Diesel Gypsy

HDT Converter Wiring

There are quite a few ways to adapt the VOLVO trucks trailer wiring (3 wire system) to the standard RV trailer (2 wire system).
I did not feel like I wanted to CUT into the OEM wiring, and do irrepairable harm to that quality, waterproof wiring.
Close inspection revealed 2 OEM plugs at the rear under-side of the cab. These plugs had short lengths of wire connected to the tractors trailer wiring connector.
I unplugged them, and un-bolted the white wire #8 ground wire.
I opened the rear of the 7 pin trailer plug, and dissconnected the 7 wires.
I then lengthend those short pig-tails by 24". I used #10 wire with soldered & shrink wrapped joints.
This gave me two quick-connect wiring adaptors and a # 8 ground wire with lug, which could easily be plugged back into the VOLVO's OEM wiring at the rear underside of the cab.
Using an aluminum project / hobby box, I installed my powered "Hidden-Hitch" tail light converter, as pictured.
Using some good quality buss-bars I connected the truck wiring (visible on left side of box), to the inlet side of the light converter.
On the right side I wired in the RV trailer line.
I used all #10 & #12 wire for power & Trailer brake feed line (blue).
The covered/sealed hobby box is then bolted to the back of the cab, where the original commercial plug used to be.
The coil of wire (right-side in photo) runs to the female RV plug at the rear of the truck frame.

posted by Rick Lacombe (AKA-PSD_Tweaker) @ 1:15 PM