Hi there guys, never posted before, great resource you have here, much appreciated. I hope to assist others from time to time. Was a plant mechanic years ago....... Anyway I am having dramas hoping somebody can help. 751c no loader hydraulics bics flashes short to ground (no short to ground still flashes when solenoid disconnected), gone through everyone else's similar problem but cannot resolve mine. Replaced bics solenoid, tested all relays, replaced all fuses and checked contacts, checked every connection wiring and earths. The machine used to stop loader action (bics light out) if it were used for a while and the seat bar was lifted, after cooling down it would work again until you lifted the bar - cause improper resistance in coil - replaced. Found blown aux fuse and oil light would be dim when running - short to ground behind cab gauges - fixed. One thing I have noticed is a slight short to ground (dull test lamp and won't blow fuse) on the boss fuse but after following the schematic and following the wires the ign side goes to the gauge then senders which are supposed to go to ground and if I disconnect any one of the gauges the short goes away. The only area I am think might have something to do with this is the hyd charge pressure sender. It started leaking the same time as the bics said short to ground. I pulled it off and put a blanking plug in its place so oil doesn't go everywhere. I read that some machines (newer I think) need charge pressure of about 58 ohms to allow hydraulic function - hoping it could be this simple but not holding my breath. I also still wonder why the machine is saying short to ground. If it were related to charge pressure the light would be out until the pressure were achieved (I expect). I went into the dealer and he started talking about the controller which he referred to as the ECU of the machine, I worked out he meant the aux hyd controller. Not sure it's related. BTW the diode was blown in the loom before the controller but with or without it even connected the bics light stil flashes........ Please help - thanks in advance Rob
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Hi guys I have an update, now I know it's a bad idea to modify the bics system but; I have picked up 12v from the fused side of the accessories, fed it to the bics hyd lock solenoid via a relay that is switched by the brake hold power. The machine works fine, if i put the brake on no hyd. lift the bar no hyd, get out of the seat no hyd, and when the bar is up the pedals are mechanically locked also. How can this be unsafe, if and of the electrics fail no hyd.... Interested in you thoughts. Also the bics system supplies 8~9 volts but the solenoid is rated to 12v anyway so I cannot see a problem feeding it 12v.
Do you still have the seat switch in your machine, Bobcat updated this system, you need to buy the update kit, it will come with a new display controller. Also those seat bar switches are touchy, make sure none of the plastic parts are broken, the magnets must line up properly.Do not put 12 volts to the spool locks, they are desigened for 8 volts only.Hi guys I have an update, now I know it's a bad idea to modify the bics system but; I have picked up 12v from the fused side of the accessories, fed it to the bics hyd lock solenoid via a relay that is switched by the brake hold power. The machine works fine, if i put the brake on no hyd. lift the bar no hyd, get out of the seat no hyd, and when the bar is up the pedals are mechanically locked also. How can this be unsafe, if and of the electrics fail no hyd.... Interested in you thoughts. Also the bics system supplies 8~9 volts but the solenoid is rated to 12v anyway so I cannot see a problem feeding it 12v.
Also, your machine has codes, you need to get the service manual and read the flashes on that controller behind your right arm. Does that controller still have the picture of the seat on it? If it does, you need to update.Do you still have the seat switch in your machine, Bobcat updated this system, you need to buy the update kit, it will come with a new display controller. Also those seat bar switches are touchy, make sure none of the plastic parts are broken, the magnets must line up properly.Do not put 12 volts to the spool locks, they are desigened for 8 volts only.
What about sending 8v to the solenoid then? It seems like nobody can solve this, I don't understand why I would have to buy an update for an older machine. It has a seat led that indicated that the seat function works fine, get out of seat - light out, sit down - light on. The loader hyd function led flashes 3 times every 3.25 seconds no matter what (solenoid short to ground). I cannot see that it's related to the seat? Am I wrong? Please any advice muchly appreciated.Also, your machine has codes, you need to get the service manual and read the flashes on that controller behind your right arm. Does that controller still have the picture of the seat on it? If it does, you need to update.
