753H BICS no ground for traction lock???

[Skidder Dave]

753H starts fine and with the carnival bar down I can move the arm and tool mount. But I cannot get the Traction Lock to disengage. (Worked fine yesterday). All 4 BICS diagnostic lights are solid green so it should be good to go. WTH? Rang out the Traction Lock solenoid for both pull and hold ohms (red/white wires to black) and values are within tolerance. Then checked the Traction Lock black ground wire feed to chassis ground - it's open - CRAP. Chased the TL black ground wire though the wire harness and found that it leads to the BICS connector. (So much for the terrible Bobcat schematic drawing.) I rang out the (disconnected) black wire all the way back to the Traction Lock connector with good continuity. So HOW? is the BICS grounded??? I checked mounting bolts to the aluminum? BICS case - good continuity. Wire brushed the BICS mounting bolts and washers and also the contact points with tilt-up chassis and remounted all - no fix. I never have been able to get the BICS cable to "click in" so I have tightly secured it with 2 large tie-wraps. I'm thinking I've lost ground internally in the BICS. A new Melroe BICS is about $340. I'm thinking that I should be able to jump/splice the black ground wire directly to chassis ground (while leaving it connected to the BICS connector) to get my Traction Lock working again and NOT have to shell out $$$ for a new BICS. But I have concerns I might completely fry the BICS (BICS works at 8VDC-ish and NOT 12VDC). Has anyone out there encountered this problem or similar? Would like to hear some input before I try splicing to ground. Any suggestions / criticisms / diagnostics will be appreciated! Thanks!

 

[bobbie-g]

Dave, hate to see your post languish here. I'm not the BICS expert you are looking for, but lemme offer a few ideas. First, a BICS glitch on my 763C: if the carnival bar (love your terminology!) comes down before the seat switch engages, the BICS module will wait 10 to 11 seconds before unlocking traction and arms/bucket solenoids. Go find THAT in some manual.....! I chased what I thought was an intermittent open wire for hours and hours before I stumbled onto that one. Now, more to your issue: First, make sure the foot brake (which is only a switch) is "off". I had trouble with one of my machines, had a flakey switch that would not always turn "off", so I finally got it into the off position and quit using it entirely. Second, try sitting in the machine with the bar down, etc, so the machine should be ready to move (except yours won't release the traction solenoid). Push the traction unlock button (mine's on the left side of the console I think) and see if that helps. Given that the arm/bucket functions unlock fine, it sure seems like it's an issue with the traction lock solenoid or wiring. You probably know you can unbolt the solenoid from the top of the drive gear case, retract it manually, and put a hose clamp around the plunger to hold it up while you move the machine. Of course, when you do that, there's nothing to keep the machine from rolling down the nearest hill and squashing whatever's in it's path. Careful when you disable the safety features. I had to do it to move my machine up to the shop to work on it when I had the defective foot brake switch. Good luck, and please post your progress here so we can all learn. ---Bobbie-G

 

[7LBSSMALLIE]

Dave, hate to see your post languish here. I'm not the BICS expert you are looking for, but lemme offer a few ideas. First, a BICS glitch on my 763C: if the carnival bar (love your terminology!) comes down before the seat switch engages, the BICS module will wait 10 to 11 seconds before unlocking traction and arms/bucket solenoids. Go find THAT in some manual.....! I chased what I thought was an intermittent open wire for hours and hours before I stumbled onto that one. Now, more to your issue: First, make sure the foot brake (which is only a switch) is "off". I had trouble with one of my machines, had a flakey switch that would not always turn "off", so I finally got it into the off position and quit using it entirely. Second, try sitting in the machine with the bar down, etc, so the machine should be ready to move (except yours won't release the traction solenoid). Push the traction unlock button (mine's on the left side of the console I think) and see if that helps. Given that the arm/bucket functions unlock fine, it sure seems like it's an issue with the traction lock solenoid or wiring. You probably know you can unbolt the solenoid from the top of the drive gear case, retract it manually, and put a hose clamp around the plunger to hold it up while you move the machine. Of course, when you do that, there's nothing to keep the machine from rolling down the nearest hill and squashing whatever's in it's path. Careful when you disable the safety features. I had to do it to move my machine up to the shop to work on it when I had the defective foot brake switch. Good luck, and please post your progress here so we can all learn. ---Bobbie-G

has push kit been installed? this elimantes the seat switch,

 

