Trailer wiring the right way?

Post by **Eddystone** » 08 Mar 2021, 05:30

I seem to recall reading somewhere that when installing a trailer you should not simply splice into the lights or you could have electrical issues that include false bad bulb indications. Is the some sort of guidance for doing this? Possibly a special Volvo harness? I have an S70 T5. Only plan to use this for VERY lightweight LOCAL hauling.

Post by **abscate** » 08 Mar 2021, 05:35

Here’s a simple way to just get tail lights on, which will keep 5-0 of your back...

Not legal for street use in the 53 States or Provinces, except PEI

The stock trailer harness from Volvo plugs into a receiving plug in the car, no vampire clips please, aka Scotchlocks

I’ll try and find my documentation this morning.

Post by **Eddystone** » 08 Mar 2021, 08:47

Vampire clips? I was reading the paper about a local Cleveland company that makes all sorts of connectors, and the story said these guys invented the alligator clip!

Post by **BEJinFbk** » 08 Mar 2021, 16:16

I think that Abscate is talking about 3M Scotchlocks.
Horrible crimp-through taps that were hawked as
time-saving, but have melted many a harness.
Occasionally torched the whole vehicle...

: 2530A1B9-2547-4D5F-BB46-A27FA6699803.jpeg (33.84 KiB) Viewed 709 times

Not to be confused with these little gems!

: 3E3CD6A0-F369-452E-8D85-6F1CE9094CB1.jpeg (35.89 KiB) Viewed 709 times

Awesome 3M telecom connectors also known as Magic Beans.
Great for 22-24 gauge solid core in comm rooms and splice cabinets everywhere!
But not for automotive use...

Doesn’t Volvo have an OEM adapter that just plugs in?

Post by **abscate** » 12 Mar 2021, 08:25

Here you go

Post by **kallekula** » 12 Mar 2021, 09:41

A few years back when I mounted the hitch on my S70 I bought one of them tow-box thingys. Basically it takes e.g. your blinker signal but just treats it as a signal. Box then delivers full power to blinker. You need to run a separate power line to it.
I bought it from Autozone, around $30?
Sorry for bad pics but I had the trunk loaded with firewood.

Post by **BlackBart** » 12 Mar 2021, 10:02

Mine has the hot coming right off the battery post clamp. I put an in-line fuse in it right next to the battery, and ran it down the bottom of the car tucked up safely and zip-tied often. In the trunk under the floor is a harness and connector similar to the one in Kallekula's photo above. It's connected to the lights per Abscate's diagrams. It's coiled up in the trunk - there's enough slack that it goes out under the rear hatch door and to the trailer harness. I attach the connection to the trailer tongue so it's not flapping around in the breeze, but enough slack for turning.

Post by **Eddystone** » 12 Mar 2021, 13:36

Thanks for all the trailer wiring info, people! I have already received a kit I ordered from Amazon for $17 that uses the battery to supply current to the lights and uses the factory "signal" as an input so that it doesn't load down the factory lighting. I'm sure this is what Kallekul and BlackBart are describing. I did not see one custom made for my car, so I bought the cheapest one I could find which is for a Lexus. The expense of these custom sets seems to be mainly in the special connectors that go right into the factory harness. This one was relatively inexpensive because it was relatively simple. Also, it might be because not many people tow with a Lexus and use their Land Rover instead for that. Things that don't sell on Amazon often get discounted. I will have to do some splicing somewhere down the road.

Post by **BlackBart** » 12 Mar 2021, 14:52

Mine may have come from the Uhaul store...(?)

Post by **kallekula** » 12 Mar 2021, 17:06

Mine was a universal from either Autozone or O'reillys.