B2570

Code

Other B — Body

Right Lamp Outage Signal Circuit Short to Ground

Brand: Other

Type: B — Body

Views: UK: 29 EN: 31 RU: 25

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Page language: EN

Causes

Damaged or pinched wiring contacting chassis ground
Corroded or water-intruded lamp connector or socket
Faulty lamp assembly or shorted bulb (internal short or debris)
Aftermarket trailer/tow wiring or accessory improperly connected
Failed BCM or internal driver circuitry
Poor or missing ground at unrelated circuit creating backfeed

Symptoms

Right exterior lamp (tail/turn/brake depending on circuit) inoperative or intermittent
Instrument panel lamp-out or service message
Related lights behave abnormally or flash
DTC B2570 stored and possibly other body/lighting codes
Possible blown fuse if short is heavy

What to check

Use a scan tool to confirm B2570 and view freeze-frame/live data
Visually inspect right lamp, socket, and harness for damage or corrosion
Disconnect lamp connector and inspect pins for moisture, corrosion or shorts
Measure voltage at lamp connector with connector disconnected
Check resistance from signal wire to ground with ignition off
Inspect for aftermarket trailer/aux wiring splices at rear harness

Signal parameters

Expected open-circuit voltage on detection line (no short): typically near battery voltage or module pull-up (approx. 8–14 V) depending on vehicle
Short-to-ground condition: line voltage near 0–1 V
Resistance from signal wire to ground (ignition off): should be high (kΩ range); short will show near 0 Ω
Typical incandescent lamp current when on: ~0.5–2 A (varies by lamp); LEDs draw much less
Detection thresholds vary by manufacturer — consult vehicle data for exact voltages

Diagnostic algorithm

Confirm DTC with a scan tool and note any related codes and freeze-frame data.
Visually inspect the right lamp assembly, bulb/LED, socket, and harness for damage, corrosion, water, or aftermarket splices.
With ignition on, measure voltage at the lamp connector pin for the outage/detection circuit. A healthy circuit will show module pull-up voltage; a short shows ~0 V.
With ignition off, disconnect the connector and measure resistance between the signal wire and chassis ground. A near-zero reading indicates a short.
Remove the lamp/bulb/LED module and re-test the circuit. If the short clears with the lamp removed, inspect the lamp assembly for internal short or debris.
If short remains with lamp removed, trace wiring back toward the BCM, looking for chafe points, pinched wires, or aftermarket splices. Repair damaged wiring and protect with loom/tape.
Reconnect everything and clear codes. Operate lights and re-scan. If code returns, swap in a known-good lamp or connector if available to isolate cause.
If wiring and lamp check good, follow manufacturer procedures to test the BCM output/driver. Replace BCM only after wiring and lamp verified defective or per OEM guidance.
After repair, verify operation and monitor for recurrence over a drive cycle before closing repair.

Likely causes

Wiring chafe at harness routing (door hinge, trunk, bumper)
Corroded connector at lamp socket
Aftermarket connector or splice shorted to ground
Water intrusion into lamp assembly causing a short
Faulty lamp module/driver in assembly (especially for LED lamps)

Fault status

⚠️ Status

Right lamp outage signal circuit shorted to ground — BCM detects low voltage on the right lamp monitoring circuit. Lamp may be inoperative; inspect wiring and connector.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours