Originally Posted by Clarky199
The 110 came with 4 roof lights on it...
I managed to trace all the wiring and it seems that each lamp is wired to the next along the roof then the final lamp is fed in through the roof.
The back cable runs to the back of my near side headlight on the main beam wire, it is then fed back to a relay, an inline fused red wire from the + on the battery then connects to the relay and it seems that a negative is being fed straight from the battery to the relay as well!
From what I can gather is should send the relay a command when full beam is activated and the lights come on, it should then switch off when full beam is taken off but for some reason it seems to either stick on for a few seconds (usually 20-30) or it just stays on all together even though the headlights are not on main beam any more.
I've noticed if I quickly flash the lights to let someone out of a junction the roof lights always seem to stick!
One can hook anything up any way they like, but in my opinion, those roof lights are hooked up incorrectly.
Do a search on 12V relays and study the leads. Typically they are:
30 Power source (+)
86 Switching (+)
85 Ground (-)
87 Power (+) to device isolated by the relay.
With the above scenario, when 86 is energized with (+), an electric coil inside closes a set of contacts that join 30 to 87.
This is the same way a binary computer worked back in the old days.
The purpose is to prevent all the current required to run the device from being drawn through the switching means.
If all these lights some knucklehead hooked up were powered off the high beams, it would melt the headlight and dipper switch because they are not designed to handle 3X the amperage load.
I suspect the PO only used the relay because in UK auxiliary lighting can only be on when the high beams are powered.
So the PO jackass followed the law to pass MOT as he took a drill to the roof.
Anyway, I suspect he used a single 20 or 30 amp relay that is now faulty.
In most states, you have to have off road lights covered when driving on a public road, so you're better off rewiring them to function from a separate switch, or remove them all together.
If they were wired "correctly" as intended, you'll find:
30 Battery (+)
86 High Beam (+)
87 (+) to ass clown roof lights.
I once drove a 110 in the rain with UD from Baltimore to Philadelphia, then solo down the eastern shore of MD/VA and across the tunnel to VA Beach in the rain with a steady drip on the back of my neck because some idiot had decided to drill a hole through the roof for extra lights.
The first thing I did was remove the lights and get out the alunina-weld and seal up the holes.