[Skidder Dave]

Apologies I took so long to provide an update. My Bobcat has been sitting there, unable to move (outdoors) since November with me waiting for nice weather to work on it. I tore into it finally March 20. I bench tested the traction lock solenoid - full current and hold current (from a bench battery) both work to pull in the traction lock plunger. BUT I bought a new solenoid anyway ($170-ish) - installed it, it did not solve the problem. From prior testing, I suspected "no ground to solenoid" in the machine wiring - I installed a spliced ground wire direct to the solenoid black ground wire - nope, no change. I thought perhaps the actual mechanical traction block had disconnected from the solenoid plunger - tore into it again - the block is attached, and moving freely in the guides - not the problem. My final diagnoses is that the full pull current is not coming in from the BICS to reach the solenoid. When I start the Bobcat, and press the Traction Lock Override button, the BICS diagnostic lights X4 all light up green, indicating (I think) that the appropriate solenoid signals are being issued, but the (new) solenoid just does not retract the traction block. I have finally surrendered to this problem - I removed the physical traction block, plunger, and associated springs, etc. and saved all the parts for posterity. I reinstalled the (old) solenoid, just to "seal" the traction lock cavity. I still have to press the Traction Lock Override button to enable the tool operation, but at least now I can drive it and work it. Woohoo! Now all I have to remember is - "NEVER park the Bobcat on a hill, ALWAYS park on level ground, with the tool firmly planted on the ground". All in all, a very frustrating experience. I would have called in the cavalry, but the nearest Bobcat dealer/service is 50 miles away, and not cheap (Chillicothe to Hilliard OH). Hey, it's a 1976 machine (I think), old and rusty, but it runs good (after LOTS of repairs by me), and it works fine - except for this darn Traction Lock problem. Wish I could have documented a more definitive solution. But now ya know!

 

[walio123]

Apologies I took so long to provide an update. My Bobcat has been sitting there, unable to move (outdoors) since November with me waiting for nice weather to work on it. I tore into it finally March 20. I bench tested the traction lock solenoid - full current and hold current (from a bench battery) both work to pull in the traction lock plunger. BUT I bought a new solenoid anyway ($170-ish) - installed it, it did not solve the problem. From prior testing, I suspected "no ground to solenoid" in the machine wiring - I installed a spliced ground wire direct to the solenoid black ground wire - nope, no change. I thought perhaps the actual mechanical traction block had disconnected from the solenoid plunger - tore into it again - the block is attached, and moving freely in the guides - not the problem. My final diagnoses is that the full pull current is not coming in from the BICS to reach the solenoid. When I start the Bobcat, and press the Traction Lock Override button, the BICS diagnostic lights X4 all light up green, indicating (I think) that the appropriate solenoid signals are being issued, but the (new) solenoid just does not retract the traction block. I have finally surrendered to this problem - I removed the physical traction block, plunger, and associated springs, etc. and saved all the parts for posterity. I reinstalled the (old) solenoid, just to "seal" the traction lock cavity. I still have to press the Traction Lock Override button to enable the tool operation, but at least now I can drive it and work it. Woohoo! Now all I have to remember is - "NEVER park the Bobcat on a hill, ALWAYS park on level ground, with the tool firmly planted on the ground". All in all, a very frustrating experience. I would have called in the cavalry, but the nearest Bobcat dealer/service is 50 miles away, and not cheap (Chillicothe to Hilliard OH). Hey, it's a 1976 machine (I think), old and rusty, but it runs good (after LOTS of repairs by me), and it works fine - except for this darn Traction Lock problem. Wish I could have documented a more definitive solution. But now ya know!

Check that the parking brake pedal button is working correctly and that there are no damaged wires in the parking brake pedal circuit. If everything is OK, check for a relay that controls the solenoid on the parking brake, it may be faulty. Relays are usually below the air filter.Even if there is an internal fault in the controller, there is a way to add a button to press and hold for 5-6 seconds to send the solenoid pull- voltage as long as you have the hold-up voltage and have a machine with a parking brake. Without it, it's pretty dangerous and you have to be very careful. Especially when transporting it on trailer, you have to bind the machine very well. Also when you work on the slopes,if the engine stops for some reason, there is no force to keep skidsteer with rised bucket on the slope ....

