getting power to electric brakes - Fiberglass RV
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Old 10-28-2020, 01:26 PM   #1
MJo
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Name: Mary Jo
Trailer: 2020 Scamp w/2004 Volvo XC-70
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getting power to electric brakes

I purchased electric brakes, after being told that I had a 7 wire connection on my Volvo brake package. Turns out that I only have 4 wire so Scamp had a 7 wire trailer to 4 wire car connector so that I was able to get home with all the lights I needed, but no electric brakes. Can I give the electric brakes power without having to rewire the whole trailer package on my Volvo? (add a wire from a constant on light on the rear of my Volvo and thread it in to 7 wire trailer?).
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Old 10-28-2020, 01:43 PM   #2
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Quote:
Originally Posted by MJo View Post
I purchased electric brakes, after being told that I had a 7 wire connection on my Volvo brake package. Turns out that I only have 4 wire so Scamp had a 7 wire trailer to 4 wire car connector so that I was able to get home with all the lights I needed, but no electric brakes. Can I give the electric brakes power without having to rewire the whole trailer package on my Volvo? (add a wire from a constant on light on the rear of my Volvo and thread it in to 7 wire trailer?).
Short answer is ... NO.
You will need to have a brake controller installed and an RV plug installed on your Volvo.
Also you might want to have a fused and switched wire installed to charge your trailer battery while driving down the road... Or have a battery isolator installed and a charge wire for the same purpose.
I always do this stuff myself but Many folks have been satisfied with having U-Haul do the installation. Probably a couple hundred dollars plus the price of the controller.
Get it done... it will prove worth the investment.
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Old 10-28-2020, 03:49 PM   #3
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Floyd is right. No. You’ll need a higher amp circuit that originates up front to run the controller. And at least one wire going back to the rear, preferably also a dedicated ground. That hot will have to be switched such that it is on with the key. Number 12 wires would be good.
As mentioned, a charging wire is also important.
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Old 10-28-2020, 05:24 PM   #4
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Name: Mary Jo
Trailer: 2020 Scamp w/2004 Volvo XC-70
Massachusetts
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when I ordered the electric brakes, $500.”. Scamp installed a “wireless brake controller, $350.” along with the electric brakes. I just need power to the brakes, don”t I ? Won’t the wireless operate the brakes if they have power? (I have a remote on the keychain to operate the controller to adjust the brakes so that they don’t act too soon or too late with my car’s brakes.)
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Old 10-28-2020, 05:36 PM   #5
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when I ordered the electric brakes, $500.Ē. Scamp installed a ďwireless brake controller, $350.Ē along with the electric brakes. I just need power to the brakes, donĒt I ? Wonít the wireless operate the brakes if they have power? (I have a remote on the keychain to operate the controller to adjust the brakes so that they donít act too soon or too late with my carís brakes.)
That setup will get the brake power from the trailer's battery. smaller brakes like on a scamp likely draw around 3 amps each at maximum braking force, or 6 amps total for the two brakes...
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Old 10-28-2020, 05:51 PM   #6
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Its late (for me) so correct me is I am wrong... but (even though I usually dont suggest a "wireless" brake controller), this seems like the perfect situation for a controller like the Autowbrake . I think all you would need to add is a wire directly from the Volvo battery to the controller which is mounted on the trailer. No other alteration to the Volvo would be required. Usually that would be via a 7 pin connector but could use the 4 pin and a seperate single wire connector from the veh battery Positive post. An appropriate circuit breaker at the battery is also called for and a seperate ground (negative) to the battery is good insurance. Please dont tap into the Volvo lights wiring for the power to the trailer's brake's magnets. Also dont use the trailer's battery for the brake power (except for a break-away switch).

BTW, I am one that thinks the charge line (to charge the trailer's battery when driving from the tow veh alternator), is not all that important. It depends on your power use, travel habits, etc.
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Old 10-28-2020, 05:54 PM   #7
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Name: Mary Jo
Trailer: 2020 Scamp w/2004 Volvo XC-70
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getting power to electric brakes

