What does it mean?
B2508 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Telltale Lamp circuit Fault .
Symptoms
- The right high beam stays on regardless of the stalk position
- The main beam indicator stays lit on the cluster
- Oncoming drivers flash because the beam cannot be switched off
- The module disables the output and the right high beam stops working altogether
- Battery discharge when the vehicle is left parked
Likely causes
- High beam wire for the right headlamp contacting a live circuit inside the front loom
- Moisture and corrosion linking the high beam pin to an adjacent powered pin in the headlamp connector
- Auxiliary driving lamp or light bar wired into the right high beam feed
- Loom crushed or pierced during headlamp, grille or bumper work
- Relay with welded contacts feeding the lamp continuously
- Conversion bulb driver back feeding voltage onto the control line
- Lighting module output driver failed in the closed state
How to fix it
- With main beam off, measure for voltage at the right high beam output at the module connector
- Unplug the headlamp and repeat the measurement; voltage still present points to the harness rather than the lamp
- Where a relay is used, remove it and see whether the voltage disappears, which identifies welded contacts
- Inspect the headlamp connector for corrosion bridging the high beam pin to a supply pin
- Disconnect any auxiliary lamps or light bars wired into this circuit and retest
- Trace and repair the shorted section of loom, then reroute and protect it properly
- Replace the relay, the harness section or the lighting module according to where the unwanted voltage originates