 

[Skidder Dave]

Check that the parking brake pedal button is working correctly and that there are no damaged wires in the parking brake pedal circuit. If everything is OK, check for a relay that controls the solenoid on the parking brake, it may be faulty. Relays are usually below the air filter.Even if there is an internal fault in the controller, there is a way to add a button to press and hold for 5-6 seconds to send the solenoid pull- voltage as long as you have the hold-up voltage and have a machine with a parking brake. Without it, it's pretty dangerous and you have to be very careful. Especially when transporting it on trailer, you have to bind the machine very well. Also when you work on the slopes,if the engine stops for some reason, there is no force to keep skidsteer with rised bucket on the slope ....

Thanks wallo123. You gave me a few more things to try. I fully understand the safety issues. I see the "hold" current comes from the BICS, but the "pull" current comes from the Brake Solenoid. I recently put in a new Brake sol but I will check it out. I also see that the Brake switch goes directly to the BICS. Since I am getting a Green Traction Lock light on the BICS, I'm thinking that the Brake signal input and the Hold signal output are probably good, but who knows, I'm leaning toward the Brake Solenoid being bad right now. But I have to tear Bob down AGAIN to put in the mechanical Traction Lock stuff back in to try it. Crap. Oh my achin' back.

 

[bobbie-g]

Thanks wallo123. You gave me a few more things to try. I fully understand the safety issues. I see the "hold" current comes from the BICS, but the "pull" current comes from the Brake Solenoid. I recently put in a new Brake sol but I will check it out. I also see that the Brake switch goes directly to the BICS. Since I am getting a Green Traction Lock light on the BICS, I'm thinking that the Brake signal input and the Hold signal output are probably good, but who knows, I'm leaning toward the Brake Solenoid being bad right now. But I have to tear Bob down AGAIN to put in the mechanical Traction Lock stuff back in to try it. Crap. Oh my achin' back.

Skidder Dave, if this were easy, someone else would already have done it..... Once you have the brake solenoid loose, leave it connected electrically and try turning on the ignition switch and see if it retracts as it should. No need to install it and bolt it down just to see if it's working. That may save your back just a bit. You could also exercise the foot safety brake switch to make sure it's working correctly also. And it's a lot easier to access the brake solenoid if the lift arms are up. Use that lift arm safety bar! This forum needs you in one piece so you can tell us what the resolution on this problem is! ---Bobbie-G

 

[walio123]

Skidder Dave, if this were easy, someone else would already have done it..... Once you have the brake solenoid loose, leave it connected electrically and try turning on the ignition switch and see if it retracts as it should. No need to install it and bolt it down just to see if it's working. That may save your back just a bit. You could also exercise the foot safety brake switch to make sure it's working correctly also. And it's a lot easier to access the brake solenoid if the lift arms are up. Use that lift arm safety bar! This forum needs you in one piece so you can tell us what the resolution on this problem is! ---Bobbie-G

Current for pulling also comes from the controller, but it goes through a relay because it takes a lot more power to pull it out. The relay should be around the air filter, there are 4-5 relays. Check them if they work well. To pull the solenoid, you need a voltage of just 4-5 seconds then hold will work , so you can always add a button and a relay for that job if you do not find the fault or it's in the controller

 

[Skidder Dave]

Current for pulling also comes from the controller, but it goes through a relay because it takes a lot more power to pull it out. The relay should be around the air filter, there are 4-5 relays. Check them if they work well. To pull the solenoid, you need a voltage of just 4-5 seconds then hold will work , so you can always add a button and a relay for that job if you do not find the fault or it's in the controller

