OBD-II Code B2590: Multi-System Fault

What Does B2590 Mean?

B2590 is a manufacturer-specific code with different definitions depending on your car. For many GM vehicles, it signals a failed left cornering lamp circuit. For Nissan and Infiniti models, it points to a communication error with the audio-visual or intelligent key system. In Ford and Chrysler vehicles, it indicates a failure in the park/speed signal circuit.

Technical definition: The SAE/ISO J2012 standard does not provide a universal definition for B2590. As a 'B' (Body) code, the vehicle manufacturer defines its meaning. Common definitions include Left Cornering Lamp Circuit Fault (General Motors, SAAB), AV Control Unit Malfunction (Nissan), ID Discord BCM-I-Key (Infiniti), and Vehicle Park/Speed Signal Circuit Failure (Ford, Chrysler).

Can I Drive With B2590?

⚠️Yes, But With Caution. Yes, but with significant caveats based on your vehicle's make. For GM lighting faults, driving is safe because primary headlights remain unaffected. For Ford/Chrysler park signal faults, the vehicle might not recognize it is in 'Park,' creating a roll-away hazard and disabling cruise control. For Nissan/Infiniti key system faults, you risk being stranded by a no-start condition. Address the underlying issue promptly to avoid safety risks.

Common Causes

• Internal Failure of Headlight Assembly (GM) (Very Common) — On many GM vehicles, moisture penetrates the sealed LED headlight unit, corroding and destroying the internal cornering lamp circuit. The entire assembly requires replacement because it is not serviceable.
• Failed Body Control Module (BCM) 🎬 See this guide on diagnosing Body Control Module issues (Nissan/Infiniti) (Common) — On Nissan and Infiniti vehicles, water intrusion from clogged sunroof drains frequently destroys the BCM. This causes a wide range of electrical failures, including key detection errors and parasitic battery drains.
• Faulty Park/Neutral Position Switch (Ford/Chrysler) (Common) — This switch tells the computer when the transmission is in Park, Reverse, Neutral, or Drive. A faulty switch sends an incorrect signal, preventing the car from starting or shifting out of gear.
• Chafed or Shorted Wiring Harness (Common) — A short or open circuit in the wiring harness disrupts the signal. This frequently occurs on GM trucks where the front fascia harness rubs against the metal bumper support, and on various makes at the exposed transmission park/neutral switch connector.
• Failed Vehicle Speed Sensor (VSS) (Less Common) — The VSS reports vehicle speed to various modules. A failure causes an erratic speedometer, harsh shifting, and disables cruise control, triggering a B2590 code as part of a 'Park/Speed Signal' fault.
• Improper Aftermarket Lighting Installation (GM) (Less Common) — Installing aftermarket HID or LED headlight bulbs in a housing not designed for them creates an electrical load or signal feedback that the BCM interprets as a fault.
• Failing Vehicle Battery or Alternator (Rare) — On electronically sensitive vehicles, low system voltage from a failing battery or alternator causes various modules to report data errors, triggering a cascade of seemingly unrelated body codes.

Symptoms

• Left Cornering Lamp Inoperative 🎬 Watch: How to replace a cornering light assembly (GM, SAAB) — The small light that illuminates the side of the road when you use your turn signal or turn the steering wheel at low speeds fails to turn on.
• No-Start or Intermittent Start (Nissan/Infiniti) — The engine cranks but does not start, or fails to crank entirely, because the BCM cannot verify the intelligent key. The security light often remains illuminated.
• Transmission Won't Shift Out of Park — The gear selector remains stuck in the Park position, even with your foot firmly on the brake pedal.
• Parasitic Battery Drain — The car battery dies overnight or after being parked for a short time. A faulty BCM fails to let other modules go to sleep, constantly drawing power.
• Engine Starts in Any Gear — A critical safety failure where the vehicle starts in Drive or Reverse, caused by a failed park/neutral safety switch.
• Cruise Control is Inoperative — The cruise control system refuses to activate because the computer cannot obtain a reliable speed signal or park status.
• Radio/Navigation Screen is Blank (Nissan) — The center infotainment screen goes blank, becomes non-responsive, or displays errors, indicating an AV Control Unit failure.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this code.

