What does it mean?
B2517 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Internal Tail Lamp Circuit Short to Ground .
Symptoms
- Inner tail lamp section stays dark while the outer lamp still lights, or the reverse
- Fuse for rear lighting blows, often taking the number plate lights with it
- Lamp outage message that appears or clears when the trunk lid is moved
- Rear lights flicker while the lid is opened and closed
- Water or condensation visible in the lamp mounted on the lid
- Code returns after clearing whenever the lights are switched on
Likely causes
- Wiring fatigue and broken strands inside the flexible loom that crosses the trunk lid or tailgate hinge
- Water leaking past the tailgate seal into the inner lamp housing and filling the socket
- Corroded bulb socket contact collapsing onto the metal shell
- Chafed harness where it passes through the rubber grommet between body and lid
- Rear harness crushed by cargo or after a rear collision repair
- Non-original wiring for a camera, spoiler light or trailer socket tapped into the inner lamp circuit
- Failed output driver in the rear or body control module
How to fix it
- Open the trunk lid and inspect the flexible harness at the hinge; peel back the loom sleeve to look for cracked insulation and broken wires
- Remove the inner lamp assembly and check for water, corrosion and a socket contact shorted to its shell
- Unplug the lamp and measure from the feed wire to ground to determine which side of the connector is shorted
- Move the harness through its full range while monitoring resistance to catch an intermittent short
- Disconnect trailer or accessory wiring spliced into this circuit and retest
- Repair the flexible section with stranded wire and heat-shrink, keeping enough slack for the lid to open
- Reseal the housing and grommet, then verify the repair with the lamps on and the lid cycled several times