so, Iím not an ďelectric person,Ē I depend on 2 of my sons for that, But, what you said sounds like my electric brakes are getting power from the battery on the Scamp, which is recharged when I drive. so I still have the 7 to 4 situation on the trailer hitch, how does this all fit in with having the electric brakes work? Donít they need some sort of car connection even though I have a remote controller on my keychain? so far Volvo and my local RV dealer say they donít work on this sort of problem. Can you send a word diagram: step 1, step 2, etc? I managed fine without having the use of my electric brakes but I am told some states require them. ??
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Old 10-28-2020, 07:10 PM   #8
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Quote:
Originally Posted by MJo View Post
so, Iím not an ďelectric person,Ē I depend on 2 of my sons for that, But, what you said sounds like my electric brakes are getting power from the battery on the Scamp, which is recharged when I drive. so I still have the 7 to 4 situation on the trailer hitch, how does this all fit in with having the electric brakes work? Donít they need some sort of car connection even though I have a remote controller on my keychain? so far Volvo and my local RV dealer say they donít work on this sort of problem. Can you send a word diagram: step 1, step 2, etc? I managed fine without having the use of my electric brakes but I am told some states require them. ??
The standard Electric brakes get the power from the tow vehicle. You need a breakaway switch that applies power to the electric brakes from a battery that is on the camper. That can be the camper battery or an special battery just for the breakaway system. Check Etrailer, (Breakaway kit with charger and switch)

Now - The camper battery and/or breakaway battery- If you want to charge them while driving, You need a seperate wire from your tow vehicle.

all of this is not really complicated but if you are not electrically savy I suggest you search for a company that installs Hitches or just go to an RV dealer. You will need the break controller and you should be able to get one that installs easy. The Hitch and/or RV dealer will have the items.

Search Etrailer for answers
https://www.etrailer.com/vehicle-fin...0&HHMake=Volvo
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Old 10-28-2020, 07:11 PM   #9
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Originally Posted by MJo View Post
....even though I have a remote controller on my keychain?..
Is that a brake controller on your keychain? You first said you had lights but no brakes. Now it sounds like you have a brake controller but if it is functional is not clear. I think we need a lot more information from you to provide valid advice, and I am not sure you know what information is needed. So I suggest that you continue to look for a local trailer shop or auto place that can help.. and that is almost surely not your local Volvo dealer.

But of you want to persist here.. then post a lot of details. Post info on the keychain, post photos of anything Scamp did for you, etc....
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Old 10-28-2020, 07:59 PM   #10
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Name: Mary Jo
Trailer: 2020 Scamp w/2004 Volvo XC-70
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I’ll ask Scamp what i have. I have a remote on my keychain to control the controller and I have a wire that loops around the hitch that if the Scamp comes loose from the car’s hitch, the wire pulls from a 2x4 inch box connected to the trailer front and makes the trailer brakes stop the trailer and I bought electric brakes and a brake controller. I’ll ask Scamp what I need to make the electric brakes work. All I know is that i have a 4 wire connector and bought a part that has a 7 wire “female” to 4 wire “male” to hook my car to the Scamp.
hope my description didn’t offend anyone, but that’s what i was told.
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Old 10-28-2020, 09:51 PM   #11
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Mary Jo,

it's easy to get overwhelmed with all of the different functions involved here.

But the simple set of functions are: 1.The tow vehicle needs to control the trailer brakes. 2. The trailer brakes need power to operate. 3. There must be a trailer break-away emergency switch involved that applies the brakes if the trailer becomes disconnected.

It sounds like you have a wireless controller installed on the trailer now, that is turned on or off by a remote on your keychain. It still needs to be powered to apply the brakes, and it seems Scamp has it connected to the trailer battery. This power can come from the tow vehicle, or in this case it seems, from the trailer battery. The trailer battery must be charged somehow, or it will not be able to continue to power the brakes, and since it is being charged, it will also power the interior lights, etc. So, a good power source from the tow vehicle, to the trailer battery, is important. It will serve two purposes, trailer brakes and interior lights. The breakaway system, in my view, is best powered by the trailer house battery too. This is because it is already there, and you will always be aware of its state of charge. If you choose a dedicated breakaway battery, you will likely not be aware if it is charged or not, and it adds complication. I took mine out of my trailer and wired the system to run on the house batteries.

Bottom line. Run a charging wire to the house batteries from the tow vehicle. Use the house batteries to run the brakes with your wireless system, as Scamp apparently designed it. Turn that wireless braking system on or off with your remote on the keychain. Use the house battery, instead of a dedicated battery, to power the breakaway system.

The charging wire that runs back from the tow vehicle, should also have a ground wire run with it to complete the circuit. Two wires straight to the house batteries, from the tow vehicle. It is best to have the charging wire disconnect when the ignition key is turned off, but not mandatory.

It seems you need to upgrade to a seven pin plug so all of this happens simply with one plug. The breakaway system is activated if the hitch disconnects. That causes the small cable to be pulled and switches on the emergency braking system. Normally it is never activated.

