Chevrolet Silverado 2004–2005 — technical service bulletin
Bulletin 3134B · NHTSA communication 10010044 · issued Nov 4, 2004
Technical service bulletin
communication type
Power Train
component
2004–2005
model years
4
vehicle entries
Official summary
Service 4wd indicator illuminated. *tc with diagnostic trouble code co327. *tt
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.