2nd Headlight


My 1992 European ST1100N had only one headlight connected. To make the second headlight working, usually it will do to simply connect the plugs for both headlights. On this older bike, it will however overload the switches and other electrical components.

I find that specially in wet conditions, one low headlight beam is insufficient for clear view on the road. Also switching from a single low beam to the double high beam is a huge difference. This is why it is preferable to connect the second low beam also. Unlike Pan European versions since 1995, my Dutch 1992 ST1100N has no relay for switching the low beam. This means that when the second headlight is made workable by just connecting it to the other, there is a high risk for burnt out switches and not only that; also, when using the passing switch, both low and high beam will shine. This will overload the system.
For this reason, I made some improvements to the electrical scheme:
1) With a switch, I can select whether or not to use the extra light. This is also fail safe in case of relay malfunction that could drain battery when engine is off.
2) When the switch is on, a "make" relay allows the light to come in with the other.
3) Whenever high beam is selected (Passing switch, or High beam switch), the 2nd low beam is disconnected by a "break" relay, thus preventing system overload.

I decided to include also an extra switch and power for auxiliary, in my case Navigation System.

Warning! Though generally both the Clymer and the Haynes manuals are considered to be good for th ST1100, the Haynes manual lacks the electrical schemes for other models than standard UK and US. Though differences between the schemes are usually small, in this particular case one has to be very careful.

01

01: First step was to make an electrical scheme.

02

02: The plug has no wire for the right low beam. Best solution is to pay a visit to the nearest (car)junkyard and grab anyone from a car with H4 bulbs. I took the white wire and connector out of the junkyard plug and placed it in mine.

03

03: Lots of solutions possible for placing the two extra relays. This is how I did it, though in the end the front relay proved to be a tight fit with the headlight housing.

04

04: A few pieces of aluminum and a little work with saw and file was all required to place this power connection. It may seem to be a strange location, but it can be reached easily without dismounting any part of the fairing.

05

05: Here the two relays in place. The wires are soldered together, with heat shrink over the connections. That in turn is all to be taped in and securely tightened with tie-wraps.

06

06: Normal positions for extra switches would be next to the knees on the fairing pockets. I choose positioning them on the dashboard cover left because of their seize and parts protruding. Note in this view that I made the connecting wires extra long to enable dismounting the panel without direct need to take the cables off.

07

07: Both switches barely fit in this position. I choose to put them on the left side because the right hand should stay on the throttle and the left one is free to operate the switches. Making the holes in this panel is difficult since it's shape does not allow clamping it.