Common Fixes & Costs

• Replace Left Headlight Assembly (GM) — Parts: $400-$1500, Labor: $250-$450, ~2.5 hr book time (Intermediate)
• Replace Body Control Module (BCM) and Program Keys (Nissan/Infiniti) — Parts: $400-$900, Labor: $300-$500, ~2.2 hr book time (Professional)
• Replace Park/Neutral Position Switch — Parts: $40-$100, Labor: $150-$300, ~1.8 hr book time (Intermediate)
• Repair Chafed Wiring Harness (GM) — Parts: $10-$50, Labor: $250-$500, ~3 hr book time (Intermediate)
• Replace Vehicle Speed Sensor (VSS) — Parts: $50-$100, Labor: $125-$250, ~1.2 hr book time (DIY)

Used vs. New Parts: Buying Guide

When a used part is worth it: For GM Headlight Assemblies, a used OEM part from a low-mileage, accident-free vehicle is a cost-effective alternative to a new OEM part. For Nissan/Infiniti BCMs, a used module is viable only if you have access to a professional who programs it. For Park/Neutral Position Switches, buy new as they are inexpensive wear items.

Donor-vehicle mileage cap: roughly under 60000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• For headlights, check for clear lenses (no yellowing/fogging) and intact mounting tabs. Verify the donor vehicle did not have a front-end collision.
• For BCMs, match the part number exactly. Ensure the seller guarantees it is a functional, tested unit.
• Avoid parts from flood-damaged or rust-belt vehicles, especially for electrical components.

Decision logic:

• If The part is a Park/Neutral Position Switch → Buy new. The savings from a used part are minimal and not worth the risk of premature failure.
• If The part is a GM Headlight Assembly and budget is the primary concern → A used OEM or new aftermarket unit is acceptable. Be aware aftermarket units suffer from fitment or quality issues.
• If The part is a Nissan/Infiniti BCM → Buy new or a remanufactured unit with a warranty unless you confirmed a local specialist programs a used module to your vehicle.

Warranty tradeoff: Used parts typically have a 30-90 day warranty. Aftermarket new parts often come with a 1-year to limited lifetime warranty. New OEM parts carry a 1-2 year warranty.

Worst-case if a used part fails: $300-$800 if a used part fails after installation, primarily due to repeat labor costs and purchasing another part.

What Happens If You Wait — Timeline

1. 0-1 month: Nissan/Infiniti: Intermittent no-start or key-not-detected warnings, especially during rain. B2590 code is set. No other major symptoms yet. (MPG impact: 0%% · Added cost: $0)
2. 1-3 months: The water-damaged BCM fails intermittently, not going to 'sleep' properly. This causes a parasitic battery drain. The owner finds the battery dead after parking for a day or two. (MPG impact: 0%% · Added cost: $50-$100 in wasted time, jump starts, or a tow.)
3. 3-6 months: The chronic parasitic drain and repeated deep cycling destroys the vehicle's main 12V battery. The BCM fault is constant, and the car is unreliable. The water leak continues, further damaging connectors. (MPG impact: 0%% · Added cost: $200-$400 for a new battery, which is also damaged if the root cause isn't fixed.)
4. 6+ months: Catastrophic failure. The BCM is completely non-functional. The car does not start. The constant low voltage from the bad battery and drain puts extreme strain on the alternator, shortening its life. Repair requires a new BCM, battery, and potentially an alternator. (MPG impact: N/A (Vehicle is undrivable)% · Added cost: $2,250+ in cascading component failures.)

Cost of Not Fixing It

• Immediate: GM: Reduced visibility when turning. Ford/Chrysler: Inability to shift from Park, inoperative cruise control, or potential for vehicle rollaway. Nissan/Infiniti: Inability to start the vehicle, getting stranded. (Added cost: Negligible compared to the cost of a tow.)
• 1-3 months: Nissan/Infiniti with BCM fault: Persistent parasitic battery drain destroys the vehicle's battery, requiring replacement. Ford/Chrysler: Continued stress on the shift interlock solenoid if the park signal is intermittent. (Added cost: $150-$400 for a new battery and potential labor.)
• 6+ months: A chronic parasitic drain puts extreme strain on the alternator, shortening its life. A vehicle that starts in any gear (due to a failed park/neutral switch) is a major safety hazard that causes accidents. (Added cost: $500-$1000+ for a new alternator or accident-related costs.)

