Small Black wire on Landing Gear C.Breaker?? - Montana Owners Club

jaybird · 11-02-2010, 01:59 PM

There's a small black wire that hooks on the right "Aux" stantion on the Landing Gear circuit breaker of my 2006 Monty. Does anyone know what it is or where it leads? My shop guy thinks its a ground wire for the converter. When I hook it up to the breaker now it over heats the system to danger(melting other wires) levels. I need to figure it out. Thru all my issues I now have everything working except for this puzzling wire. It runs something. Without it hooked up the landing gear works and so does the slides. One last hurdle I'll have it under control finally

BB_TX · 11-02-2010, 04:12 PM

Mine has the same black wire connected to the same terminal. Goes thru the metal panel into the underbelly so can't tell where it goes. But it can't be a ground wire since it connects to the hot breaker. May be the wire that keeps the battery charged. I don't see any other wire that would serve that purpose.

SlickWillie · 11-02-2010, 05:43 PM

I think Bill may be right. Strictly a guess, but I suspect that black wire might go to the junction box under the pin box (hot feed from truck). You might get your service guy to pull that cover and take a peek. Perhaps a short there.

Bill and Lisa · 11-03-2010, 08:27 AM

Jay Bird,
First, the rest of us all have that black wire so it does belong.
second, in your original post picture there was a second black wire that looked like a ground wire from the landing gear. If you are accidently hooking that up to the aux side of the breaker that would/could cause you problems.

My thought on the purpose of the black wire was it was the sensing line to the converter box to "measure" battery voltage to control the stage (output voltage) of the converter.

It could very well be a line coming in from the umbilical to the truck. My truck has 40 amp breaker that feeds the charging pin on the bargam connection and that little wire doesn't look like it could handle that much juice although the pink one to the landing gear motor is the same size and has a 30 amp fuse in it.......

So, a couple of questions. When you hook up this wire and things start to over heat:
1. Is the umbilical plugged into your truck?
2. Is the converter being supplied with AC power (i.e. your 30 amp or 50 amp cord is installed and plugged in?)

IF the answer to both questions is no and IF that small line comes from the umbilical there may be a short in the cord between the hot lead and ground. This would cause the battery to begin to discharge through that line which would generate some heat.

jaybird · 11-03-2010, 12:37 PM

This black wire on the right hand side of the pic hooked up to my CB is the one causing my grief. I need to know where it leads. I believe I have a short in this wire. Any ideas-Pretty Please

H. John Kohl · 11-03-2010, 12:56 PM

If you have a DC cut off switch in the service center it might go to that switch. If you have an OHM meter you can disconnect and check it for continuity.

SlickWillie · 11-03-2010, 02:40 PM

If you have the RV plug tucked in the pinbox, you might pull it out of there. Could be grounding the hot wire in the plug to the pinbox. That has been known to happen. Just guessing again. We've been gone all day, or I would have seen where the black wire goes on our rig.

John, I just can't see that wire going back to the converter. You could monitor the battery just as good off the #6 wire feeding the converter without running another 30' of wire.

jaybird · 11-03-2010, 02:50 PM

I'm confused-"If you have the RV plug tucked in the pinbox, you might pull it out of there" Can you go in to a touch more detail. I'm fishin for anything at this point

**Carl n Susan** · 11-03-2010, 03:12 PM

I am pretty sure Will is referring to the rare, but not unknown to happen, problem where the charge line in the RV plug contacts the pin box (likely a bolt protruding into the space) and causes a short. I believe Dennis Korchack had a problem with that same charge line shorting out some where in the front of the Montana and starting a fire. Fortunately he was there when it happened and prevented the total loss of the coach. But it still did a bunch of damage.

SlickWillie · 11-03-2010, 03:13 PM

When the RV is not connected to the tow vehicle, many folks will tuck the rv cord and plug up in the hollow part of the pinbox. The plug has one connector that is hot all the time. If it shorts to the metal pinbox, you can have a meltdown or fire. I was guilty of the same. I made an "s" hook and put it in one of the bolt holes and now stow the cord and plug on it.

Ha! Carl is a little faster on the trigger than I am.

jaybird · 11-03-2010, 04:14 PM

Wow-Something else to consider. What do I need to look for in the pinbox for trouble, and how do I fix??

jaybird · 11-03-2010, 04:36 PM

Actually now that I think of it, my issues with over heating wires happened 2 days after I unhooked the RV. It all started when I replaced my 50v Landing gear CB by accident camping with a 40 (I thought I was changing the slide CB which is weak). Once I landed the Monty the power sensor inside the Monty was screaming to unhook everything. A couple days later I tried to put on a new 50CB and all hell broke loose. I did something to that black wire to make it very hot and almost destroyed my wire system. Meltdown was happening before I intercepted power. I need to track thru the RV to find where that redhot black wire goes. Finally made an appt to a dealer on Monday so I can finally sleep at night. Just wish i could have figured it out.

H. John Kohl · 11-03-2010, 05:11 PM

The comment of the black wire going to the charging circuit from the truck could be true. As suggested check your 7pin plug and make sure it is not touching one of the bolts in the pin hitch area. That will ground the wire.

