Bobcat seat bar relay

[badranman]

I have a 2003 Bobcat 763 with 160 hrs on it. A couple of weeks ago the seat bar relay apparently bit the dust. The machine would drive but the hydraulics wouldn't function. Sometimes it fixed itself, sometimes not. Dealer installed new relay and it worked fine for about 20 more hrs. Tonight the same thing happened. They said this was the first machine they seen with this problem. Anyone else have this problem? Kinda sounds like a short or something. :beatsme

[Steve Frazier]

Has the relay been bench tested to show it has actually failed?

If not, it could be that an intermittent problem exists with one of the inputs to the relay in the form of a broken wire or dirty/loose contact.

I can't remember ever having a relay fail in any application, it seems strange that 2 should fail in the same location.

[badranman]

First, let me clarify the problem as I wasn't running the machine when the problem started. While driving down the street the machine stopped solid and nothing would work, no steering, no hydraulics. Push the traction lock overide button and you could steer it. Forward to last night. Same thing happened. This was after the "fix". Anyway, sure enough the mechanic meets me at the shed and the Bobcat works perfect. He replaces the BICS sensor saying the plastic nut holding it down comes loose once in awhile and moisture may get in. Machine runs fine (it did anyway). I drive it around and use it for about 10 minutes with no problem. He loads up his tools while I start the Bobcat to put it back in the shed and it isn't working again! He messes with it for another 10 minutes checking all the wiring and says he's stumped. He is the best mechanic at the dealer so I've been told. Anyway he say's he want's to go back to the shop and have a look at some more manuals and talk it over with a few guys. He also wanted to see if something was heating up and causing the machine to operate after a cool down period like it seemed to do in the morning. That's where I stand right now. We will try again tomorrow afternoon. Still :beatsme

[badranman]

Just posting an update on the problem. The dealer found a short in the wiring harness. That explained the on again / off again problem. So far so good. Thanks.

[gljs1094]

badranman, i have the same problem with my bobcat 463. could you tell more about the short in the harness? where in the harness? how did they discover the short? thanks.

[badranman]

Man, you sure are blowing the dust off this thread, lol. I have no idea where the short was. If they did tell me, I've forgotten it by now. I wish I could help. Next time I'm at the dealer I could ask the shop manager if he remembers.

[gljs1094]

Thanks for the quick response. I did not look at the date when i responded to your "dusty" thread. I just did a search on yahoo and it brought up the forum. Let me know what you find out. Thanks again.

[special tool]

Thanks for the quick response. I did not look at the date when i responded to your "dusty" thread. I just did a search on yahoo and it brought up the forum. Let me know what you find out. Thanks again.

I have a 463.
Look up to the left over your head after you put the bar down.
The bar chaffs the harness here.
Check this first.

[AtlasRob]

A similar problem came up in the past week or so. I dont run Bobcats so bare with me. I will search the threads in a minute and update this.
I believe the reply was to tilt the cab and check the wiring loom wherever it is cable tied. It seems that vibration causes a breakdown of the loom.

check this.
http://www.heavyequipmentforums.com/Forum/showthread.php?t=10463

[gljs1094]

special tool - Sounds like a good starting place. Thanks.

If I don't see anything there, i will start at the fuse and chase the wiring through the relay, all the way to the solenoid. I will also look at the BICS circuitry too.

Does anyone have a schematic?

[AtlasRob]

It might be worth you checking out this one also.

http://www.heavyequipmentforums.com/Forum/showthread.php?t=9801

[special tool]

special tool - Sounds like a good starting place. Thanks.

If I don't see anything there, i will start at the fuse and chase the wiring through the relay, all the way to the solenoid. I will also look at the BICS circuitry too.

Does anyone have a schematic?

I have the factory service manual.
I can scan and post any diagram you need as long as my 3 year old daughter isn't busting my chops.;)
Let me see if it has bics in it...

[gljs1094]

Thanks atlasrob.

so you know,the traction lock light on the BICS flashes 3 times when the brakes lock up. The manual states this is a short to ground - which is consistent with everyone's chaffed wire theory.

I'll check all of the suggested ROPS locations and wire tie locations and post my findings.

It appears I will have to cut the mesh cover over the wiring harness to check the entire deal.

[gljs1094]

thanks tool.

i can relate to the 3 year old ... i have a 16 year old that is running around here acting like a 3 year old! It takes forever to read and reply because he is so spastic. I cannot wait for his meds to kick in!!!!

[special tool]

Thanks atlasrob.

so you know,the traction lock light on the BICS flashes 3 times when the brakes lock up. The manual states this is a short to ground - which is consistent with everyone's chaffed wire theory.

I'll check all of the suggested ROPS locations and wire tie locations and post my findings.

It appears I will have to cut the mesh cover over the wiring harness to check the entire deal.

Do you have the service manual, or the operator's manual?
If you have the service, then you have the same diagrams that I do.

[gljs1094]

i have the operator's manual only.
i've been looking on ebay to buy the service manual.

[special tool]

Okay.
I have all the diagrams, but they are a pull-out, and won't fit in the scanner, of course:rolleyes: - I don't know why they did that.

Traction lock overide switch goes to pin# 22 and 12 on bics controller

Seat bar sensor goes to pin# 15, 10 and 20 on bics controller

Brake switch goes to pin# 23 and 4 on bics

Hydraulic lock solenoid supplies a ground only to bics at pin#1....(maybe
check chassis ground continuity here? oxidation????)

