Article [13] ST1300 - Wiring diagram : Trailer Isolation Relay

userzero

userzero

Joined
May 4, 2009
Messages
135
Location
Saguenay QC Canada
Bike
2008 ST1300
A member on this forum asked if I could provide him with some information on how to connect a Electrical Connection Trailer Isolation Relay on a ST1300.

I decided to draw a little wiring diagram with the correct color codes to make it easier.

For those who are not familiar with isolation relays, they act as a barrier between the motorcycle's wiring system and the trailer wiring. So anything can happen to the trailer, like short circuits, and it will not affect the motorcycle systems in any way. Some have them, many think they are not necessary. In any case, I sleep better knowing my trailer install cannot hurt the motorcycle's electronical systems.

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If anybody spots a mistake in the diagram or want to improve upon it, please let me know and I'll be happy to add your input.
 
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Re: Wiring diagram : Trailer Isolation Relay on ST 1300

Good diagram. Would even be able to translate for the ST1100.
Just might be helpful to point out which factory wire is tail light and which is brake light (green-yellow or black-brown). Those with a service manual should have no problem finding that info. Shouldn't make any difference if the colors are connected as shown but might help if needing to troubleshoot a problem after connecting it all up. When I decide to add this to my ST1100 I'll have to take pictures and post a translated diagram for that. I added an isolation trailer module to my Gold Wing many years ago. Have been thinking about pulling a trailer again, but not a pop-up camper like I had before.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

roadriderg said:
Good work, Just curious where did you mount your isolator?

Gary
Click to expand...

It's under the back seat, wedged in a recess right by the tail light assembly, under the tool kit. It's not mounted or bolted or anything, it's just wedged under there.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

Attached here is the wire diagram that I use when I build my own wire harness for a trailer using standard automotive relays (3) for a 5 wire trailer hook up. I only actually tap the bike turn and brake light wires to trigger the relays and do not touch the bike running light wires. Power on my bike comes from a fused isolation power panel I added that is only powered when the bike is turned on. This is an alternative to the wire harness from EC or any other vendor if you are handy doing your own wire work. You decide if you crimp or solder your wire connections. I prefer to solder mine.

Correction: I used to solder all my connections but in my old age I am getting lazy. I have lately been crimping the spade connectors for the relays and lathering the wire in dielectric grease. The crimp spade connectors are good ones and hold well. If I find a problem with any of these I will go back and solder them. But so far they have held up well. I still solder any other connections I make including splices and the connector pins and cover with heat shrink insulation. I WILL NOT USE those cheap SCOTCH (blue) crimp splice connectors as those are prone to poor connections and corroding over time and ending up causing many more problems. Those connectors are only acceptable for very temporary emergency situations where no other option is available.
trailer harness wiring.jpg
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Re: Wiring diagram : Trailer Isolation Relay on ST 1300

I actually think I can handle this one :eek:: The past has not been a real confidence builder.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

rjs987 said:
Attached here is the wire diagram that I use when I build my own wire harness for a trailer using standard automotive relays
Click to expand...
That's a great addition to this thread! Thanks!

rjs987 said:
You decide if you crimp or solder your wire connections. I prefer to solder mine.
Click to expand...
Same here! Soldering eliminates so many problems down the road.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

rackovanz said:
What is EC? Where did you get the harness?
Click to expand...

www.Electricalconnection.com trailer wire harness
The EC unit does the same thing but is just pre-built and ready to connect to your bike.

My diagram is for a harness that I build myself. I have thought of maybe using the EC unit but prefer to build my own (costs a lot less). I use 3 automotive type relays commonly available at discount auto parts stores and stranded automotive 16 or 18 gage wire (14 gage for the main power feed to the whole harness, also from the same stores. I plan to place the connections and relays in a small hobby box and put that under the seat in the storage space. I already have one hobby box with the relays for my extra LED tail lights and turn signals that I added last year. My home built setup only requires tapping 3 of the bike factory wires for relay triggers and (like the EC unit) does not get power from any factory wire, the most important part. I have found by experience that all lights are brighter and problems are eliminated if you only take power from the battery or an added fused panel powered from the battery.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

rjs987 said:
www.Electricalconnection.com trailer wire harness
My home built setup only requires tapping 3 of the bike factory wires for relay triggers and (like the EC unit) does not get power from any factory wire, the most important part.
Click to expand...

