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Brakes activating at hookup


Bill LeMosy

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This morning we hooked up. The moment we connected 7-way electric to the truck, the fifth wheel brakes activated as if the breakaway switch were pulled out. But it's not. In fact, I can't pull the breakaway switch out of its socket even with full body weight.

 

The HDT has a BrakeSmart controller. The fifth wheel has Dexter disk brakes (electric-controlled hydraulic setup). The rig moves fine without electric connected.

 

Any clues out there what might be going on?

 

 

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I would check the breakaway switch. Sounds like it has malfunctioned, seizing the pin and causing the brakes to activate which has drained the breakaway battery. When you plug into the truck it supplys the needed power to activate the brakes again.

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Thanks for the responses.

 

I, too, was figuring the breakaway switch was the problem. Perhaps if I can get somebody with a different truck to hook up electrical with our fifth wheel, we'll know whether the BrakeSmart or some other issue in the Volvo is involved.

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Did you change anything in the hookup wiring? I had this happen once when they changed out the plug at the back of the truck. We apparently had a bad new plug. I put the old one back on at it worked fine.

 

As soon as we hooked up the plug I could hear the pump come on and apply the brakes.

 

Brad

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Since you can't get the plug out of the breakaway switch it has to be replaced. Cut the blue wire and tape up both ends. If it now works the switch is the problem. If that doesn't fix the problem, keep looking but don't forget to replace the switch.

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When we disconnected the BrakeSmart, we were able to hook up without activating the fifth wheel brakes and still have lights. Tomorrow we'll get our rig over to the RV repair folks.

 

I wish I'd seen Ronbo's post about cutting the wire to the breakaway switch. I'd have done that before unplugging the brake controller. While the Volvo just had a complete brake job at Nextran and should be able to handle stopping the rig, I'd still rather have dem dar trailer brakes functioning.

 

Anyway, we replaced the truck's 7-way plug in Hutchison this past October; it has been working fine until now; the breakaway switch remains frozen in place; and the BrakeSmart is far from new. I foresee a long chat with the RV repair tech(s).

 

Thanks for the input, folks.

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The brakes are now working. We began by replacing the frozen breakaway switch; no effect. Turned out the 7-way plug was the problem. My question: Is there any reason the Volvo dealer (Nextran in Auburndale, FL) would have altered wiring of the plug? We had them do the whole preventive maintenance routine, and they repaired a turn signal light that was not working, plus they replaced the wiring harness on the engine. One of the folks at the RV service department wondered whether they might have set it up for a semi.

 

Everything seems to be working fine now. But this here HDT newbie is curious ... and wants to make sure the problem doesn't happen again.

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EZConnector.

 

Bill, I've been thru both truck and trailer issues over the last 4 months. I've found Volvo people don't like going south of the truck and Trailer people don't like going north of the trailer. The point of demarcation seems to be the rv plug and socket.

My rig has had issues with the trailer running lights twice. Twice I got it repaired without replacing anything, bad connection maybe, not sure.

 

The EZ connector is on my hit list of things to replace. If I get to the Western Rally outside of Boise in June, I'll have both receptacle and cord shipped to site and either get the switch out done professionally or if it looks simple enough, tackle it myself, but by my own admission, I'm no gearhead. In the meantime, to get my mind wrapped around it, I'll start tracing back the various cable wires to their destination on the trailer. Going to the Rally will also give me an opportunity to practice the English trifle recipe found when clearing out mom's condo after her passing a couple of months ago and a pulled pork recipe using root beer and barbeque sauce. Both seem to have worked first time around.

 

The issue, I found, was the pictures of the plugs and receptacles on the Jackalopee paperwork were not clear. Terminology needs to be clearer. Are we referring to the truck receptacle or the trailer plug cap on the end of the cord. Also from which direction are we looking at it.

 

There are pictures around clarifying what you are looking at and from which direction. If you are able to get hold of them, possibly from members here, you can check the wiring to the truck receptacle yourself. The receptacle terminals are numbered and a color and job description assigned to each color.

 

If you do this, clean the contacts on both the truck and trailer end.. your wife's emery board for her fingernails comes to mind. You'd need to cut it down to make it narrower. Play dumb if she asks if you've seen it and destroy all incriminating evidence.

 

If you don't have a Jackalopee, I'd suggest you get one. It will tell you with the led's whether power is coming to it from the truck side and if power is being sent to the trailer from the other side. As someone commented on my " Loss of trailer lights" topic, the Jackalopee helps narrow the search.

 

There is a red led on each circuit, ie, left turn signal, right, running lights etc. So for example if you turn on your running lights, the red led will light up on the left side of the box saying it is getting power and a second red led will light up on the right side of the box saying it is sending power downstream. From there I went to the truck receptacle.

 

Others may be able to explain it better.

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If I get to the Western Rally outside of Boise in June, I'll have both receptacle and cord shipped to site and either get the switch out done professionally or if it looks simple enough, tackle it myself, but by my own admission, I'm no gearhead.

Roger, if you do make it to the WCR I would be happy to help with this project. I've been thinking of switching to the EZ Connectors as well, I just haven't pulled the trigger yet. I would recommend getting the Adapter from the EZ Connector to the standard 7 pin RV connector just in case someone else has to tow your trailer for some reason though.

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I think you may have got you " wires" crossed when you had the Volvo folks fix your broken "light"'

A simple tester like this can help out if "wire" challenged or no Jackalopee in the circuit.

http://www.amazon.com/CURT-58270-12V-Connector-Tester/dp/B001EOWQY4

Just tried to order one but Amazon doesn't recognize Canadian provinces or our postal codes of letters and numbers.

 

Also that tester would only work on the truck or powered end wouldn't it?

 

How would you test the trailer end?

 

I'm going out on a limb here but if there is a charging circuit from the truck to the trailer batteries and the trailer is disconnected from the truck could that same lead be used as a hot and then a jumper made to go from that terminal on the plug to the other terminals on that same plug to see if they are getting power??

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That checks the truck receptacle not the trailer....am I missing something?? I'm looking for something to test the trailer.

 

That looks like the post a couple up.

 

The one tester is all over EBay so I'll get one shipped here. It'll arrive before the end of the week. Still need a way to check the trailer.

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Randy figured this could be done by jumping the power and running lite lead in the plug itself. So if that can be done, why can't the black or hot lead be used for the power and a jumper to the various other trailer lite functions, left, rt and backup lites for instance?

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You can build a tester for the trailer pretty easy if you want to mess with the electrical parts. Some switches, relays and power supply would do it. It might make a good project to write up. You can buy these, of course, but I'd bet they are pretty "proud" of them.

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