Traction lock solenoid takes 12v (low)from pin# 3 (if happy) and sends it to the traction lock for a relay signal which opens through a 25a fuse from battery.

[gljs1094]

thanks for posting the wiring schematic info. i was not able to get to the garage today. it will likely be next weekend before i get back to troubleshooting the loader.

[injens]

I have/am having the same sorta problem with my 763. A couple months ago I tried to get the machine going but the status LED wouldn't light up when the lap bar was down. I have a service manual, but my machine sits outdoors, and the temperature was about -40...too cold to fuss with mechanics. So I hauled it to the service/dealer, where it sat in their heated garage for a week-end before they got to it. The "problem" had disappeared, but they still inspected harness, etc. and found nothing. We figgered it might have been due to the rather chilly weather. But yesterday same thing happened and it was a balmy 30 degrees. So, it ain't the cold, because it has worked fine for the past 6 weeks in weather around 15-20 degrees. Like the rest of you, I'm stumped.

[BruceJ]

Not in to dusting as some!!! My 863 does same thing intermittently. Upon scientific analysis, it only does it when the BC parked and shut down on some kinda incline(not every incline every time), then upon restart she snags.Maybe mine is a relay/switch issue because i can usually get her back on track with a few raising/lowering of the seat bar....

[Rayhat]

Pretty much the same problem on a 863 C. I'm going to try all these ideas and at least chase down the wires.

[mrfixitpaul]

A few things to check on BICS troubles...are the bolts tight where the seatbar pivots(can cause sensor to not see it is down) If brake doesn't release intermittent but all bics lights are on check the 1/4 inch bolt on the brake plunger...they can get grooves and hang up. also make sure to check for trash under or behind seat that will affect the seat sensor if it is old enough to have one

[AtlasRob]

A few things to check on BICS troubles...are the bolts tight where the seatbar pivots(can cause sensor to not see it is down) If brake doesn't release intermittent but all bics lights are on check the 1/4 inch bolt on the brake plunger...they can get grooves and hang up. also make sure to check for trash under or behind seat that will affect the seat sensor if it is old enough to have one

:notworthy Very good info, :drinkup and welcome aboard ( I see that is your first post, I hope you have more as good as that ) :D

[BruceJ]

Yep, checked all those. Will keep u posted if she fixed or not....

[redneckpete]

These problems are not relay related.

On the left hand side of the seat bar pivot point is a magnetic switch. It is incorporated into the pivot mechanism. This senses the position of the seat bar and opens and closes a switch using a magnetic switch.

These switches run off a white plastic bushing with a brass insert and a magnet moulded into the plastic. They strip, wear out or otherwise move out of alignment.

If your machine is almost new you may be able to remove the bolt and replace only the bushing. More likely you will need to cut off the nut (because the bolt will spin inside the bushing) and replace everything but the black switch mechanism itself. You can test the black switch part by watching the lights on your BICS controller (machine turned on not started) while slowly rotating the white bushing inside the black switch. When the magnet gets to a certain point the switch will close, and the BICS controller will indicate the seat bar is down. You dealer will stock the parts, they go all the time.

I know for fact in the smaller machines (463 or S70) you can replace the switch without removing the bar from the machine, although you do need to disconnect the one side. I'm not sure on the bigger machines.

Pete

[BruceJ]

Hey redneckpete,
Thanks for that. Got her up on blocks at present so cannot check, but, if i disconnect the plug to that mag switch will it show up "error" on board or will it default to shut or open switch?????

[crutch]

Have you checked that the BICS solenoid valve on top of the BICS valve is working correctly? (not the spool lock solenoids, but you could check them too)

When energized this valve supplies pilot pressure to the lock valves in the BICS valve which then open the oil paths to the Lift/Tilt cylinders. It has a screen on it which likes to collect metal filings, due to magnetism from the solenoid.

[BruceJ]

Have you checked that the BICS solenoid valve on top of the BICS valve is working correctly? (not the spool lock solenoids, but you could check them too)

When energized this valve supplies pilot pressure to the lock valves in the BICS valve which then open the oil paths to the Lift/Tilt cylinders. It has a screen on it which likes to collect metal filings, due to magnetism from the solenoid.

Can you explain where the sol valve is(Bics valve)???
Bruce

[crutch]

The BICS valve is a casting that sits on top of the DCV. This is where the lines going to and from your cylinders hook up. It is used because the spool lock solenoids are not reliable/safe enough on their own. Here it is:

http://i50.photobucket.com/albums/f339/soylent_orange/BICS.jpg

Anybody looking for summer interns? ;)

[redneckpete]

I'd be unbelievably surprised if that was his problem. The magnetic switches on the seat bar are KNOWN to be flaky and unreliable. The BICS system is all electric over hydraulic, the hydraulic side of which is highly reliable, and the electric side of which is pretty reliable.

I'm off to a meeting tonight. I'll check tomorrow and pull out the manual for the troubleshooting procedure, but trust me, start with the seat bar switch.

Pete

[BruceJ]

Good stuff guys!!!!!

[rob shirkowski]

I am having the same problen with my seat bar sensor. I have taken it apart several times even used hose clamps to keep the magnet and sensor together so that I can operate the machine. only to find the very next day again, nothing works! The machine is a 2000 753 with hand controls. I am wondering if there is a way to by-pass the magnet and just hard wire the sensor? The machine does not have a seat sensor only the seat bar sensor> Thanks for any help. Rob