1979-1983 GMC C3500 Turn Signal Switch Replacement Guide
Having trouble with your turn signals, brake lights, or hazard lights? Your turn signal switch is likely the culprit.
- A failing turn signal switch is a critical safety issue as it can disable your turn signals and brake lights.
- Replacement requires removing the steering wheel and using special tools like a lock plate compressor.
- Aftermarket brands like Standard Ignition are a reliable choice, but ensure you buy the correct part for a tilt or non-tilt column.
- This is a common failure point on Square Body GM trucks due to the age and plastic construction of the original switch.
Is Your Turn Signal Switch Failing?
The turn signal switch in these classic GMC trucks is made of plastic and contains small electrical contacts that wear out over time. After 40+ years, failure is common. Watch for these signs:
- Turn signals don't work or work intermittently: This is the most obvious sign. You might find they work on one side but not the other, or not at all.
- Signals don't cancel: The self-canceling mechanism can break, forcing you to manually turn the signal off after a turn.
- Brake lights don't work correctly: You might lose one or both brake lights. Often, the brake lights will work until you use a turn signal, which can cause one of the brake lights to go out. This is a major safety issue.
- Hazard lights are inoperative: If the 4-way flashers don't work when you press the button, the switch is a likely suspect.
- High beams won't activate: Since the high beam switch is integrated, a faulty turn signal switch can prevent you from switching between high and low beams.
Brake Light Connection
The brake light wiring runs through the turn signal switch. This allows the same bulb filament to be used for both braking and signaling. When you activate a turn signal, the switch disconnects the brake light signal on that side and flashes the turn signal instead. A fault in the switch can interrupt the brake light circuit even when the signals aren't in use.
Choosing the Right Aftermarket Switch
Original GM parts for this switch are no longer manufactured, so you will be choosing from aftermarket options. The good news is that the aftermarket offers quality parts that meet or exceed the original specifications.
Your main choices will be between brands like Standard Ignition and store or "Replacement" brands.
- Standard Ignition (Standard Motor Products): Often considered a higher-tier aftermarket brand, Standard is known for producing reliable parts that are trusted by professional technicians. They focus on quality control and use durable materials like copper alloy conductors to ensure good performance. While they might cost a few dollars more, they are a solid choice for durability.
- Replacement Brands: This category includes various house brands or value-focused manufacturers. For a straightforward part like this, these switches are often perfectly adequate and offer a good value. They are designed to be direct-fit replacements and will restore original function.
Pro Tip: Pay close attention to whether the switch is for a column with a tilt or non-tilt steering wheel. They are different parts. The 1979-1983 models should not require a wiring adapter harness like earlier trucks.
Replacement Cost
The cost to replace the turn signal switch is reasonable, especially if you do the work yourself. The main cost variable is shop labor if you choose to have a mechanic do it.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Part | $44.50 - $61.86 |
| Shop Labor | $150 - $250 |
| Total (Professional Install) | $195 - $312 |
Frequently Asked Questions
Is this a difficult part to replace myself?
It's a moderately difficult job that requires special tools. You must remove the steering wheel and use a steering wheel lock plate compressor to access the switch. The switch is held in by a few screws, but you also have to carefully feed the wiring harness down the steering column. It is very feasible for a DIY mechanic with the right tools.
What special tools are needed for the job?
You will need a steering wheel puller and a steering wheel lock plate compressor tool. These can often be rented from auto parts stores. You will also need basic hand tools like a socket set and screwdrivers.
Why did my brake lights stop working when the turn signal switch failed?
The power for the brake lights passes through the turn signal switch. This design allows the switch to interrupt the brake light on one side to flash the turn signal. When the internal contacts of the switch fail, it can break the connection to the brake lights permanently.
Do I need to worry about recalls for this part?
No. While you can always check for recalls on the NHTSA website, there are no active or historical recalls specifically for the turn signal switch on 1979-1983 GMC C3500 trucks. Failures are due to the age and material of the part, not a manufacturing defect.
Technical Specifications
Varies based on tilt or non-tilt steering column. The switch is a multi-function unit controlling turn signals, high/low beams, and 4-way hazard flashers. It includes a wiring harness with a specific plastic connector for the main vehicle harness.
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.