Mr. Joe Kover
463 West Creekside Lane
Kaysville, UT 84037

Dear Mr. Kover:

This responds to your letter of July 25, 1994, to Jere Medlin of this agency. You have presented several questions regarding an electric circuit that you have designed for use in motor vehicles, and which you call a Light Control Unit (LCU).

The LCU automatically turns off the headlamps and tail and parking lamps when the ignition is turned off if the lamps have been activated. The LCU also automatically turns on the headlamps and the tail and parking lamps whenever the windshield wipers are turned on. If the LCU fails when the lights are on, a Light Bus Monitor will automatically restore them.

You have the following questions:

"Would a motor vehicle operator be in violation of the federal motor vehicle safety standards by maintaining both the head and tail/park lights on during the hours of daylight?"

No. The Federal motor vehicle safety standards do not tell an owner when it is or is not permissible to use safety equipment.

"Does the LCU meet the federal motor vehicle safety standards? Could the LCU be integrated into the light system of new production vehicles or currently registered vehicles;"

The Federal motor vehicle safety standard on lighting, Standard No. 108, does not apply to supplementary lighting devices such as the LCU. The LCU is permissible on new vehicles provided it does not impair the effectiveness of lighting equipment required by the standard. We do not see that it has this effect. It is permissible to be installed on currently registered vehicles by manufacturers, distributors, dealers or motor vehicle repair businesses provided that it

does not make inoperable any part installed in accordance with a Federal motor vehicle safety standard. We do not see that the LCU has this effect either.

You have also told us that the LCU may be used to operate lamps as Daytime Running Lamps (DRLs) by maintaining the light switch in the on position when the wiper switch has been turned off. One feature of this function is that the LCU "allows the operator to turn off either the head lights only or both the head lights and tail/park lights via the light switch." Your question is "If the operator should elect to employ the LCU as a DRL unit does it meet the federal motor vehicle safety standards?"

Under Standard No. 108, a DRL system is a system of any pair of lamps on the front of a vehicle (other than parking lamps or fog lamps) that is automatically activated and that is automatically deactivated when the operator places the headlamp control in the on position. Further, DRLs can be lower beam headlamps operated at full voltage. Assuming that the LCU turns the lower beam headlamps on rather than the upper beam ones, your system would function as a DRL meeting the requirements of Standard No. 108 when the lower beam headlamps are automatically activated by the windshield wipers and deactivated by turning off the ignition. However, the feature that allows the headlamps to be turned off manually (whether or not simultaneously turning off the parking lamps and taillamps) is not part of a DRL system as specified by Standard No. 108.

Your final request is that we "include the federal specifications for electronic devices." We are unsure what you mean by this as we have no "specifications for electronic devices." I enclose a copy of S5.5.11 of Standard No. 108, the DRL specifications.


Philip R. Recht Chief Counsel

Enclosure ref:108 dL10/14/94