Investigation PE06012: 2004–2006 Thomas Built Buses EF

Status

CLOSED

Opened

Mar 8, 2006

Closed

Jun 15, 2006

Model years

2004–2006

Subject

Electrical panel fires

Component: Electrical system › Wiring › Fuses and circuit breakers

Summary

This investigation was opened based on four allegations of school bus fires in the power distribution module (pdm) area of the subject buses.during the investigation, odi learned thatbuses built between october 4, 2004 and february 14, 2006 were equipped with pdm?s manufactured with copper circuits that were too thin for the electrical loads encountered, creatingoverheating and thermal events.also, it was determined that multiple thermal breakers, clustered together on the pdm, together with heat generated from the pdm can generate enough heat to melt the pdm.on april 21, 2006, freightliner filed a safety recall to address this issue.freightliner's remedy is to replace all the original (thin copper circuit) pdm?s with new improved pdm?s having thicker copper circuits.also, freightliner will replace the thermal breakers with non-thermal breaker or fuses. The recall action taken by freightliner resolves the issues raised by this investigation.this investigation is closed.

An NHTSA investigation looks into whether a safety defect exists. Opening one is not a finding. Outcomes can include a recall, closure without action, or further inquiry.