Interpretation ID: aiam3294
Manager
Technical Legislation
International Harvester Company
2911 Meyer Road
Fort Wayne
IN 46803;
Dear Mr. Krall: This is in reply to your letter of April 30, 1980, asking whether a ne electrical switch complies with S4.5.5 of Motor Vehicle Safety Standard No. 108.; As you have described it, the switch has three positions under two o which ('IGN/ACC' and 'ACC') the hazard warning signals will operate. The third position, however, ('OFF') is a master switch which disconnects most electrical circuits on the vehicle including hazard warning signals. You have asked whether this design is permissible under S4.5.5 which requires the vehicular hazard warning signal operating unit to 'operate independently of the ignition or equivalent switch.' You have cited as precedent a 1972 letter from this agency to Imperial Fire Apparatus approving a battery disconnect switch design. In the 1972 system the hazard signals would only be activated by turning both the master switch and the flasher to 'on'. This was acceptable to NHTSA under paragraph 3(e) of SAE J910, *Hazard Warning Signal Switch*:; >>>'... providing the master switch is separate from the ignitio switch and the hazard warning signal lamps will flash with the master switch on and the ignition switch off.'<<<; The principal difference between the two systems is that your switc 'is a part of the ignition switch assembly and not physically located elsewhere on the instrument panel.'; The intent of S4.5.5 is that the hazard warning signals operat regardless whether the ignition switch is on or off.; This intent would not appear to be met by your system whose maste switch is part of the ignition switch assembly. We suggest, therefore, that you modify your design so that the hazard warning signal circuit is added to that of the 'CB' and clock which remain operable when the master switch is in the 'off' position.; Sincerely, Frank Berndt, Chief Counsel