AutoCodes – Generic – B1509

B1509 Code - Flash To Pass Switch Circuit Short To Battery

Quick Answer

The Smart Junction Box (SJB) sends reference signals to the headlamp switch through circuits. Common causes include Faulty Headlamp Switch, Headlamp Switch harness is open or shorted, Headlamp Switch circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: B1509 indicates Flash To Pass Switch Circuit Short To Battery.
Common causes: Common causes include Faulty Headlamp Switch, Headlamp Switch harness is open or shorted, Headlamp Switch circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 7,781

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 29, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B1509 Description

The Smart Junction Box (SJB) sends reference signals to the headlamp switch through circuits. When the headlamp switch is placed in the HEADLAMPS ON position, the voltage signal is routed to ground through the circuit. If the SJB detects a fault with the headlamp switch inputs, the SJB turns the exterior lamps on by default. When the SJB detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the LOW BEAM position, the SJB sends voltage through circuits to the low beam headlamps. When the SJB detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the HIGH BEAM position, the SJB sends voltage through circuits to the high beam headlamps. The SJB sends a reference signal to the multifunction switch through circuits CLF27 (GN/BN) and CLF17 (WH/OG). When the multifunction switch is placed in the FLASH-TO-PASS or HIGH BEAM position, the voltage signal is routed to ground. When the SJB detects a request for the flash-to-pass, the SJB sends voltage to the high beam headlamps. The OBDII codes when the SJB detects a short to ground from the flash-to-pass input circuit.

OBDII Code B1509 - Flash To Pass Switch Circuit Short To Battery - AutoCodes.com — B1509 Code - Flash To Pass Switch Circuit Short To Battery

What does this mean?

What are the Possible Causes of the DTC B1509?

Faulty Headlamp Switch
Headlamp Switch harness is open or shorted
Headlamp Switch circuit poor electrical connection
Faulty Smart Junction Box (SJB)

How to Fix the DTC B1509?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B1509 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the B1509 code?

Need more information on how to fix the B1509 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B1509 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B1509 Ford — Flash To Pass Switch Circuit Short To Battery
B1509 Lincoln — Flash To Pass Switch Circuit Short To Battery
B1509 Mercury — Flash To Pass Switch Circuit Short To Battery

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B1509 Code

1. What are the common symptoms of OBDII code B1509 (Flash To Pass Switch Circuit Short To Battery)?

The common symptoms include the inability to activate the flash-to-pass feature, malfunctioning high beam headlights, and the illumination of the check engine light.

2. What can cause the OBDII code B1509 to trigger?

This code is typically triggered by a short circuit between the flash-to-pass switch circuit and the battery, which disrupts the proper functioning of the system.

3. How can I diagnose the Flash To Pass Switch Circuit Short To Battery issue?

Diagnosing this issue involves inspecting the wiring harness for any visible damage, checking for short circuits with a multimeter, and testing the flash-to-pass switch for proper functionality.

4. Can I still drive my vehicle with the B1509 OBDII code?

While it may be safe to drive your vehicle with this code, it is recommended to address the issue promptly to ensure the proper functioning of the flash-to-pass system.

5. How can I repair the Flash To Pass Switch Circuit Short To Battery problem?

Repairing this issue involves repairing or replacing any damaged wiring, fixing the short circuit, and potentially replacing the flash-to-pass switch if necessary.

6. Are there any DIY tips for fixing the Flash To Pass Switch Circuit Short To Battery fault?

If you have experience with automotive wiring, you may attempt to locate and repair the short circuit yourself. However, if you are unsure, it is best to seek professional help to avoid causing further damage.

7. Will resetting the OBDII code B1509 make the issue go away?

Resetting the code may temporarily turn off the check engine light, but it will not fix the underlying problem causing the Flash To Pass Switch Circuit Short To Battery fault.

8. How much does it typically cost to repair the B1509 OBDII code?

The cost of repairing this code can vary depending on the extent of the damage and whether any components need to be replaced. It is advisable to consult a mechanic for an accurate estimate.

9. Is the Flash To Pass Switch Circuit Short To Battery issue common in specific vehicle makes and models?

While this issue can occur in various vehicles equipped with a flash-to-pass feature, it may be more common in certain models that use similar wiring configurations.

10. Can extreme weather conditions contribute to triggering the B1509 code?

Yes, extreme weather conditions such as water exposure or extreme temperatures can potentially damage the wiring harness and lead to a short circuit, triggering the B1509 code.