Diagnosis Steps

1. Identify Your Vehicle's B2590 Definition
   Use a professional scan tool to pull the manufacturer-specific definition. If unavailable, search online for '[Your Car Make/Model/Year] B2590 code' to determine if it relates to lighting, park/speed signals, or the BCM/key system.
   Tools: OBD-II Scanner (capable of reading B-codes) (Beginner)
2. Perform a Focused Visual Inspection
   For GM, check the left headlight for moisture, fogging, or pooled water. For Ford/Chrysler, inspect the wiring and connector at the Park/Neutral Position Switch on the transmission. For Nissan/Infiniti, check for water intrusion or stained carpets near the BCM in the passenger footwell.
   Tools: Flashlight (Beginner)
3. Test the Specific Symptom
   For GM, turn on the low beams, activate the left turn signal, and check the cornering lamp. For park/speed issues, verify if you can shift out of park. For Nissan/Infiniti, attempt the emergency key fob start procedure by holding the fob directly against the start button.
   Tools: None (Beginner)
4. Check Fuses and Relays
   Consult your owner's manual to locate and inspect fuses related to the Body Control Module, lighting modules, and transmission controls. Replace any blown fuses.
   Tools: Fuse puller or needle-nose pliers (Beginner)
5. Pro Tip: Test Circuit Voltage and Ground (GM Lighting)
   Disconnect the left headlight connector. Using a multimeter, check for 12V power at the cornering lamp pin when the function is active (low beams on, left turn signal on). If 12V and a good ground (<0.5 ohms) are present, the headlight assembly has failed internally. If no voltage is present, the problem lies in the wiring or BCM.
   Tools: Multimeter, Vehicle-specific wiring diagram (Intermediate)
6. Pro Tip: Test Park/Neutral Position Switch Signal (Ford/Chrysler)
   Using a scan tool with live data, monitor the Transmission Range Sensor PIDs (TR_V and TR_STATE) while cycling the shifter through all gears. The TR_STATE must match the shifter position. The voltage (TR_V) should change predictably (e.g., Park ~3.4V, Reverse ~3.0V, Neutral ~2.5V, Drive ~1.5V). A stuck, erratic, 0V, or 5V reading indicates a failed sensor or circuit.
   Tools: Advanced Scan Tool with Live Data, Multimeter (Advanced)
7. Diagnose BCM (Nissan/Infiniti) 🎬 Watch: What you need to do when replacing a Nissan BCM
   Check for water damage around the BCM. Use a professional scan tool (like Nissan CONSULT) to check for communication errors with the BCM and Intelligent Key module. If communication fails but power/ground to the BCM are good (>12V on power pins, <0.5 ohms on ground pins), the BCM requires replacement.
   Tools: Professional scan tool, Multimeter (Advanced)
8. Pro Tip: Check CAN Bus Resistance
   If multiple communication codes (U-codes) accompany B2590, disconnect the battery. Measure resistance between Pin 6 (CAN High) and Pin 14 (CAN Low) on the OBD-II port. A healthy network reads ~60 ohms. A reading of 120 ohms means a terminating resistor is offline. An open or shorted reading points to a wiring fault.
   Tools: Multimeter (Advanced)

When This Code Triggers (Freeze-Frame Conditions)

• System Voltage: 11.5V - 14.5V (Code sets with low voltage during cranking (Nissan/Infiniti) or normal operating voltage (GM/Ford).)
• Vehicle Speed: 0 mph (Fault detected during startup (Nissan/Infiniti key system) or when shifting out of Park (Ford/Chrysler).)
• Component Status: Active/On (For GM, the code sets when the BCM commands the left cornering lamp ON but detects an open or short circuit.)
• Gear Selector Position: Park (For Ford/Chrysler, the fault is logged when the BCM receives an invalid or missing 'Park' signal from the transmission range sensor.)

