INTERMITTENT STOP SIGNAL ARM

What NHTSA is examining

This investigation was prompted by complaints from two fleets alleging continuous problems with the stop arms failing during cold, wet weather.stop arms are required by federal motor vehicle safety standard, fmvss 131, school bus pedestrian safety devices.during the investigation, odi became aware of a november 2004 blue bird service bulletin addressing moisture entering the base of the stop arm and potentially preventing the stop arm from operating properly.according to the bulletin, in early 2004, the supplier of the stop arm, speciality mfr co (smc),added a heater designed to keep the microswitch contacts from freezing after the intrusion of water.on some of the early stop arms, the heater wires were not connected.field information indicated that the problem extended to other school bus final stage manufacturers.the investigation revealed the problem began in 2002 after smc changed the vendor of the microswitches and ended in early 2005 when smc again changed the switch vendor.as a result of odi?s investigation, smc has agreed to initiate a safety recall to inspect and replace the microswitches that are used internally to open and close the sign.also, smc requires that the sign be inspected for an internal heater and it?s proper installation.the proper procedure for this inspection and repair is outlined in the defect report submitted by smc.a copy of the recall is attached. Eleven final stage manufacturers have purchased the subject stop arm.all have been contacted by…

Vehicles under investigation