|
I'm not intimately familiar with the U-Haul converter, but the trailer wiring story goes something like this.
A proper 4 lamp to 2 lamp Euro->US converter must have (at a mininum) wires that connect to the vehicle brake, left and right turn lamps plus a chassis ground. Most, but not all, will have a wire for the park lights. Some (the best kind) will have a +12v power line.
There are two basic kinds of Euro-US trailer light converters. If wired correctly, these units should not interfere with the vehicle bulb out sensor. Depending on quality and accidental misuse, both are subject to failure.
One is a small sealed unit that usually sells for under $20. You'll see these in places like WalMart. It gets power to run itself and the trailer lights from the vehicle light circuits. The unit consists of protective diodes, switching transistors and pull down resistors. There is a noticeable voltage drop through these units, as low as 5 volts DC out if really cheap transistors are used. The result is that the trailer lights, particularly the brake/turn lights will be very dim. They also tend to dim with age as the components inside start to fail. Add a slightly corroded socket and a bad ground connection between the trailer and vehicle and you'll have a stealth trailer -no visible lights. These units also tend to fry at the first sign of a short or overload. They are also capable of upsetting the bulb out sensor if cheap, unmatched components are used inside.
The next level up are the direct powered systems which cures the dim light problem and also allows more trailer lighting without blowing the vehicle lighting fuses. As the trailer lighting is separated there is even less of a chance of upsetting the bulb out sensor. These units consist of relays using the vehicle lighting circuits to control the relays which then feed battery power to the appropriate lights. Prices range from $25 to over $150 depending on the number, size and quality of the relays, the number of circuits supported and the amount of wiring and connectors supplied. Apart from the OEM variety, you can also get these through auto parts suppliers although they may or may not be an in-stock item.
When you order an OEM trailer wiring kit or towing package from a dealer you're normally getting a proper relay driven system. On SUV's you'll often find these boxes mounted under the hood or under the dash with a standard connector plug at the rear of the vehicle.
For installing a trailer wiring converter on your Volvo with a bulb out sensor, there are three things to know:
o Get the brake light source from a point before the bulb out sensor (like directly off the brake pedal switch -sometimes the 3rd brake light wire can also be used).
o Get the park/running light source from a point not on the bulb out sensor (like the license plate lights and sometimes the side marker lights).
o Make a solid ground connection to chassis bare metal. Protect from corrosion with something like OxGuard. Never rely on the hitch or chain as a ground circuit to the vehicle. Make the trailer ground connection at the lamp sockets rather than using the trailer chassis. When troubleshooting trailer light problems, 70% of the time it will be related to a bad ground connection.
|