Related Codes

• B2595 — The identical code for the right side ('Right Cornering Lamp Circuit'). If both B2590 and B2595 are present, suspect a shared power/ground issue, a chafed wiring harness, or a faulty BCM, rather than two simultaneous headlight failures.
• P0705 — This generic code for 'Transmission Range Sensor Circuit Malfunction' often appears with the 'Vehicle Park/Speed Signal Circuit Failure' version of B2590 on Ford/Chrysler vehicles. Diagnosing P0705 typically leads to the same repair.
• U1000 / U0100 — Communication codes indicating a loss of communication with a module. On Nissan/Infiniti, diagnose these 'U' codes first. B2590 is a symptom of the U-code; fixing the communication problem resolves the B2590.
• B2575 — A GM code for 'Headlamp Control Module' faults. If B2590 appears alongside B2575 and other communication codes, it strongly suggests a wider electrical issue like front fascia wiring harness chafing.

Climate & Environmental Factors

• High Humidity / Heavy Rain: Strongly contributes to GM headlight failures by promoting moisture ingress into the sealed assembly. Also worsens Nissan/Infiniti BCM failures by overwhelming clogged sunroof drains, causing water to leak directly onto the module.
• Cold Climates / Road Salt: Accelerates corrosion of the Park/Neutral Position Switch and its electrical connector on Ford/Chrysler vehicles, as the switch is exposed on the transmission housing. This corrosion disrupts the signal.

How to Talk to a Mechanic About This Code

Say this: "I have a B2590 code on my [Make, Model, Year] and I need a diagnostic. Based on my research, for this car it likely means [select one: 'a failed cornering lamp in the headlight', 'a bad park/neutral switch on the transmission', 'a faulty BCM due to a water leak']. Can you please start your diagnosis there?"

This immediately signals you are an informed customer. It guides the technician toward the most likely cause, saving diagnostic time, and prevents them from starting with expensive, unlikely theories. It frames the conversation around a specific, known issue for your vehicle type.

Avoid saying:

• 'My check engine light is on, can you look at it?' (This code doesn't usually turn on the check engine light and is too vague).
• 'Just fix whatever is wrong.' (This is an open invitation for unnecessary repairs and up-selling).
• 'My car won't start, I think it's the battery.' (While it could be, on a Nissan/Infiniti with this code, the bad BCM is what kills the battery; replacing only the battery won't fix it).

Questions to ask before authorizing the repair:

• For GM: Did you see moisture in the headlight or find chafed wires on the front harness? Please confirm before we order a new headlight assembly.
• For Nissan/Infiniti: Did you find evidence of a water leak near the BCM? Can you confirm you have the tools to program a new BCM to my keys and VIN?
• For Ford/Chrysler: Did you test the Transmission Range Sensor signal? Can you show me the live data from the scan tool?
• What is the warranty on the recommended part and your labor?

Where to Take It: Dealer vs Independent vs Chain

• Dealer: Required for Nissan/Infiniti BCM replacement. A safe, but expensive, choice for other variants.
  Best for: Nissan/Infiniti BCM replacement, as they have the required CONSULT diagnostic tool for programming., Vehicles still under warranty., Complex electrical issues on GM vehicles where multiple codes are present with B2590.
  Downsides: Highest labor rates., Defaults to expensive OEM parts when quality aftermarket options exist (e.g., GM headlights). (Typical cost: +50% vs. baseline)
• Independent Shop: Excellent choice for the Ford/Chrysler and GM versions of this code, provided the shop is well-equipped. For Nissan/Infiniti, only use a specialist who proves they can program a new BCM.
  Best for: Ford/Chrysler park/neutral switch replacement., GM headlight assembly replacement, especially if you want to use aftermarket parts., Shops specializing in your car's brand (e.g., a trusted Japanese auto repair shop for a Nissan).
  Downsides: Must verify they have advanced diagnostic tools capable of reading manufacturer-specific 'B' codes., Most independent shops cannot program a new Nissan/Infiniti BCM. (Typical cost: +0% vs. baseline)
• Chain Shop: AVOID. The complexity and brand-specific nature of B2590 make a misdiagnosis and incorrect repair highly likely.
  Best for: None. This code is not suitable for a chain shop.
  Downsides: Technicians are unlikely to be familiar with the manufacturer-specific nature of this code., High risk of misdiagnosis (e.g., selling you a BCM for a GM vehicle when the headlight is the problem)., Lack of advanced, brand-specific diagnostic and programming tools. (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If the total estimated repair cost exceeds 50% of the car's private-party market value, pause and seriously consider alternatives to repair.

• Car worth $15000, fix is $2200: Fix it. A $2,200 repair for a GM headlight or Nissan BCM is significant, but well below the 50% threshold on a $15,000 truck or SUV.
• Car worth $7000, fix is $1900: Borderline - Get a second opinion. A nearly $2,000 repair on a $7,000 car approaches 30% of its value. Ensure the diagnosis is correct before proceeding.
• Car worth $4000, fix is $2500: Walk away. The repair cost is over 60% of the car's value. It is not financially sensible to perform this repair.

What Scan Tool You Need for This Code

Minimum: A scanner that reads manufacturer-specific Body Control Module (BCM) codes. A generic $20 reader that only pulls 'P' codes is useless for B2590.

A basic code reader shows 'No Codes' or fails to give the specific definition. You MUST know if your GM vehicle has a 'Left Cornering Lamp' fault or if your Nissan has an 'ID Discord' fault. Without this, you cannot diagnose the problem.

Budget: BlueDriver Pro or Autel AP200 (~$100) — These Bluetooth dongle-style scanners connect to your smartphone and read codes from all modules, including the BCM. This gives you the crucial manufacturer-specific definition of B2590.

Mid-range: Autel MaxiCOM MK808S or Launch CRP129E (~$350) — Provides the specific code definition and allows you to view live data streams. This is critical for diagnosing the Ford/Chrysler variant by watching the Transmission Range Sensor data as you move the shifter.

Professional: Autel MaxiSys Series or Launch X431 Series (~$800-1500) — These professional-grade tools offer full bidirectional control to test components directly (e.g., command the GM cornering lamp on/off). Crucially, they have the advanced programming functions required to replace and program a new BCM on a Nissan or Infiniti.

Rent vs buy: For a one-time diagnosis, a budget pick like BlueDriver is a worthwhile investment. If you have the Nissan/Infiniti variant, no rentable or cheap tool programs the BCM, requiring a shop with a pro-level tool.

How to Clear the Code After You Fix It

1. Use an OBD-II scan tool to clear the code.
2. For GM lighting faults, perform a hard reset by disconnecting the negative battery cable for at least 60 seconds.
3. For Nissan/Infiniti BCM replacement, program the new BCM and re-register all keys using a compatible scan tool.
4. Perform a functional test of the repaired system (e.g., activate cornering lamp, shift through gears, start the engine).

Drive cycle (~10 minutes): A formal drive cycle is not required for this body code. The BCM re-evaluates the circuit status upon the next key cycle or component activation. For GM, a battery disconnect is mandatory to unlatch the circuit. For other makes, clearing the code with a scanner is sufficient.

Watch out for:

• Forgetting to disconnect the battery after a GM headlight replacement, causing the new part to remain inactive and the code to persist.
• Attempting to install a used Nissan/Infiniti BCM without the ability to program it, resulting in a permanent no-start condition.
• Clearing the code without addressing the root cause (e.g., water leak, chafed wiring), leading to the code's immediate return.

Will This Fail Emissions / State Inspection?

No — by itself this code doesn't fail OBD inspection (but it can keep readiness monitors from setting, which causes a separate fail).

• California: A 'B' code like B2590 does not cause a smog check failure. California's test focuses on emissions-related 'P' codes and readiness monitor status.
• New York: The NYVIP3 inspection primarily checks for illuminated MIL (Check Engine Light) and emissions-related codes. A B-code does not cause an emissions failure, but an inspector fails the safety inspection for an inoperative lamp if deemed part of required lighting equipment.
• Texas: As of 2025, annual safety inspections are eliminated for most non-commercial vehicles in Texas. Emissions testing is still required in 17 counties, but a B-code does not trigger a failure.