Has anyone actually solved this problem, I am at my wits end. If the BICS system is modified to give loader operation when the traction lock is off how can this possibly be dangerous. I understand the risks of a loader that can lift the loader frame with nobody in the seat but in this setup it can't you must be in the seat (seat sensor) and bar down (bar sensor) before the loader hydraulics will work. Can anybody say that this is dangerous..... Really interested in peoples opinions on this. Thanks RobWhat about sending 8v to the solenoid then? It seems like nobody can solve this, I don't understand why I would have to buy an update for an older machine. It has a seat led that indicated that the seat function works fine, get out of seat - light out, sit down - light on. The loader hyd function led flashes 3 times every 3.25 seconds no matter what (solenoid short to ground). I cannot see that it's related to the seat? Am I wrong? Please any advice muchly appreciated.
From my experiences with a 751, they are BICS not BOSS. So its only worried about your safety. It doesn't care what the engine is doing, that's what the gauges and lights are for.Has anyone actually solved this problem, I am at my wits end. If the BICS system is modified to give loader operation when the traction lock is off how can this possibly be dangerous. I understand the risks of a loader that can lift the loader frame with nobody in the seat but in this setup it can't you must be in the seat (seat sensor) and bar down (bar sensor) before the loader hydraulics will work. Can anybody say that this is dangerous..... Really interested in peoples opinions on this. Thanks Rob
It sounds like your BICS box is on the fritz, or there is a wiring issue....
Sadly i can't say what to do, but i see no problem (safety issues though) with hot wiring the lockout solenoid for the lift/tilt lock.
thanks Tazza, it has a boss system as well, I'd love to find the problem as a challenge but 3 or 4 days on the thing is enough. I am still running 12v straight to the bics solenoid, I know the bics system sends 8~9v but the coil winding is rated at 12v can't really see a problem. The mod I have done uses a relay and its all properly done and for the life of me I cannot see a breach of safety. I would never put the bar down with engine running and be out of the seat anyhow, thats the only way I heard of a death by a bobcat with a backhoe attachment.From my experiences with a 751, they are BICS not BOSS. So its only worried about your safety. It doesn't care what the engine is doing, that's what the gauges and lights are for.
It sounds like your BICS box is on the fritz, or there is a wiring issue....
Sadly i can't say what to do, but i see no problem (safety issues though) with hot wiring the lockout solenoid for the lift/tilt lock.
The BOSS systems, especially the early ones i have heard a lot of issues about them. I hope yours turns out to be something simple, when you find the rotten thing.thanks Tazza, it has a boss system as well, I'd love to find the problem as a challenge but 3 or 4 days on the thing is enough. I am still running 12v straight to the bics solenoid, I know the bics system sends 8~9v but the coil winding is rated at 12v can't really see a problem. The mod I have done uses a relay and its all properly done and for the life of me I cannot see a breach of safety. I would never put the bar down with engine running and be out of the seat anyhow, thats the only way I heard of a death by a bobcat with a backhoe attachment.
Chaz, I have a 751 with the identical problem as you were having in this thread. I have a service manual and assume you were using one at the time of this post. My unit has a four light BICS system behind my right shoulder and the locked up problem has been intermittent for the past few months. We found 8 to 8.5 volts to the safety bar as you did and I see that is normal fir these units but your fix seems to be what I need to do. Can you tell me what you are calling the BICS hydraulic lock solenoid? My manual shows the BICS Valve with a solenoid about center on it in figure 20-40-15. PS I must have the older 751 before they installed the smart system with the flashing alerts. Like I said it has a simple four light system to interlock.Hi guys I have an update, now I know it's a bad idea to modify the bics system but; I have picked up 12v from the fused side of the accessories, fed it to the bics hyd lock solenoid via a relay that is switched by the brake hold power. The machine works fine, if i put the brake on no hyd. lift the bar no hyd, get out of the seat no hyd, and when the bar is up the pedals are mechanically locked also. How can this be unsafe, if and of the electrics fail no hyd.... Interested in you thoughts. Also the bics system supplies 8~9 volts but the solenoid is rated to 12v anyway so I cannot see a problem feeding it 12v.
There are lots of cases on the internet with the exact same problem, but for life of me I cannot find one person who has actually fixed it. I have noticed in that last few days that the seat light is staying on, and more than one of the wires from the sensor going back to the bics controller goes to ground, interesting......The BOSS systems, especially the early ones i have heard a lot of issues about them. I hope yours turns out to be something simple, when you find the rotten thing.
