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1940 Hudson Series 44 Brake Light Switch Guide

Keep your classic Hudson safe and its brake lights functioning correctly by understanding your replacement options.

3 minutes to read 1940-1940 Hudson Series 44
Difficulty
2/5
Est. Time
0.75 hrs
DIY Doable?
✅ Yes
Shop Labor
$75-$150
🚫 Do not drive — Driving without functional brake lights is extremely dangerous and illegal.
Key Takeaways
  • The 1940 Hudson Series 44 uses a hydraulic pressure switch, not a mechanical one.
  • Symptoms include lights not working, staying on, or only working with hard pedal pressure.
  • Standard Ignition is the primary aftermarket brand available and is a reliable choice.
  • Brake bleeding is required after replacement, which is a critical safety step.
On a 1940 Hudson Series 44, the brake light switch is not like the one in modern cars. It is a hydraulic pressure switch. This switch is typically mounted on the master cylinder or a nearby brake line junction. When you press the brake pedal, the pressure of the brake fluid increases. This pressure activates the switch, which closes an electrical circuit and sends power to your rear brake lights, turning them on. It's a simple and common design for vehicles from this era.

Signs of a Failing Brake Light Switch

For a vehicle from the 1940s, problems with the brake light switch are common due to age and wear. The symptoms are usually straightforward.

  • Brake Lights Don't Work: The most obvious and dangerous symptom is when your brake lights fail to illuminate when you press the brake pedal. This is a critical safety failure.
  • Brake Lights Only Work with Hard Pedal Pressure: You might find that the lights only come on if you press the brake pedal very hard. This indicates the switch is becoming less sensitive to hydraulic pressure and is about to fail completely.
  • Brake Lights Stay On: The switch can fail in the 'on' position, leaving your brake lights permanently lit. This can drain your battery and confuse other drivers.
  • Brake Fluid Leaks: Since it's a hydraulic switch, the unit itself can develop leaks over time, which can be a serious safety issue leading to loss of braking power. A switch has been reported to have blown apart, causing a fluid leak and a fire.

Choosing the Right Aftermarket Part

For a 1940 Hudson, finding a "New Old Stock" (NOS) OEM part is nearly impossible. The only practical option is a new aftermarket replacement. Fortunately, the hydraulic switches used in this era were very common across many car brands, making replacements available.

Brand Focus: Standard Ignition

Standard Ignition (also known as Standard Motor Products or SMP) is a well-known aftermarket brand that produces a compatible switch for the 1940 Hudson Series 44. Their parts are generally considered a reliable option for classic vehicles. Standard states their switches are made with brass housings for durability and use copper conductors for good electrical performance. They also mention that their design helps reduce arcing, which can extend the life of the switch. Given the limited options, a Standard Ignition switch is a solid choice for this repair.

Estimated Costs

Part Type Price Range
New Aftermarket (Standard Ignition) $15 - $20
Shop Labor $75 - $150

Installation Tip

Replacing this switch is straightforward for a DIY mechanic. It typically unscrews from the master cylinder or brake line. Crucially, after replacing the switch, you must bleed the brakes. Air will enter the hydraulic system when the old switch is removed, and it must be properly bled out to ensure your brakes work safely and effectively. If you are not comfortable bleeding brakes, this job should be left to a professional mechanic.

Frequently Asked Questions (FAQ)

Are there any recalls for the 1940 Hudson Series 44 brake light switch?

No, there are no recalls on record for this part. The National Highway Traffic Safety Administration (NHTSA) records do not typically cover vehicles of this age.

Is this a mechanical or hydraulic switch?

The 1940 Hudson Series 44 uses a hydraulic brake light switch, which is activated by the pressure of the brake fluid. This is different from the mechanical switches found on later vehicles that are activated by the movement of the brake pedal itself.

Why do my brake lights only work when I stomp on the pedal?

This is a classic sign that the internal components of your hydraulic switch are wearing out. It requires more pressure than it should to make the electrical connection. The switch should be replaced immediately, as it will likely fail completely very soon.

Can I just use any brake light switch from that era?

While many switches from the 1930s to 1960s look similar, the key is to match the thread size, which is typically 1/8-inch pipe thread, and the electrical connector type. Using a direct-fit replacement like the one from Standard Ignition (part number SLS-27) is the safest way to ensure compatibility.

Technical Specifications

Hydraulic Pressure Activated, 1/8-inch NPT (Tapered Pipe Thread)

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Meet Wrenchy → Updated Jul 21, 2026

The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.

Year Coverage
This article covers the Brake Light Switch for:
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