BAC Forum
General Boards => Technical Support => Topic started by: Les Brandt on September 20, 2014, 09:12:06 PM
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Will a bad sensor cause one of the hydraulic jacks not to lift? I have a problem with my right front not retracting.
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Les,
What kind of leveling system do you have on your coach?
Karl
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Les,
What kind of leveling system do you have on your coach?
Karl
Hi Karl,
Mine is the SMC Hydraulic system off the frame.
My system used to make an audible sound when it was "thinking" just before final level. That stopped as well. The "All Up" light stays on even when the right front Jack was down.
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Les,
I think we discussed this once before. Can you use the manual retract and get the jack to come up? If not, something is definitely wrong. Will it do an auto level? If not, what do the lights do on the control panel? Does it do an air dump before it begins anything?
Just to make sure I understand. The all up light is on all the time and if so, that would explain the buzzer not sounding. Clearly if one jack is down and you still have the all up light on then something has happen to the logic. All of the jacks must be up for the switch to make contact. Once all the jack are up then, and only then can the all up light go on. This also turns the buzzer off.
Karl
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Les,
The reason the all up is illuminated while a jack is still down is because one of the push button switch sensors is staying pressed in when the jack drops down for leveling. The best fix is to change that one, but you may get some life out of it with some penetrating spray and working it up and down with a length of small board to help reach it. Those all up sensor/switches I think play no role on the operation of the control unit. My belief is that they are just wired in series and when all four are pressed in by the ram foot the light will illuminate. You might have someone watch from a safe position with a mirror and see if full retraction takes place while you hold manual retract....it should.
Later Ed
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Thanks guys. The coach is in the RV shop getting some unrelated other work done (not mechanical) so it's not here to diagnose. This will be one of my upcoming projects once the season for us is over in a few weeks.
I wish I was retired and could take the coach to Bend, OR but have to try to figure this out myself. No one around here is familiar with the SMC system and is scared to touch it.
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Les,
First, you need to know if the jack will go back up using the manual retract switch. If that does not work, you have a whole different problem. If the sensor/switch on the jack or jacks are bad, which I think is highly unlikely. This switch is a very heavy duty spring and gravity loaded switch. As the jack comes up the pad depresses the switch and makes contact. The rod is protected during driving and would not get dirt and grim as a general rule. The rod is only exposed while the jacks are down.
As Ed pointed out, when all four make contact, the all up light comes on and stops the buzzer. This all up light and buzzer are just for your information it is safe to drive. I believe it is part of the logic board as a simple relay function. Again, if it levels under auto mode and everything on the panel looks as it should after leveling is complete, Then your problem could just be the up solenoid for that jack is not working. If not, my guess is the control/logic board and BCS has a manual replacement system that work very well. BTW, I do not believer the jack up switch is available except in the used market.
Let us know, we are glad to help solve your problem.
Karl
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Thanks Karl.
I have to get the coach home and blocked up on semi level ground so I can get my "not so svelt" body body under it.
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Les,
You do not need to go to that much trouble. Just turn your right front wheel all the way to the right. Look behind the wheel and you can see the jack. It will also be much easier to work on the switch.
Karl
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DOH!
You guys have all the best ideas!
Thanks Karl
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Les,
I think this is the sensor switch made by Cole Hersee. I replaced two of mine in the front and the rubber boot certainly will help keep the dirt out. It is readily available from BCS or truck supply houses can order it. Double check and see if dimensions look right compared to yours.
http://www.colehersee.com/home/item/cat/151/90043-07/
Later Ed