B2499

Code

Other B — Body

COURTESY LAMP OUTPUT Failure

Brand: Other

Type: B — Body

Views: UK: 24 EN: 30 RU: 27

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Blown fuse for interior/courtesy lights
Failed lamp(s) (burned filament or LED failure)
Short to power or short to ground in the lamp wiring
Open circuit or high resistance in lamp wiring or connector
Faulty ground at lamp or BCM
Corroded or damaged connector pins

Symptoms

Dome/courtesy lamp(s) do not illuminate with door open or with switch
Lamp(s) stuck ON causing battery drain
Interior lights flicker or behave erratically
Related interior lighting functions (map lights, footwell) not working
Malfunction indicator or stored DTC(s) in BCM

What to check

Use a scan tool to read B2499 and any related body module codes and freeze frame data
Visual inspection of bulb(s), sockets, fuse(s) and connectors for damage or corrosion
Check fuse(s) for continuity and correct rating
Verify operation of the lamps by applying known-good 12 V to lamp connector (observe behavior)
Measure voltage at the lamp connector with circuit commanded ON and OFF
Measure resistance/continuity from BCM output pin to lamp connector and to ground

Signal parameters

Expected voltage at lamp output when ON: ~12 V (or near battery voltage) for switched + circuits; for switched-ground outputs expect ~0 V at lamp ground when ON
Expected voltage when OFF: near 0 V on switched + circuits, battery voltage on switched-ground circuits (lamp side)
Typical current: low for LED modules (
If BCM uses pulse-width modulation (PWM) expect a duty cycle signal rather than steady DC; frequency typically >100 Hz
Open-circuit: no voltage change when circuit commanded ON; short-to-ground: near 0 V with high current draw; short-to-battery: constant battery voltage with blown fuse or high module current

Diagnostic algorithm

Verify the code and any freeze frame data with a capable scan tool. Record which lamp outputs are affected and when the fault occurred.
Confirm symptom: operate dome/courtesy lamps via doors, switches, dimmer, and remote functions while observing behavior.
Visually inspect bulbs, sockets and fuses. Replace any blown fuse or burned bulb and retest.
With circuit commanded ON, measure voltage at the lamp connector. If lamp does not light but proper voltage present, suspect bulb/connector; if no voltage, proceed to wiring/BCM checks.
Disconnect the lamp assembly and check continuity/resistance from the BCM output pin to the lamp connector. Compare with wiring diagram expected values.
Check for unintended shorts: measure resistance from the output pin to chassis ground and to battery positive with circuit disconnected. Low resistance to ground indicates short to ground; low resistance to battery indicates short to battery.
Inspect and repair any damaged wiring or corroded connectors. Perform wiggle testing while observing voltage/current changes.
If wiring and lamp load check good, command the output and measure at the BCM output pin. If output is not switching or shows abnormal voltage/current, suspect BCM driver fault.
Check BCM power and ground circuits and related fuses/relays. Verify software calibration and look for Technical Service Bulletins or recalls.
If BCM is suspected faulty after all wiring and loads verified, follow manufacturer procedure for BCM replacement or reflash. After repair, clear codes and retest all functions to confirm repair.

Likely causes

Blown fuse or failed bulb(s) (easy to check)
Open or corroded connector at lamp or door jamb
Shorted wiring to battery or chassis ground
Defective BCM output driver (requires module testing/replacement)

Fault status

⚠️ Status

Courtesy lamp output circuit fault detected — output not within expected operating parameters (open, short, excessive current, or internal driver failure).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours