1951-1959 GMC 150 Brake Light Switch Replacement and Diagnosis
Get your classic GMC's brake lights working reliably with the right information on choosing and installing a new switch.
- The most common symptoms of failure are brake lights that don't work at all or stay on constantly.
- The switch is typically located under the cab floor, activated by the brake pedal arm.
- Replacement is simple and a good DIY task for owners with basic tools.
- High-quality aftermarket parts from brands like Standard Ignition are the standard and most practical repair solution.
Symptoms of a Failing Brake Light Switch
On a classic truck like the GMC 150, the signs of a bad brake light switch are straightforward. Because the truck has a simple electrical system, you won't see modern issues like ABS lights or problems with cruise control. Look for these two primary symptoms:
- Brake Lights Do Not Turn On: This is the most common and dangerous symptom. If the switch fails in the 'open' position, the circuit never closes, and your brake lights will not illuminate when you press the pedal.
- Brake Lights Stay On: If the switch fails in the 'closed' position, it will send continuous power to the brake lights. This will drain your battery and confuse drivers behind you.
Safety First
Driving without functional brake lights is extremely dangerous and illegal. If you suspect your brake light switch has failed, you should not drive the vehicle until it is repaired.
Choosing the Right Aftermarket Switch
For a vehicle from the 1950s, finding new original equipment (OEM) parts from GM is not possible. The market consists of New Old Stock (NOS) parts, which are rare and expensive, and new aftermarket parts.
- OEM Quality vs. Aftermarket: For a simple part like a brake light switch, a quality aftermarket brand provides a reliable and affordable solution. Brands like Standard Ignition are long-established manufacturers that produce direct-fit replacement parts meeting or exceeding original specifications.
- Brand Focus - Standard Ignition: Standard Ignition is a well-regarded brand in the aftermarket industry, known for its quality control and testing processes. For the 1951-1959 GMC 150, their switches are designed to be a direct replacement, ensuring an easier installation.
Check Fitment on Reproduction Parts
When working on classic vehicles, even quality reproduction parts can sometimes have minor differences from the original. Some owners of similar vintage trucks have noted that the activation point on a new switch can differ slightly. Be prepared to make small adjustments to the switch's position or the pedal stop to ensure it activates correctly when the pedal is pressed and deactivates when released.
Estimated Replacement Costs
Replacing the brake light switch is an inexpensive repair, especially if you do it yourself.
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket (e.g., Standard Ignition) | $25 - $41 |
| Shop Labor | $60 - $120 |
| Total Estimated Cost | $85 - $161 |
Cost estimates are for reference only and may vary based on location and supplier.
Frequently Asked Questions (FAQ)
Where is the brake light switch located on a 1951-1959 GMC 150?
On many trucks from this era, including the 1955-1959 models, the brake light switch is a mechanical switch located under the floor of the cab, near the brake pedal arm. You will need to look underneath the truck to access it, as opposed to under the dashboard like in many later vehicles.
Can I replace the brake light switch myself?
Yes, this is a very DIY-friendly job. It typically requires only basic hand tools to unbolt the old switch, disconnect the two wires, and install the new one. The difficulty is low, and it can usually be done in under an hour.
Are there any recalls for the brake light switch on this truck?
No. There are no recalls or Technical Service Bulletins (TSBs) on record with the NHTSA for the 1951-1959 GMC 150. Public recall databases generally do not cover vehicles from this time period.
What is the difference between the two available Standard Ignition switches?
The two available products likely correspond to different designs used across the 1951-1959 year range. There may have been a design change, particularly around 1954-1955 when the truck body style was updated. Always verify the part number and appearance of your original switch before ordering to ensure you get the correct replacement.
Technical Specifications
Mechanical, 2-terminal switch activated by brake pedal movement.
We Have This Part in Stock
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.