Date: Mon, 05 Jun 2006 15:46:46 GMT From: Bob <uctraingnospamanet.com> Subject: Re: 95 towbar wiring
On Sun, 4 Jun 2006 21:54:54 +0100, "John Hudson" <mypcnospam.com> wrote: >If its coming from a main dealer it will be expensive. You do not use a >relay for rear lighting on a trailer.. Relays are only used when a power >supply is needed for a caravan fridge, etc. The relay only works when the >engine is running to avoid a flat battery if you forget to switch off the >appliance when the car is stopped. A relay for the connection between the >car lights and the trailer lights could be dangerous if it failed plus why >have a relay there anyway? Yes, you *do* use a relay. You do it because the cars existing wiring is only designed to handle a certain amount of current. The relay allows you to add only a minor amount of flow to the existing circuit and then the relay handles the load of the new lights. This is particularly important in a recent Saab since most of the wiring passes through a computer that controls all lighting. Overloading it is a really bad idea. As to reliability - you are seriously endangering it by not using a relay. The relay itself will be very reliable and last the life of the car. If you are concerned about failure, you could rig a "light failure" detector to the new circuits but I think it's overkill.
