Replacing the Brake Light Switch on Your 1951-1954 GMC 150-22 Truck
Keep your classic truck safe and on the road by understanding this simple but critical part.
- A faulty brake light switch is a critical safety issue that must be fixed immediately.
- Symptoms are simple: lights don't work, stay on, or are intermittent; there are no computer codes on this truck.
- Replacement is an easy and inexpensive DIY job, with the main difficulty being physical access under the dash.
- A new aftermarket switch from a reputable brand like Standard Ignition is the best and most reliable choice.
Is Your Brake Light Switch Failing?
On a classic truck like the GMC 150-22, the brake light switch is a simple part, and its failure symptoms are usually obvious. Because this component is directly tied to safety, you should address any issues immediately. Look for these common signs of a bad switch:
- Brake Lights Don't Work at All: The most common and dangerous symptom. The switch has failed internally and no longer completes the electrical circuit when you press the brake pedal.
- Brake Lights Stay On: The switch can fail in the 'on' position, causing the brake lights to remain lit even when your foot is off the pedal. This can drain your battery and confuse drivers behind you.
- Intermittent Brake Lights: The lights might flicker or only work some of the time. This indicates the switch is worn out and complete failure is imminent.
Critical Safety Warning
Driving without functional brake lights is illegal and extremely dangerous. It dramatically increases the risk of a rear-end collision. If you suspect your brake light switch has failed, do not drive the vehicle until it is repaired.
Choosing the Right Aftermarket Switch
For a vehicle from the early 1950s, finding "new old stock" (NOS) or original equipment (OEM) parts is extremely difficult and often unnecessary for a simple switch. The market primarily consists of aftermarket reproductions.
- New Aftermarket (Recommended): Brands like Standard Ignition (Standard Motor Products) are a reliable choice for these trucks. They produce quality parts that meet or exceed the original specifications. Given the low cost of the part, a new, quality aftermarket switch is the best and safest option.
- New Old Stock (NOS): While providing original quality, NOS parts are rare, can be very expensive, and may have degraded from decades of storage. They are not necessary for a simple component like this.
- Used OEM: A used switch is not recommended. It's a low-cost part, and you have no way of knowing the condition or remaining life of a used electrical component.
Typical Costs
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket | $15 - $30 |
| New OEM (NOS) | $50 - $100+ (if found) |
| Used OEM | $5 - $15 (Not Recommended) |
| Shop Labor | $50 - $100 |
Installation Pro-Tip
Replacing the switch is mechanically simple, but its location under the dash can be awkward to reach. You'll likely be on your back in an uncomfortable position. Using a cushion and having good lighting will make the job much easier.
Frequently Asked Questions (FAQ)
Where is the brake light switch located on my GMC 150-22?
The brake light switch is typically mounted on a bracket under the dashboard, near the top of the brake pedal arm, or on the firewall where the pedal assembly is located. Its plunger makes contact with the pedal arm.
Is replacing the brake light switch a DIY job?
Yes, this is a great DIY job for a home mechanic. It requires only basic hand tools and can usually be done in less than an hour. The main challenge is the awkward access under the dashboard.
Are there any recalls for the brake light switch on this truck?
No. Searches of the NHTSA database show no open or past recalls specifically for the brake light switch on the 1951-1954 GMC 150-22. Recalls found for GM brake switches are for much newer vehicles.
Will a bad brake light switch show a check engine light or error code?
No. Vehicles from this era do not have On-Board Diagnostics (OBD) or check engine lights. Diagnosis is based purely on the operational symptoms of the brake lights themselves.
Technical Specifications
OEM Part Numbers: 1997901 1997912 1997915 1997922 19106739
The primary aftermarket part number is Standard Ignition SLS-40. It is a 2-terminal, mechanical, push-style switch that mounts with a bracket.
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.