B2531

Code

Other B — Body

Right Rear Backup Lamp Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 22 EN: 30 RU: 26

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Page language: EN

Causes

Burned out or faulty backup lamp bulb
Corroded or loose lamp socket or connector
Blown fuse or fusible link for rear lamps
Damaged wiring harness (open, short to ground or battery, chafing)
Poor or missing ground at lamp or body ground point
Faulty BCM or lamp driver transistor

Symptoms

Right rear backup lamp does not illuminate when reverse is selected
Intermittent operation of the right reverse lamp (flicker or work when tapped)
Other rear lamp circuits may be unaffected
Possible diagnostic trouble code stored and illuminated indicator depending on model

What to check

Visually inspect the right rear backup bulb and socket for damage or corrosion
Verify correct fuse(s) for rear lamps are intact
Check wiring harness and connectors for damage, corrosion, or water ingress at trunk area
Verify good body/chassis ground(s) near the lamp
Use a scan tool to confirm B2531 is current or historic and view any freeze frame data
Check left rear backup lamp operation to compare behavior

Signal parameters

Voltage at lamp socket center pin with ignition ON and transmission in Reverse: approx. battery voltage (~11–14 V)
Voltage at lamp socket with lamp removed to check feed and ground separately
Resistance of bulb filament: roughly 2–10 ohms (varies by lamp type) — open = infinite
Continuity between lamp ground pin and chassis ground: near 0 ohms
BCM output status/command from scan tool: ON/OFF or PWM duty if used

Diagnostic algorithm

Visual: Inspect bulb, socket, wiring, and connector for obvious damage, corrosion, or water.
Replace the right rear backup bulb with a known good bulb and re-check lamp operation and code. If lamp now works, clear code and verify.
Check fuses related to rear lamps and replace if blown. Re-test lamp.
With ignition ON and transmission in Reverse (use helper or apply parking brake), back-probe the lamp feed pin at the socket and measure voltage. No voltage → trace back toward connector/BCM.
Measure continuity between lamp ground pin and chassis ground. High resistance or open → repair ground.
If feed voltage is present at the socket but lamp does not light with a known-good bulb, check for poor ground or high resistance in wiring.
If no feed at socket, back-probe wiring toward the BCM/connector: look for open, short to ground, or short to battery. Wiggle wiring near hinges and splice points to reproduce intermittent faults.
If wiring and lamp are good, access BCM outputs and verify driver operation with a scan tool or service procedures. Replace BCM only after wiring and load are confirmed good.
Repair identified faults (replace bulb/socket/connector sections, repair wiring, clean/secure grounds, replace fuse, or replace BCM).
After repair, clear the DTC, cycle ignition, and verify lamp operation under several cycles and confirm code does not return.

Likely causes

Bulb filaments commonly fail — bulb out is frequent
Connector corrosion or water intrusion causing intermittent contact
Wire chafe near trunk hinge or rear quarter panel causing open or short
Ground point corrosion or loose fastener reducing current return
BCM output stage failure if wiring and lamp check good

Fault status

⚠️ Status

Right rear backup lamp circuit fault detected by BCM — possible bulb open, wiring open/short, poor ground, or BCM driver failure. Code stored; verify circuit before replacing BCM.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours