We recently discovered a change by GM (and part manufacturer CASCO) in their cigarette lighter housing that could cause 1966 and older Corvettes to short out and burn their wiring harness. The change is a small bi-metal element added to the rear of the housing where the power wire connects. It was added because of the frequent use of the lighter housing to power items like CB radios, coolers, cell phones and the like. If the use is extended, the electrical thaw heat build-up should cause the bi-metal element to move, short the lighter, and blow the fuse — the intended purpose. The problem is that 1966 and older Corvettes DO NOT have a fuse for the lighter. The result of overloading a non-fused lighter is a dead short in the hot side of the harness, potentially resulting in minor to major harness damage.
The fix is very easy; simply remove the bi-metal element in the rear of the housing. This should also serve as a warning to owners of 1966 and older Corvettes to not use the lighter socket for extended periods of time, as this could cause heat buildup that could damage a wiring harness. The original GM part number for the lighter housing is 3986869, replaced by 11516142. Virtually every Corvette parts supplier uses this same housing, so any owner of a 1966 or older Corvette should check the housing and remove the bi- metal element if present.