EIC
I would say grounding to the battery would work.
 

Attachments

  • l170 electrical section(1).pdf
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Jelcoat

Member
Joined
Jan 20, 2023
Messages
6
Shanmar,
Wow thanks for the detailed attachment. It'll definately come in handy.
I was refferring to the "seat pressure switch underneath the seat". I havn't inspected or replaced the actual buckle switch on the right side of the seat.
I'll look at thet later today andf let you know what I find. Do you know which of the two "seat" switches the power travels through first?
On a separate note you said you have a LS with 6000 hours on it. I'm surprised and impressed. What model do you have? What year is it?
Have a great weekend!
Thanks again,
Jim
 
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Jelcoat

Member
Joined
Jan 20, 2023
Messages
6
Sorry I just reread your latest response and see that you have a LS180. So it must be a 2005 or earlier. Does it have the 3 cylinder Iveco engine in it like the LS185b?
 

oiu789

Well-known member
Joined
Dec 23, 2017
Messages
45
By pass one at a time with a jumper. Jumper 1 test see if that fixed it. leave that jumper in place jumper the other 1 and see if that fixed it. If not continue tracing. Just do not have it running when you get on or off.
 
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Jelcoat

Member
Joined
Jan 20, 2023
Messages
6
Well I believe I found the problem. I spliced the test light into each wire in the "safety interlock circuit" one at a time in the order that the circuit progressed until I got to the hydraulic brake coil. The light initially worked when I pushed the brake release button on the dash but went out shortly thereafter when the brakes locked up. Because I had just installed a new coil on the brake valve I assumed that the coil was working properly and started running the start sequence with a different accessory fuse removed each time I ran the test until the test light stayed on and the brakes wouldn't lock up. I found the source of the problem on my third try.
Several years ago I installed an aftermarket cab heater. While contemplating where I should run the power for it from I located a pigtale in the area of the cab fuse box. It's a heavy gauge orange wire with a flat blade fuseable link prewired into it that isn't part of the fuse block. It was convenient so I used it. I ran a wire from the pigtale to an aftermarket rocker switch that I installed in a blank slot in the dash panel. I then ran a wire from the switch to a two speed fan controller in the heater. What's interesting is that the interlock circuit only tripped when the heater blower was set to low. I would always set the heat on high when I warmed up the machine in the winter. I would switch it to low after it started getting warm in the cab.
I assume that the blower is going bad and somehow sending a short back through the pigtail that trips the safety interlock circuit locking up the brake.
The good news is that I can still run the heater on high and open a window when it gets too hot inside.
I have searched the internet to see oif I can find out what accessory that O.E.M. stock installed pigtail is there to supply power to. My concern is that it was meant for an accessory that required to be wired into the safety interlock circuit. Do you gave any idea what that pigtail is supposed to provide power too?

Thanks for the help,
Jim
 

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