Bill and Lisa · 11-03-2010, 05:48 PM

Quote:

quote:Originally posted by SlickWillie

If you have the RV plug tucked in the pinbox, you might pull it out of there. Could be grounding the hot wire in the plug to the pinbox. That has been known to happen. Just guessing again. We've been gone all day, or I would have seen where the black wire goes on our rig.

John, I just can't see that wire going back to the converter. You could monitor the battery just as good off the #6 wire feeding the converter without running another 30' of wire.

Will, there is no #6 wire from the battery feeding the converter. The main line from the battery connects to one end of the DC bus bar and the output from the converter connects to the other end of the bus bar (although I have seen some where they connect via seperate lugs to the same end of the bus bar). The only thing the converter could sense off of the line between it and the DC Bus is the output voltage of the converter, which will always be higher than battery voltage, even if it is in the trickle charge stage of operation.

SlickWillie · 11-04-2010, 12:54 AM

If the battery and converter are tied together, whether it be through the panel or not, the voltage will equalize between the two. The only way this would be prevented is by a voltage blocking device in the line (diode), in which case it would not allow the battery to charge. You will measure the same voltage anywhere along this wire, thus, no need for another wire. At least that's the way I see this.

steves · 11-04-2010, 02:29 AM

Quote:

quote:Originally posted by SlickWillie

When the RV is not connected to the tow vehicle, many folks will tuck the rv cord and plug up in the hollow part of the pinbox. The plug has one connector that is hot all the time. If it shorts to the metal pinbox, you can have a meltdown or fire. I was guilty of the same. I made an "s" hook and put it in one of the bolt holes and now stow the cord and plug on it.

Ha! Carl is a little faster on the trigger than I am.

Never thought of that situation! I'll have to stop storing the cord there.

Bill and Lisa · 11-04-2010, 04:48 AM

Quote:

quote:Originally posted by SlickWillie

If the battery and converter are tied together, whether it be through the panel or not, the voltage will equalize between the two. The only way this would be prevented is by a voltage blocking device in the line (diode), in which case it would not allow the battery to charge. You will measure the same voltage anywhere along this wire, thus, no need for another wire. At least that's the way I see this.

Sorry, but according to the diagrams that came with my converter, the Voltage output is fixed for the various stages of the coverter. It will not "equalize". This voltage differential is what causes current to flow into the battery and recharge it. (V=IR). Current will decrease as the voltage difference between the battery and the converter decreases. In addition there will be some line loss of voltage due to the resistance of the wire so the exact voltage at the output of the converter will not be what is seen at the battery itself but it will be close. I can "rationalize" a sensing tap close to the battery to get a more accurate read on the battery voltage but we digress from the question.

I don't know what the little black wire is and that is what Jaybird needs help figuring out. Right now, the best answer I have heard so far is it is the charging line from the Bargman Umbilical, (how the truck can charge the battery while towing). There have been some suggestions on things to check to see if there is a short in that line resulting in the battery discharging (or trying to) through that line to ground and overheating in the process.

SlickWillie · 11-04-2010, 05:05 AM

Well, I can see we're not gonna agree on this one. I can assure you though, any wire that ties into the terminal on the breaker will read the same voltage, whether it is #6 or #10. Line loss will be minimal in either line. I would think charging demand would be based on converter current output; as the charge level of the battery rises, so does the voltage of the battery. Current output can be measured at the converter. IIRC, a fully charged 12 volt battery is about 12.5 VDC. As battery voltage increases to full charge, current demand on the converter decreases, thus the converter needs to drop output voltage so as to not overcharge the battery. JMHO

I took the cover off the junction box on our pinbox this morning. I've got to locate my electrical tape, and then I will check the wiring to see if the wire in question actually comes to the plug.

SlickWillie · 11-04-2010, 08:29 AM

I believe strongly that the black wire goes the the RV plug. I find a #10 black wire in the junction box that has 12 VDC, that also feeds the brake breakaway switch. I didn't lift the lug on the other end, as I didn't want to disconnect the battery or the converter. I followed the wire from the terminal on the breaker. It goes through the driver's side propane compartment, up into the front of the RV.

If I were trouble shooting that wire, I would remove the wire nut and separate the wires. If the problem is still there, it is in the wire between the breaker and pinbox. If that clears it up, I would look at the plug. The wires on the breakaway switch are so small, I think they would burn if they were drawing enough current to melt the 10 gauge wire. JMHO

jaybird · 11-04-2010, 01:46 PM

Slickwillie is the man. I finally turned my head away from the blackwire on the landing gear CB and low and behold SlickWillie nailed it. When I landed I threw the cord that attaches to my truck poer and it must have hit a screw that triggerd a melltown. The good news I hope I shut everything down beofre major damage. I retaped some exposed wiring, hooked eveything up but one last problem came up. Without hooking up to the truck, the left year tail light came on. Is it probable by looking at the photo that I need to replace the entire cord that hooks to the trucks electrical outlet. Please tell me this crazy delimia is almost over. Still don't no what the small black wire is on the landing gear CB but it ain't hot no more. Every single 5er in my storage unit has the cord stuffed in the pinbox---Thanks agian Montana Nation!!

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