What Does B2550 Mean?
This code indicates the Body Control Module (BCM) has detected a short to ground in the dome/interior lamp output circuit. The BCM monitors the lamp circuit and has identified that current is flowing to ground through an unintended path, causing excessive current draw or preventing proper lamp operation. This typically means damaged wiring, a faulty lamp assembly, or a compromised BCM output driver circuit is creating a direct path to vehicle ground.
Common Causes
45%
Damaged or chafed wiring harness causing wire insulation to breach and contact body ground or metal components
30%
Failed dome lamp assembly with internal short to ground in bulb socket or housing
15%
Corroded or moisture-damaged connector terminals creating unintended ground path
10%
Failed BCM output driver transistor internally shorted to ground
Diagnostic Steps
1
Step 1: Perform visual inspection of dome lamp assembly, wiring harness, and all connectors from BCM to lamp for signs of damage, chafing, corrosion, water intrusion, or pinched wires near door jambs and hinges
2
Step 2: Disconnect dome lamp assembly connector and measure resistance between the lamp output wire (BCM side) and chassis ground using a digital multimeter - should read infinite ohms (open circuit) with lamp disconnected
3
Step 3: If short persists with lamp disconnected, systematically disconnect intermediate connectors working back toward BCM while monitoring resistance to isolate fault location in harness
4
Step 4: If no short found in wiring, reconnect harness and check dome lamp assembly by measuring resistance between lamp power pin and ground with lamp removed - should read infinite ohms or only lamp bulb resistance when switch activated
5
Step 5: If all wiring and lamp assembly test normal, suspect BCM internal fault - monitor BCM output voltage at connector with lamp disconnected using multimeter (should show battery voltage when commanded on, not zero volts indicating internal short)
6
Step 6: Clear code after repair, cycle dome lamp function multiple times using door switches and manual controls, then verify code does not return and lamp operates normally
Estimated Repair Cost
$75 - $650
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a short to ground in the dome/interior lamp output circuit. The BCM monitors the lamp circuit and has identified that current is flowing to ground through an unintended path, causing excessive current draw or preventing proper lamp opera...
The most common cause of B2550 (LAMP DOME OUTPUT Circuit Short to Ground) is: Damaged or chafed wiring harness causing wire insulation to breach and contact body ground or metal components
Typical repair costs for B2550 range from $75 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this only affects interior courtesy lighting and does not impact vehicle operation or safety systems. Repair at convenience, though lack of dome lighting may cause inconvenience during nighttime entry/exit and could drain battery if short is severe.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2550 to identify the root cause.
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Quick Info
Category
Body
System
Interior Lighting System
Difficulty
Type
Generic (SAE)
Recommended Tools
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