1975-1978 GMC P15 Brake Light Switch Location, Symptoms, and Replacement
If your brake lights are stuck on or won't light up at all, the problem is likely this small, easy-to-replace switch.
- A faulty brake light switch will either cause your brake lights to fail completely or stay on constantly.
- This is a very simple and inexpensive DIY repair that can be completed with basic tools in under 30 minutes.
- Verify if your P15 has cruise control before ordering, as it may require a different switch.
- Standard Ignition is a reputable aftermarket brand for this part; OEM parts are no longer available.
Is Your Brake Light Switch Failing?
On a workhorse vehicle like the GMC P15, mechanical parts like switches wear out over time. The brake light switch is used every time you drive. After decades of use, the internal contacts can fail, or the plastic body can become brittle and break. The symptoms are usually straightforward and signal an immediate need for replacement.
Key Failure Symptoms
- Brake Lights Don't Work: The most serious symptom is when your brake lights do not turn on at all when you press the pedal. This is a major safety hazard.
- Brake Lights Stay On: The switch can also fail in the 'on' position, causing the brake lights to stay lit even when your foot is off the pedal. This can drain your battery and confuse drivers behind you.
- Cruise Control Won't Disengage: If your P15 has cruise control, a faulty switch may prevent it from turning off when you press the brake pedal.
Choosing the Right Aftermarket Switch
Original OEM brake light switches for this vehicle are no longer manufactured. Aftermarket parts are your only option, but quality can vary. For a simple but crucial safety part, it's best to understand the difference between brands.
| Brand Tier | Our Available Brands | Quality & Notes |
|---|---|---|
| Standard Replacement | Standard Ignition (SMP) | Standard Ignition is a well-known and trusted aftermarket brand that has been around for decades. Their electrical components are generally considered to be reliable, direct-fit replacements that meet or exceed original specifications. For a critical safety part, this is a dependable choice. |
| Economy | Skyward | Economy brands offer a low-cost alternative. While functional, they may not have the same long-term durability or precise fit as higher-tier brands. For a part that is easy to access and inexpensive, this can be a viable budget option, but check the warranty period. |
Common Ordering Mistake
The brake light switch for the 1975-1978 GMC P15 can be different depending on whether your vehicle has cruise control. Be sure to verify this feature on your truck before ordering to ensure you get the correct part.
How Much Does a New Brake Light Switch Cost?
Replacing the brake light switch is one of the most affordable repairs you can perform on your P15. The part itself is inexpensive, and if you have it done at a shop, labor costs should be minimal.
| Part or Service | Estimated Cost |
|---|---|
| New Aftermarket Part | $5.40 - $29.97 |
| Shop Labor | $50 - $100 |
Frequently Asked Questions (FAQ)
Can I replace the brake light switch myself?
Yes, this is a very easy job for a DIY mechanic. It typically requires no special tools and can be done in under 30 minutes. The switch is located under the dash by the top of the brake pedal arm and is usually held in place by a simple clip.
Where is the brake light switch located on my GMC P15?
Look under the driver's side dashboard, directly above the brake pedal. You will see the switch mounted on the pedal support bracket, with a wiring harness connected to it.
Are there any recalls for the 1975-1978 GMC P15 brake light switch?
No. A search of the National Highway Traffic Safety Administration (NHTSA) database shows no safety recalls for the brake light switch on this vehicle.
Could a blown fuse cause the same problem?
Yes, before replacing the switch, it's always a good idea to check the fuse for the brake lights (often labeled 'Stop Lamp' or similar in the fuse panel). A blown fuse can also cause the brake lights to fail.
Technical Specifications
Located on brake pedal support. Mechanical plunger type switch. May vary for models with or without cruise control.
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.