Thanks go to both Walio123 and Bobbi-G for their suggestions and concern for my safety... obviously fixing my Bobcat ("Bob") has not been a priority. But I said to myself "Today is the Day!" and got on it again. First checked the brake pedal circuit - it's OK. checked the fuse (again) - OK - more on this later. Starting ringing out between battery -to-fuse and fuse-to-relay - WEIRD voltage of 7.2V at the relay - some sort of backfeed voltage maybe?. Hmmm... Definitely something wrong in the fuse-to-relay wiring. Starting tracing physical harness wiring from relay to fuse boxes (there are 2 fuse boxes stacked one on top of the other). AHA moment... I long ago purchased a hard copy shop manual for Bob. It has been a blessing to have it. BUT the manual contributed to my ongoing debug problem on this one. I bought Bob from a guy who bought it at an auction - $5000 - a steal I thought. Since then, Almost ALL new hoses, new starter, new battery and hookup cables, lotsa relays, new cab switches, new traction lock retract solenoid and on-and-on. Now this ugly traction lock problem. Turns out THE MANUAL shows the top fuse box - 2 - 10A fuses and 2 - 15A fuses and the bottom fuse box 4 - 25A fuses. Bob physically matched this fuse arrangement exactly. I have always been checking fuse 7 in the bottom fuse box for the brake and found it OK. But somewhere along the line, (maybe even from the factory), prior to my purchase of Bob, the top and bottom fuse boxes were interchanged, and whoever switched them kept the same fuse arrangement as in the shop manual instead of also switching the fuse arrangement top-to-bottom to follow the boxes. Did you follow that? The top box now should have had the 4 - 25A fuses, but instead had 2 - 10A and 2 - 15A and vice versa. So the fuse I SHOULD have been checking was in the top fuse box, not the bottom as shown in the shop manual, AND the fuse was undersized (and blown). New 25A fuse - problem fixed. And I made sure ALL fuses are now correct. I feel sooo stupid for not finding this sooner. But the sound of that retract solenoid kicking in is the sweetest sound I've heard in a while. Woo Hoo! Thanks again to SkidSteerForum for your help!

 

[Skidder Dave]

Thanks go to both Walio123 and Bobbi-G for their suggestions and concern for my safety... obviously fixing my Bobcat ("Bob") has not been a priority. But I said to myself "Today is the Day!" and got on it again. First checked the brake pedal circuit - it's OK. checked the fuse (again) - OK - more on this later. Starting ringing out between battery -to-fuse and fuse-to-relay - WEIRD voltage of 7.2V at the relay - some sort of backfeed voltage maybe?. Hmmm... Definitely something wrong in the fuse-to-relay wiring. Starting tracing physical harness wiring from relay to fuse boxes (there are 2 fuse boxes stacked one on top of the other). AHA moment... I long ago purchased a hard copy shop manual for Bob. It has been a blessing to have it. BUT the manual contributed to my ongoing debug problem on this one. I bought Bob from a guy who bought it at an auction - $5000 - a steal I thought. Since then, Almost ALL new hoses, new starter, new battery and hookup cables, lotsa relays, new cab switches, new traction lock retract solenoid and on-and-on. Now this ugly traction lock problem. Turns out THE MANUAL shows the top fuse box - 2 - 10A fuses and 2 - 15A fuses and the bottom fuse box 4 - 25A fuses. Bob physically matched this fuse arrangement exactly. I have always been checking fuse 7 in the bottom fuse box for the brake and found it OK. But somewhere along the line, (maybe even from the factory), prior to my purchase of Bob, the top and bottom fuse boxes were interchanged, and whoever switched them kept the same fuse arrangement as in the shop manual instead of also switching the fuse arrangement top-to-bottom to follow the boxes. Did you follow that? The top box now should have had the 4 - 25A fuses, but instead had 2 - 10A and 2 - 15A and vice versa. So the fuse I SHOULD have been checking was in the top fuse box, not the bottom as shown in the shop manual, AND the fuse was undersized (and blown). New 25A fuse - problem fixed. And I made sure ALL fuses are now correct. I feel sooo stupid for not finding this sooner. But the sound of that retract solenoid kicking in is the sweetest sound I've heard in a while. Woo Hoo! Thanks again to SkidSteerForum for your help!

I should add that I now think the weird 7.2V I was seeing was probably the "hold" current voltage from the BICS. But since the fuse was blown, the full 12V "pull" voltage was not reaching the traction lock retract solenoid, so the plunger never got retracted enough to the point where the lower hold current could take over. Maybe.... or maybe not...

 

[bobbie-g]

I should add that I now think the weird 7.2V I was seeing was probably the "hold" current voltage from the BICS. But since the fuse was blown, the full 12V "pull" voltage was not reaching the traction lock retract solenoid, so the plunger never got retracted enough to the point where the lower hold current could take over. Maybe.... or maybe not...

Dave, tnx very much for the feedback to the forum. Wish everyone would do that! Good luck (continued) with "Bob". ---Bobbie-G