Most Commonly Affected Vehicles

• Cadillac Escalade, Escalade ESV (2015-2020) — Prone to the 'Left Cornering Lamp Fault' due to moisture in the LED headlights. TSB #PIT5487F notes that a chafing front bumper harness causes this and other lighting codes.
• Chevrolet Silverado, Suburban, Tahoe (2014-2019) — These models share the K2XX platform with Cadillac and experience identical cornering lamp failures from moisture and wiring harness chafing.
• GMC Sierra, Yukon, Yukon XL (2014-2019) — Highly susceptible to the B2590 cornering lamp fault. The repair procedure is identical to the Chevrolet and Cadillac models.
• Infiniti G37, Q50, FX35 (2008-2017) — Known for BCM failures ('ID Discord BCM-I-Key') caused by water leaks from clogged sunroof drains located in the A-pillars, allowing water to drip onto the BCM.
• Nissan Armada, Altima, Rogue (2009-2017) — Suffer from BCM failures (B2590 'ID Discord') or AV Control Unit failures. The 2013-2017 Altima is particularly notorious for BCM water damage.
• Ford Focus, Fusion, E-Series (2008-2016) — B2590 typically means 'Vehicle Park/Speed Signal Circuit Failure', traced back to a faulty Transmission Range Sensor (Park/Neutral Switch).
• Dodge / Chrysler Grand Caravan, Town & Country (2008-2016) — Commonly sets B2590 for 'Vehicle Park/Speed Signal Circuit Failure', preventing shifting out of park due to a corroded park/neutral position switch.
• SAAB 9-5 (2010-2011) — Defines B2590 as 'Left Cornering Lamp Circuit Open' or 'Short to Ground', a fault nearly identical to the GM definition.

Manufacturer-Specific Notes

• General Motors: The BCM 'latches' the cornering lamp circuit off after detecting a fault. After replacing the headlight, you must perform a hard reset by disconnecting the negative battery cable for at least 60 seconds, otherwise the new part will not function.
• Nissan / Infiniti: A replacement BCM is never plug-and-play. It requires programming with a dealer-level scan tool (CONSULT) to register the vehicle's VIN and keys. Failure to do this results in a permanent no-start condition.
• SAAB: On models like the 9-5 (2010-2011), the cornering lamps have a 'park function' where both turn on when the vehicle is in reverse, providing an alternative way to test lamp functionality.
• Ford: For 2011-2016 Fiesta and 2012-2016 Focus models with the DPS6 automatic transmission, a failing Transmission Control Module (TCM) causes related park/neutral signal issues, often covered under extended warranty programs.

Real Owner Stories

2015 GMC Sierra 1500 at 110K miles - Cornering Lamp Failure

Owner received a 'Left Cornering Lamp Failure' message on the dash display and code B2590. The cornering light was confirmed inoperative.

Outcome: Replaced the entire left headlight assembly with an aftermarket part for ~$500. The B2590 code returned immediately. After searching forums, they performed a hard reset by disconnecting the battery for 5 minutes, clearing the 'latched' BCM fault. The new light then worked correctly.

Lesson: For GM cornering lamp faults, the BCM latches the circuit off. After replacing the headlight, you must perform a hard reset by disconnecting the battery to make the new part work.

2013 Infiniti G37 at 85K miles - Misdiagnosis and BCM Failure

Car experienced intermittent no-start issues, random alarm activation, and a parasitic battery drain killing the battery in two days. Code B2590 ('ID Discord BCM-I-Key') was present alongside communication code U1000.

Outcome: An Infiniti specialist immediately suspected a water-damaged BCM. The passenger-side carpet was damp, and the BCM showed corrosion. The specialist traced the leak to a clogged sunroof drain. The fix required replacing and programming the BCM, costing over $1,800.

Lesson: On Nissan/Infiniti vehicles, B2590 accompanied by U-codes and parasitic drain is almost always a faulty BCM due to water leaks. Diagnose U-codes first and check for water intrusion before replacing other parts.

2012 Ford Focus at 95K miles - Easy Fix, Difficult Access

The vehicle would not shift out of Park, and the cruise control was inoperative. The owner scanned the vehicle and found codes B2590 and P0705.

