The Misunderstood Top Grid Lines on the BD Sedan Rear Window
Every winter, Forte drivers post photos of their rear window covered in frost, convinced that the upper section of their defroster has failed because the top three or four horizontal lines never clear the glass. Those top lines are not heating elements; they are the integrated AM/FM radio antenna grid printed onto the upper segment of the inner glass surface, sitting just above the actual heating grid. When a rock, impact, or thermal stress shatters the tempered rear window, replacing it requires matching that dual-purpose layout so your radio reception does not drop out the moment you turn on the rear defogger.
The back glass for this BD sedan carries the industry benchmark NAGS number FB27933 (often cataloged as FB27933GTN for the standard green tint). It corresponds to dealer part reference 87110-M7021, which superseded the earlier 87110-M7020 version. The glass is fixed heat-tempered safety glass framed by a wide ceramic frit band. Because there is no exterior rubber encapsulation gasket, the frit hides the bonding area while shielding the underlying adhesive from sun degradation. The perimeter borders the fixed rear quarter-light windows set into the C-pillar assembly, while the lower bottom edge meets the interior rear package tray.
Tint Film Risks, Harness Tabs, and Glass Hardware
A frequent source of electrical failure reported on forums stems from aftermarket window tinting rather than road debris. Metallic or high-density carbon tint films applied over the inner surface frequently choke out AM and FM radio signals because they blanket the integrated upper antenna grid. Worse, when an owner attempts to strip aged or bubbling tint, the aggressive adhesive pulls the delicate printed silver filaments right off the glass, severing both the radio leads and the heating circuits. Re-soldering these delicate lines or the harness terminal tabs (Kia service code 87116D3100) rarely holds up over time, making a full back glass replacement the only lasting fix.
When you book a mobile replacement, I can usually be at your location about an hour after you confirm the call, vacuuming out the shattered tempered pellets from the rear seats and package tray before setting the new glass. The vehicle utilizes factory lower alignment spacer blocks (OEM part 87114-3K000) along the bottom pinchweld ledge. These blocks ensure the replacement glass sits at the exact depth and height required so the glass line runs flush against the rear roof panel and trunk lid gap without resting directly on the steel frame.
Checking Your New Rear Glass
Once the replacement is complete and the vehicle is handed back, test the rear electrical systems and alignment before heading back out on the road:
- Turn on your AM and FM radio bands to verify crisp reception across multiple stations, confirming the upper antenna circuits are active.
- Switch on the rear defroster switch and check that all heating lines warm evenly below the antenna section, without causing static or hum over the car speakers.
- Inspect the exterior gap consistency between the top of the rear window and the roofline, as well as the lateral gaps adjacent to the fixed quarter-light panels.
- Examine the interior package tray to ensure the rear shelf trim panel sits flat beneath the glass line without rubbing or distorting the ceramic border.
- Verify that the center high-mount stop lamp (CHMSL) mounted on the rear parcel shelf has an unobstructed beam through the lower edge of the clear glass.