Besides all of the braking stuff, the house battery must be kept charged anyway. Otherwise it will fail, you won't have interior lights and the brakes won't work. By connecting it to the tow vehicle, you'll arrive with a fully charged battery.
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Old 10-28-2020, 10:28 PM   #12
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Originally Posted by gordon2 View Post
BTW, I am one that thinks the charge line (to charge the trailer's battery when driving from the tow veh alternator), is not all that important. It depends on your power use, travel habits, etc.
unless you have rooftop solar, or always camp with AC power, that power wire from the tug is the only way your battery gets charged.

When off grid, the trailer battery power is required for...
  1. internal lighting
  2. water pump
  3. ventilation fan
  4. furnace fan

and any other DC stuff you have.
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Old 10-28-2020, 11:08 PM   #13
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The brake controller that Scamp installed uses an inertia sensor to apply the trailer brakes. It works like a passenger pushing his foot against the floor when the driver hits the brakes. What you have now will work but the trailer battery will run down and you need a way to keep it charged from the tow vehicle. As Raspy said, a 7 pin connector on the car is probably the best way to go. It would include the four wires you already have, with an improved ground, plus a line from the car battery. You don't need to use the pin meant for brakes with the system Scamp installed and the 7th for trailer back-up lights is optional. The line from the car battery should have a fuse and be wired so it shuts off when the car is off. The person doing the work should know how to accomplish all that.
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Old 10-28-2020, 11:18 PM   #14
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Just take it to a couple of shops that work on trailers and do things like install brakes and controllers. Then ask for a detailed estimate. That will give you the baseline of what needs to be done to make your trailer brakes functional. Plus since it is NOT as simple DIY job in most cases you will then have the estimates and information so that you can decide which company to hire for the work.
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Old 10-29-2020, 06:44 AM   #15
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Given the discussion thus far, OP would be well served by an in-person visit to someone who can walk her through the system and address any missing components. Not everything can be solved on the internet.
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Old 10-29-2020, 08:08 AM   #16
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From the description, it sounds like Scamp installed the Autowbrake on the trailer. The fob on your keychain is used for changing the amount of braking applied (the arrow shaped buttons) and to apply the brakes manually (the third button in the center). To test if the brakes are working, find a quiet street or a graveyard and slowly drive down a straightaway. While moving press and hold the center button and you should start to slow down and you should feel a drag if the brakes are working. After verifying that the brakes are working, you need to verify that the only wires going from the tow vehicle to the trailer are the 4 wires connected via the 4-pin plug. If that is truly the case, then as others have said you definitely will need to have a 5th wire run to bring power to the trailer. What I did for my Subaru Crosstrek is I mounted one of these adapters, plugged the 4-way connector into it and had a power lead run from the Crosstrek's battery to the power pin on the adapter:

https://www.amazon.com/RVGUARD-Trail...xpY2s9dHJ1ZQ==

Here is a link to information on the Autowbrake including how to use the fob:

https://getautowbrake.com/pages/installation

Make sure when getting the power lead installed that you tell them you want it to be off when the car is off. Otherwise when you stop for any length of time you would need to unplug the trailer since your car battery could be drained.
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Old 10-29-2020, 12:28 PM   #17
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Name: Mary Jo
Trailer: 2020 Scamp w/2004 Volvo XC-70
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power to electric brakes

Alex, thank you !!!! just what I have been looking for. I did buy the 4-7 adapter from Scamp but all that did is allow me to plug into the Scamp. It didnít change the fact that I had no brakes. I just ordered the adapter you posted from Amazon. Thatís a start, the Scamp adapter came with a wiring diagram to show me where the brake supply would come from on the 7 plug. Iíll see if this one solves my problem or at least gets me closer to solving with the extra wires. thank you again. MJo.
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Old 10-29-2020, 12:35 PM   #18
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You still need to run power from your tow vehicle battery to the power pin on the adapter from Amazon. The only other unknown would be if the power pin on the trailer's 7 way connector is hooked up or not. I would assume so since that would be standard but you never know...
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Old 10-29-2020, 12:52 PM   #19
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Name: Mary Jo
Trailer: 2020 Scamp w/2004 Volvo XC-70
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I ordered the electric brakes, after my Scamp was done. I was told I had a 7 wire connector and found out at Scamp that I donít. so the trailer connector should be set to go but I do have Ďan old Volvo guyí in town who acts like he can handle anything Volvo, so I may drive over and let him take a look and make everything work. Having that plug from Amazon will avoid him having to jury-rig something.
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Old 10-29-2020, 01:41 PM   #20
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I also had Scamp install the AuTowbrake when they replaced the axle (with 10 inch brakes) on my Scamp 13. They hooked up the wireless unit to the power supply from my battery. Which runs down the battery as told above.
I changed the wiring so that power comes from the tail light wire. The AoTowbrake manual has instructions for doing this. It does mean that you have to have the lights on as you drive.
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