B1587 — Autolamp Delay Increase Circuit Failure

Will B1587 clear itself?

Sometimes B1587 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What is the most common cause of B1587?

The most common causes are: corroded or loose connectors, damaged wiring in door jambs or wet areas, body control module (BCM) fault.

How much does it cost to fix B1587?

Replace the switch or actuator — $120–$450; BCM repair or replacement — $300–$900; Repair wiring or connectors — $80–$250. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What are the symptoms of B1587?

Drivers most often notice: the affected function (locks, windows, lighting, wipers) works intermittently or not at all, no impact on engine operation in most cases, warning light on the dashboard.

How do I diagnose B1587 myself?

Start with a scan: confirm B1587, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the autolamp delay increase circuit, and verify the suspect component against live data before buying parts.

When your check engine light comes on, the code stored in the vehicle's computer tells only part of the story. Code B1587 points to a fault within the body electrical system, specifically the autolamp delay increase circuit. The body control module (BCM) monitors this circuit and logs B1587 once it has confirmed the abnormality through multiple verification cycles. That verification process means the module isn't reacting to a single glitch—it has seen the problem persist under real driving conditions.

The BCM tracks the autolamp delay circuit against its factory-calibrated parameters, typically over several complete drive cycles before committing the fault to memory. At the moment B1587 sets, the module also records a freeze frame snapshot—engine RPM, load percentage, coolant temperature, and vehicle speed all captured in a single data burst. That snapshot often reveals the conditions under which the circuit failed, giving you a starting point when you hook up a scan tool. Most of the time, B1587 indicates a hardware or wiring issue within the convenience features the BCM controls, not a problem with the engine itself.

Once B1587 has been stored, the affected system may behave erratically or stop responding entirely. The nature of the failure depends entirely on which circuit the autolamp delay system shares or controls on your particular vehicle.

Symptoms of B1587

The way B1587 shows up in the driver's seat varies, but common complaints include:

• The system tied to the autolamp delay circuit stops working or works only intermittently—locks, windows, lighting, or wipers depending on your vehicle
• No effect on engine performance or transmission function in the majority of cases
• A warning light or indicator illuminated on the instrument cluster
• Unusual behavior from individual switches or controls that normally operate the affected feature
• Delayed response when attempting to activate the malfunctioning system
• In some cases, multiple body-related codes accompanying B1587

Common causes of B1587

The root cause of B1587 usually falls into one of a handful of categories. Addressing the most frequent culprits first saves time and money:

• Wiring damage in high-flex areas such as door jambs, or in locations exposed to moisture and road salt
• A failed switch, motor, or actuator within the system the BCM is monitoring
• A blown fuse or malfunctioning relay supplying power to the affected circuit
• Corroded, bent, or loose electrical connectors that interrupt the signal path
• An internal fault within the body control module itself
• Chafed wiring insulation caused by contact with sharp metal edges or heat sources

How to diagnose B1587

A methodical approach keeps you from replacing good parts. Follow these steps before ordering expensive components:

1. Connect an OBD2 scanner, confirm B1587 is present, and record all freeze frame data—this tells you exactly what the engine was doing when the fault occurred.
2. Pull every stored code, not just B1587. Related codes often expose the true root cause and must be addressed together.
3. Check manufacturer technical service bulletins for your make, model, and model year. Some B-series codes have documented software updates or known fixes that take five minutes to apply.
4. Inspect the wiring harness and connectors associated with the body electrical system. Look for damaged insulation, green or white corrosion deposits, and any wire that moves more than it should.
5. With the scanner displaying live data, operate the affected function while watching switch and motor PID values. Watch for dropped signals or values that fail to change when you activate the control.
6. Pay special attention to flex points—anywhere a wire passes through a hinge or around a moving part. Door jambs and tailgate wiring passages are the most common failure points. After repairs, clear the code, complete a full drive cycle matching the freeze frame conditions, and verify B1587 does not return.

Repair options and costs

The exact repair depends on which part has actually failed. These are typical parts-and-labor costs at independent shops in the United States:

• Switch or actuator replacement: $120–$450
• BCM repair or replacement: $300–$900
• Wiring harness or connector repair: $80–$250

Total cost to fix B1587

Most B1587 repairs involving wiring or a simple switch fall in the $80–$250 range. BCM replacement or repair pushes the total toward the higher end at $300–$900. Always confirm the root cause before buying a new module—replacing the BCM does not fix a broken wire, and a new switch does nothing if the fuse is blown.

Can you drive with B1587?

B1587 carries a short severity rating. The car will start, run, and handle normally since engine management is not affected. The main safety concerns arise only if the failure involves exterior lighting, windshield wipers during rain or snow, or central locking. In those cases, have the vehicle repaired before extended highway driving or bad weather. For comfort-feature failures alone, scheduling a repair at your convenience is reasonable.

Related OBD2 codes

• B1500: Lamp Turn Signal Left Circuit Open
• B1501: Lamp Turn Signal Left Circuit Short To Battery
• B1502: Lamp Turn Signal Left Circuit Short To Ground
• B1503: Lamp Turn Signal Right Circuit Failure
• B1504: Lamp Turn Signal Right Circuit Open
• B1505: Lamp Turn Signal Right Circuit Short To Battery