Pontiac Sunbird 1989–1994 — technical service bulletin
Bulletin 438135 · NHTSA communication 37840 · issued Nov 1, 1994
Technical service bulletin
communication type
Visibility
component
1989–1994
model years
6
vehicle entries
Official summary
Buzzing sound when rear defogger is on. *tw
Vehicles covered
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.