Daytime Running Lights: A Simple Safety Conversion
by Robert Wolf
Blue Ridge Chapter BMW CCA Newsletter Mar/Apr 97
It's an idea which has come of age. Taking our cue from Canada, the US standards fro new car design will soon include a requirement for Daytime Running Lights. This system ties the headlamps operation to ignition power as motorcycles and interstate buses have for many years. Instrument cluster lamps and tail lamps are not powered until the headlamp switch is operated manually.
Several manufacturers (G.M., Volvo) have introduced this system in advance of the D.O.T. regulations as the wiring change is a simple one and the running safety benefits seem to be clear. The concept is safety via enhanced visibility to the traffic around you. The statistics seem to show that you are more quickly identifiable as a car when your halogens shine brightly at other traffic rather than relying solely on reflected light from your car body. This effect is most vital in 2 land rural highway passing when you can easily disappear into the shadow of a small hill or roadside foliage in broad daylight. The sight of your two halogen lamps is unmistakable as a CAR and could give you the additional margin of safety you need at the odd critical moment. There are also benefits when you are driving around town or on interstates or in tunnels. Think of all the plastic deer whistles sold with uncertain benefit and compare them to a free headlamp retrofit with demonstrated benefits.
The downside of this project is minor: You will be using up your $5.00 H-4 halogen insert bulbs more often and they will likely burn out sooner rather than the typical 9 years you get from them currently. (As only the headlamps are activated, there is no increased use of hard-to-change instrument cluster bulbs.) Depending upon the savvy of the motoring public you drive with, you might find some frantic waving and gesticulating to warn you about the mortal danger of running with your lights on! The fact that there is no danger of leaving them burning after you park. Your car seems little consolation to these energetic gesticulators.
For owners of BMW's and most German cars, the change to DRL is free and simple as the headlamp power is already tied to ignition switch position. For Owners of US and Japanese cars which do not tie headlamp operation to ignition power, a $9.00 Bosch relay kit is sold by the 'Lite Minder' Corp. in chain stores such as K-mart's automotive section.
I have already made the change to my families BMWs and some friend's VWs and it is a 1 hour adventure at most. Here is the step by step process:
Tools required:
Procedure:
2) Either pop out the switch body by carefully pushing and rocking from behind, or unscrew the headlamp knob and remove the locking ring, freeing the switch body from the dash.
3) Pull off the headlamp switch wiring connector and locate the 12volt wire that only activates when you turn to the IGN position. (use the volt meter function) Once you locate this wire in the responding pin on the headlamp switch at the 12V input terminal for headlamps.
4) Using the continuity feature, locate the pin which is tied to the 12V input terminal when the headlamp-on selector position is set. These two pins will likely be next to each other with no other pins intervening. You will be "strapping" these pins together with the striped wire in a figure-8. Use #15 AWG stranded wire or something close to that. You will twist the ends together to lock the strapping into place. No soldering is really needed and the wire will not take up too much space on the terminals. Be sure the wire you add does not touch any terminal pins other than the two you wish to strap together.
A somewhat more elegant alternative to the wire wrap method described is to use a 3M ScotchlokT parallel crimp-splice across the two wires in the headlamp switch power harness that correspond to the pins you detected with the multi-tester. This plastic splice has a metal knife-bridge inside the housing that you press down tight over the two parallel wires with a pliers; a plastic trap door snaps down to cover the edge of the bridge-splice.
5) Push the factory connector back in place. Turn on the car and your low beams will activate with the ignition key. Your interior lamps and tail lamps will only operate when you manually switch them on. Your high beams will be active when you manually switch them on. Your high beams will be active whenever the engine runs as they are whenever the low beams are powered.
6) Shut off the engine and put the switch back into place as well as the trim pieces removed for the installation.
This feature will use a bit more battery power while starting in cold weather, but I have heard that the headlamp drain can actually help condition your cold battery to deliver more cranking power. In any case, healthy, charged batteries should not be adversely affected by the added load.
Now that we have this issue covered, does anybody wish to suggest how best to install Anti-lock Brakes and Airbags in a 1978 320i?