I agree, the wires supplying power to the stock tail lights are pretty small, so you don't want to load those too much by adding a Christmas tree on the back. That's the main advantage of having a separate circuit to supply power to the trailer through the isolation relay.

The only advantage of a commercially available unit like the EC isolation relay over a home made version like rjs987's is that it is smaller in size and there is less work involved.

Some claim that mechanical relays induce electrical noise in electronic circuits (from arcing when the contacts open and close), and that the noise produced could in turn induce irregularities in sensor readings like ABS sensors, for example. Before buying the isolation relay, I searched on the net for some time and never could find one instance where a trailer harness had caused a malfunction in the ABS system of a motorcycle. In fact, I have added a mechanical relay to supply power to my freeway blasters and never had any problems whatsoever. All motorcycles have mechanical relays for the horns and other things, so they must not be so bad!

I don't regret my choice, but the DIY alternative is a really good one.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

After thinking of my diagram overnight I realized I over stated the required fuse amps needed. I will change that tonight in the diagram. Basically you can cut the amps to 15 amps for the main supply power fuse for the trailer and 5 amps for each leg. Was trying to remember what I had used the last time I built this harness.
Perhaps keep the running and brake lights at 7 amps since sometimes those can add up to more amps on a trailer. LED lighting would likely let you cut the amps down to maybe 7 amps for the main fuse and 3 amps for the individual legs.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

Updated/corrected diagram uploaded to post #6.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

I just bought a Bushtec trailer, used. The original owner cut the bike end of the Bushtec plug very short, about 1" hanging out of the plug. I just spoke to Lewis at EC. He is familiar with the ST1300 although they don't show a harness specifically designed for the ST1300. He knows they have made them in the past and is checking with his colleagues. He said they are grabbing signal from stop/turn/tail from the actual bulb socket. He also said he could supply me with a new, 6-pin flat, Weathergard plug and terminals that mates to the Bushtec. Bushtec wants $79 for their universal isolator harness. That sounds pretty pricey to me. Bushtec also has a separate circuit (accy) for the light inside the trailer. Lewis said some folks splice it with the green (tail) circuit to act as a switched circuit instead of direct to battery. Any words of wisdom before I embark on this adventure?

Thanks


Jeff
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

When I had the uni-go I got the universal trailer isolator from EC and it worked well... I think I used the white wire to a fuzeblock to get power for the interal cig ligher in the trailer.

Lewis knows his stuff that's for sure.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

Hello everyone:
I am just in the process of wiring my 2005 ST1300ABS. My Kompact Kamp trailer is 4 prong. I have all of the wiring from EC. Does anyone have a simple diagram for wiring the bike to 4 prong?
Thanks.
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

You need to get a 2-3 wire taillight converter. Most automotive stores and trailer shops have 'em. Or look at that big place online that ships for free.

The wiring diagram will be in there. The specific wires on your bike will be found in the back section under the passenger seat. Under there is also a good place to hide the converter to keep it out of the weather.

T
 
Re: Wiring diagram : Trailer Isolation Relay on ST 1300

Last year I picked up a Kompact Kamp Mini-Mate camper that was wired for 4 wire system. I towed it home from Florida with my Corolla and had to use a 5 to 4 wire converter to get that to plug in. Almost all foreign company cars are naturally a 5 wire system as are almost all motorcycles (only American company cars have a 4 wire system). It always puzzles me why anyone makes a motorcycle trailer with a 4 wire connector. Anyway, as soon as I got it home I restored the camper to the way it was from the factory... to a 5 wire connector. Their trailers and campers normally come from the factory as a 5 wire system, with separate turn signals (amber) from the brake lamps (red). I now plan to simply connect a 5 wire connector in my new Corolla (got rid of the older one I had last year) and do away with the converter.

If you prefer to keep the 4 wire connectors then do as others have mentioned and get a 4 wire to 5 wire converter for the bike. ElectricalConnection.com has these at:
http://www.electricalconnection.com/wire-harnesses/hrns-trailer.htm
They will also come with the electrical wire diagram for the hook up. You cannot simply connect the wires on your bike for a 4 wire connector or you wil be missing either brakes or a turn signal or both. There must be an electronic converter to change the signals. I think it's cheaper (just a few wires) to make the trailer a 5 wire system but that's just me.
 
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