Outcome: The owner purchased a new Motorcraft sensor for $60. The repair was straightforward but took two hours due to the sensor's tight location on the side of the transmission, requiring airbox removal. After replacement and clearing codes, the vehicle shifted normally. Total cost was under $100.

Lesson: For Ford 'Park/Speed Signal' faults, the Transmission Range Sensor is a common and inexpensive part to fail. Be prepared for difficult access that makes the DIY repair time-consuming.

How to Prevent This Code From Triggering

• Clean sunroof drains (Nissan/Infiniti) (Every 1-2 years, or annually in leafy/dusty areas) — Prevents the primary cause of BCM failure. Drains clog with debris, causing rainwater to overflow from the A-pillar and drip directly onto the BCM in the passenger footwell. Use compressed air or flexible nylon wire to clear them.
• Apply dielectric grease to the Transmission Range Sensor connector (Ford/Chrysler) (Once, or whenever working near the transmission) — The sensor and its connector are exposed to road spray and salt, causing corrosion and signal failure. Applying dielectric grease seals out moisture and prevents corrosion, extending connection life.
• Inspect and protect front wiring harness (GM K2XX Trucks) (Once, during other front-end service (e.g., bulb change)) — TSB #PIT5487F identifies a spot where the front fascia harness rubs against a metal bumper support. Over time, chafing wears through the insulation, causing shorts that trigger B2590. Wrap the harness in protective conduit or tape.
• Maintain a healthy battery and charging system (Ongoing) — On modern, electronically-sensitive vehicles, low system voltage during startup causes modules to report spurious communication errors, including B2590 and U-codes. A fully charged battery prevents these voltage drops.

Frequently Asked Questions

Can I just replace the cornering light bulb on my Chevy/GMC?

No. On most modern GM trucks and SUVs (2014+) with this code, the cornering lamp is an LED permanently integrated into the sealed headlight assembly. You must replace the entire unit.

Why did my car battery die overnight after getting a B2590 code?

A dead battery is a classic symptom of a faulty Body Control Module (BCM), common on Nissan and Infiniti vehicles. The failing BCM does not shut down properly, causing a parasitic drain that kills the battery.

I replaced the GM headlight but the B2590 code is still there. What's wrong?

The GM Body Control Module (BCM) latches the circuit off to protect it. After installing the new headlight, you must disconnect the negative battery terminal for at least 60 seconds to force the BCM to reset.

What are the most common misdiagnosis mistakes for B2590?

The biggest mistake is trusting a generic code definition instead of the manufacturer-specific one. For example, replacing a transmission sensor on a Cadillac when the code actually means 'Left Cornering Lamp.'

Can I use a cheaper aftermarket headlight assembly for my GM truck?

Yes, aftermarket assemblies are significantly cheaper than OEM parts. However, fit, finish, and the long-term reliability of the internal electronics are often inferior.

Can I replace the BCM myself to save money?

You can physically swap the module, but the car will not start. A new BCM must be professionally programmed to match your car's VIN and security keys using specialized dealer-level software.

Is it safe to drive with a B2590 code?

Yes, but with caution depending on your vehicle. A GM cornering light failure is a minor visibility issue, but a Ford park signal fault creates a roll-away hazard. A Nissan BCM fault risks stranding you with a no-start condition.

What is the difference between a BCM and an ECM?

The BCM (Body Control Module) manages body electronics like lights, windows, and anti-theft systems. The ECM (Engine Control Module) manages the engine and transmission. B2590 is a 'B' code originating from the BCM.

Key Takeaways

• Verify your vehicle's specific B2590 definition before buying parts, as this code means 'Left Cornering Lamp Failure' on a 2015 GMC but 'Park Signal Failure' on a 2012 Ford.
• For 2014+ GM trucks and SUVs, fixing B2590 requires replacing the entire sealed headlight assembly ($400-$1,500) and disconnecting the battery for 60 seconds to reset the BCM.
• On Nissan and Infiniti models, B2590 usually indicates a water-damaged Body Control Module (BCM) caused by clogged sunroof drains, requiring a $700+ replacement and dealer programming.
• For Ford and Chrysler vehicles experiencing a no-shift-from-park condition with this code, test the Transmission Range Sensor using a multimeter to verify voltage changes across gear positions.