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Interpretation ID: nht92-9.46

DATE: January 21, 1992

FROM: William H. Spain -- Touch Wood

TO: Taylor Vinson -- Legal Counsel, NHTSA

TITLE: None

ATTACHMT: Attached to letter dated 4/27/92 from Paul J. Rice to William H. Spain (A39; Std. 108)

TEXT:

We have developed a lighting device for heavy duty trucks which may or may not fall under the purview of NHTSA statues.

We have very briefly discussed this with your Mr. Britell and Mr. Cavey, who suggested that we submit the information to you.

I am attaching a description of the device and as a separate item the way we feel the statues may or may not apply to it. Please be patient and understanding as I am not a lawyer.

I want to be clear in that we are not seeking an endorsement or even an opinion as such. We do not want to put you in the position of having to make a ruling. All we ask is your initial first impression as to whether or not we might have a problem. We have spent quite a bit of time and money on this device and are to the point of manufacture. If we have a problem then we need to stop now and back away from it. We do not intend to get into an argument over it, we will let it die first. We do however think it is a needed device that is totally in harmony with the stated purpose of 571.108 and that the device will save lives.

Realizing how very busy you must be as well as needing an indication at your earliest convenience, I have tried to keep the attached as brief as possible.

Your assistance is very much appreciated and we will be looking forward to hearing from you.

AUXILIARY LIGHTING DEVICE

As you are aware on trucks both the left and right turn signal circuits are separate from the tail lamp circuit. This device uses both the left and right turn signal circuit to act as either emergency/auxiliary tail lamps or as fog lamps. When in use neither of these new functions will interfere with normal operation of the turn signals. Each function shall be described separately.

These two new functions are controlled by a normal toggle switch mounted on the vehicle dash. In the toggle switches normal position, it is off.

It is not an uncommon occurrence for a tractor/trailer to lose its tail lamps due to a circuit or wiring malfunction. A obvious contributing factor is the constant switching of trailers between trucks. When this occurs the driver's only choice on the road is to switch on his hazard flashers which is not their intended purpose and is disconcerting to other motorists. It also defeats his normal turn signal circuits.

If our toggle switch is flipped upward to a position marked (on a nameplate) "EMERG T/LMPS", then two things happen. Firstly the center of the toggle switches lever, or paddle is illuminated and glows red. This is to remind the driver that he has something on that is not normal and to remind him to turn it off when it is no longer needed. Secondly a reduced voltage is fed through both right and left rear turn signal circuits to cause both turn signal lamps to illuminate at a reduced brilliance equal to that of a normal tail lamp. If either turn signal is activated then the full voltage is fed to that particular (left or right) lamp and the lamp flashes at its normal turn signal brilliance. To an observer the net effect is the same as normal turn signal operation (which it is).

In the event of a failure of the normal tail lamps this device provides a means of normal illumination on the vehicle's trailer and allows the driver to proceed in a safe manner to a location to have the failed, regular tail lamps repaired.

Another problem with all vehicles is reduced visibility in fog. In heavy fog the only present choice is for a motorist or trucker to activate their hazard flashers for increased rear visibility. Again this practice is disconcerting and defeats the use of normal turn signals. The European countries allow and on some trucks require a rear special fog lamp of increased brilliance for use in fog.

If our switch is flipped downward to a position marked R/FOG again two things happen. First the center of the switch will illumine red. Second a higher voltage is fed through both rear turn signal circuits to cause them to burn at approximately their full brilliance. If however either turn signal is activated then that particular (right or left) side reverts to normal turn signal operation. Therefore normal turn signal operation is not defeated.

The circuitry of our device is so configured that it automatically adjusts for the particular number of turn signal lamps on a particular truck/trailer.

STATUTES

First it shoUld be noted and considered that this device is totally in harmony with the stated purpose of 571.108.

There are obviously two directions to take in considering application of 571.108 to this device. It is very likely that 571.108 does not apply to this device. This is an auxiliary device. It does not affect those items which are required by 571.108 and auxiliary devices of this nature are not addressed by 571.108.

This device in its emergency tail lamp mode would be used only upon failure of the vehicle's regular lighting system. Its effect would be no different from the driver calling a wrecker which after hooking up would place the wrecker's own emergency tail lamps upon the rear of the towed vehicle. Obviously the wrecker's portable emergency/auxiliary tail lamps do not have to comply with 571.108 although they become the towed vehicle's tail lamps. Just as obviously they are needed on the rear of the towed vehicle on a temporary basis.

This device in its rear fog lamp mode would be two auxiliary lamps on the rear which do not interfere with normal operation of either the vehicle's normal tail lamps or turn signals. For that matter all new Jaguar automobiles imported into the U.S. come with two rear fog lamps as standard.

If however the position were to be taken that this device does fall under 571.108 then it becomes more complicated. S5.1.1.11 refers to minimum candlepower for turn signal LAMPS. This does not apply as it is common practice for manufacturers to utilize a common LAMP for both tail lamp and turn signal function. Although they do this by utilizing a dual filament bulb and dual circuits, there is no section of 571.108 requiring that this particular method be used. The net effect of our device would be identical to that of a dual filament bulb/separate circuit.

As our device does not impair the operation of any lamps required by 571.108 then we are in compliance with S5.1.3.

Whereas the normal location of rear turn signal lamps on any vehicle is assumed to be in compliance with 571.108 then these exact same lamps would also be in compliance when illuminated by our device (S5.3.1.1).

it is possible that we may have to configure our circuit in such a manner that when our switch is in the up position for emergency tail lamps it wold be on whenever the vehicle's headlamps were on. (S5.5.3).

Reference S5.5.10 (a) and when the turn signal lamps are used in conjunction with our device they are wired to flash. The lamps do not however become turn signal lamps until such time as the turn signal function is selected (by the operator). Prior to that time, the circuit, filaments, lamps, etc. can be used for other purposes as they are not turn signals until activated for that function and purpose. An example of this is the use of the turn signal circuit, filaments and lamps as stop lamps on many cars. The circuit, filaments and lamps are used in stop lamp mode until they are activated as turn signals at which time the stop lamp mode is interrupted on the appropriate side and they become turn signal lamps.