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1959 Studebaker 4E12 Brake Light Switch Location and Replacement

Understanding the simple but critical hydraulic brake light switch in your classic Studebaker truck.

3 minutes to read 1959-1959 Studebaker 4E12
Difficulty
1/5
Est. Time
0.5 hrs
DIY Doable?
✅ Yes
Shop Labor
$50-$100
Used OEM Price
$10-$30
🚫 Do not drive — It is illegal and extremely unsafe to drive a vehicle with non-functioning brake lights.
Key Takeaways
  • The 1959 Studebaker 4E12 uses a hydraulic pressure switch on the master cylinder, not a mechanical switch by the pedal.
  • Failure of this switch is a critical safety issue; do not drive the vehicle if the brake lights are not working.
  • A new aftermarket switch from Standard Ignition is the most practical and available replacement part.
  • Replacement is an easy DIY task, but you should be prepared to bleed the brakes afterward to ensure safety.
Unlike modern vehicles, your 1959 Studebaker 4E12 does not use a mechanical switch at the brake pedal. Instead, it uses a hydraulic pressure switch that is screwed directly into the brake master cylinder. When you press the brake pedal, the building fluid pressure activates the switch. This action completes the electrical circuit, sending power to your rear brake lights and signaling to other drivers that you are slowing or stopping. Because of its design, this switch is a critical component for both the brake system and electrical system.

Is Your Brake Light Switch Failing?

A faulty brake light switch is a major safety hazard. On a classic truck like the 1959 Studebaker 4E12, the original-style hydraulic pressure switches are a common point of failure. They can wear out over time, leading to dangerous situations on the road. Recognizing the symptoms early is key to staying safe.

Common Symptoms of a Bad Switch

  • Brake Lights Don't Turn On: This is the most common and dangerous symptom. The internal contacts of the switch wear out and no longer complete the circuit.
  • Brake Lights Only Work with Hard Braking: The switch may require excessive hydraulic pressure to activate, meaning your lights won't come on during gentle stops.
  • Brake Lights Stay On: The switch can fail in the 'on' position, leaving the brake lights permanently illuminated. This can drain your battery and confuse other drivers.
  • Brake Fluid Leak: Since the switch is part of the hydraulic system, a crack in its housing or a bad seal can cause a brake fluid leak at the master cylinder.

Safety First: A Critical Part

Driving without functional brake lights is illegal and extremely dangerous. If you suspect your brake light switch has failed, you should not drive the vehicle until it is repaired.

Choosing the Right Aftermarket Part

For the 1959 Studebaker 4E12, finding original "New Old Stock" (NOS) parts is nearly impossible. Fortunately, the aftermarket provides a reliable solution.

The Aftermarket Solution: Standard Ignition

Standard Ignition (also known as Standard Motor Products) is a well-established brand that produces a direct replacement hydraulic brake light switch for your truck. This part is designed to match the specifications of the original, including the 1/8-NPT thread for screwing into the master cylinder. It serves as a reliable and cost-effective replacement for a failed original switch.

Pro Tip: The Mechanical Switch Upgrade

Some classic Studebaker owners choose to upgrade from the hydraulic switch to a more modern mechanical switch that mounts near the brake pedal. This conversion is more reliable, activates the lights instantly with pedal movement, and removes a potential hydraulic leak point. However, it is a custom job that requires fabricating a small bracket and rerouting wires. For most owners, a quality aftermarket hydraulic switch is the simplest and most direct repair.

Brake Light Switch Replacement Cost

The cost to replace the brake light switch on a 1959 Studebaker 4E12 is very reasonable, especially if you do the work yourself. The main cost is the part itself.

Part Type Estimated Cost
New Aftermarket (Standard Ignition) $15.52
New OEM (NOS) Not generally available
Used OEM $10 - $30 (Not Recommended)
Shop Labor $50 - $100

Frequently Asked Questions

Where is the brake light switch located?

The brake light switch on the 1959 Studebaker 4E12 is not inside the cab. It is a hydraulic pressure switch screwed directly into the brake master cylinder, which is located under the hood. It will have two wires connected to it.

Is it hard to replace the brake light switch myself?

No, this is an easy DIY job for most owners. The process involves disconnecting the wires, placing a rag to catch drips, and then quickly unscrewing the old switch and screwing in the new one to minimize brake fluid loss. However, it is highly recommended to bleed the brakes afterward to ensure no air has entered the system.

How do I test my current brake light switch?

First, confirm your brake light bulbs and the fuse are good. If they are, locate the switch on the master cylinder. Unplug the two wires and use a small jumper wire to connect the two terminals on the wiring harness together. If the brake lights turn on, the switch is bad. If they do not, the problem is elsewhere in the vehicle's wiring.

Are there any recalls for the 1959 Studebaker 4E12 brake light switch?

No. There are no recalls or Technical Service Bulletins (TSBs) from the National Highway Traffic Safety Administration (NHTSA) for this part on your vehicle. This is normal for a vehicle of this age.

Technical Specifications

OEM Part Numbers: 666858

Hydraulic Pressure Activated, 1/8-NPT Thread

Wrenchy
Article researched & written by
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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.

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