B1587

Code

Other B — Body

Autolamp Delay Increase Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 24 EN: 47 RU: 33

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Page language: EN

Causes

Open, short or high-resistance wiring in autolamp delay control circuit
Poor or corroded connector or ground at the body control module (BCM) or headlamp switch
Faulty headlamp switch, autolamp switch, or related sensor (door, ignition)
Failed relay or driver transistor used for delay timing
Faulty body control module (BCM) or lighting control module
Software/firmware issue or configuration error in BCM

Symptoms

Autolamps do not extend delay when expected or delay is fixed/incorrect
Headlamps stay on longer or turn off too quickly or inconsistently
DTC B1587 stored in body/lighting module; may be current or intermittent
Possible battery drain if lamps remain on unexpectedly
Erratic or no response from autolamp feature via dash/menu controls

What to check

Retrieve all stored/pending codes and freeze frame data with a capable scan tool
Inspect fuses and relays for the lighting/autolamp circuits
Visually inspect wiring and connectors at BCM, headlamp switch, door/ignition switches and relays
Check for corrosion, bent pins or water intrusion at connectors
Verify vehicle battery voltage (should be ~12–14 V) and battery condition
Operate door/ignition switches while monitoring BCM inputs/outputs with a scan tool

Signal parameters

Battery supply voltage to lighting module: ~11–14 V under normal conditions
Autolamp delay control output: typically a switched 12 V or ground driver (on/off) — expect logical on/off when command given
Input switch signals (door, ignition): discrete changes (0 V/12 V or signal bus message) when actuated
Ground continuity at module chassis ground: low resistance (< 1 Ω)
Module communication on vehicle data bus: module present and communicating with scan tool

Diagnostic algorithm

Connect a diagnostic scan tool and record B1587 plus any other related codes and freeze frame data.
Confirm the customer complaint by reproducing the autolamp behavior; note conditions (doors open/closed, ignition off/on, ambient light).
Visually inspect fuses, relays and related connectors for damage or corrosion; repair as needed.
Verify battery voltage and ground points. Repair any poor battery/ground condition before further testing.
With scan tool monitoring, operate the autolamp and delay-increase conditions while probing the BCM outputs and switch inputs (use backprobe or harness pinout). Look for expected state changes when delay increase is commanded.
Perform continuity and resistance checks on wiring between BCM, headlamp switch, and relevant sensors. Repair any opens/shorts.
If an external relay or driver is used for the delay function, bench-test or swap with a known-good relay to confirm operation.
If wiring and external components test good, verify BCM programming/version and update software if a service bulletin applies.
If module tests indicate an internal fault and software update does not resolve issue, consider BCM replacement per manufacturer procedure. Re-flash/configure new module as required.
Clear codes and retest to confirm repair. Monitor for reappearance or intermittent faults.

Likely causes

Wiring/connectors between BCM and autolamp switch are damaged, corroded or loose
Faulty BCM lighting driver or internal timer component
Door/ignition/hood switch stuck or not signalling properly to increase delay
Failed relay or external module used to implement delay

Fault status

⚠️ Status

Autolamp Delay Increase Circuit Failure - fault stored in body control/lighting module. Condition may be current or intermittent; autolamp delay not responding as commanded. Related inputs/outputs should be inspected.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours