B2550: Courtesy Lamp Circuit Short to Ground
The Body Control Module (BCM) has detected a short to ground in the output circuit that powers the courtesy lamps (dome/map lights). This indicates that the wiring, connector, or lamp assembly has abnormally low resistance to chassis ground, preventing proper interior lighting control and protecting the module from overcurrent.
1. Commonly Affected Makes
2. Most Common Causes
- Chafed or pinched wiring in the dome lamp circuit contacting chassis ground
- Internal short circuit in the courtesy lamp bulb or LED assembly
- Corrosion or moisture bridging terminals at the lamp connector or BCM connector
- Failed output driver inside the Body Control Module
3. Symptoms You Will Notice
- Interior courtesy lamps inoperative or always on
- BCM may disable the circuit to prevent damage
4. Step-by-Step Diagnosis
Visually inspect dome lamp wiring for chafing or pinching against metal surfaces
Remove the lamp assembly and test for short to ground at the connector using a multimeter
Check BCM connector for corrosion or bent pins
If wiring and lamp are good, suspect internal BCM failure and perform module test
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive, but interior lights may not work properly. The BCM protects itself by disabling the circuit, so no immediate safety risk exists.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether the issue is a simple wiring repair or requires BCM replacement and programming.