1978-1986 Chevrolet Impala Headlight Dimmer Switch: Replacement and Guide
If your Impala's high beams are acting up, the dimmer switch on the steering column is a likely suspect.
- The dimmer switch for the 1978-86 Impala is on the steering column, not the floor, and is activated by the turn signal lever.
- Common symptoms include headlights stuck on one beam, flickering, or not working at all.
- Replacement is a DIY-friendly job that takes about an hour with basic tools.
- Both ACDelco (OE) and Standard Ignition (Aftermarket) are high-quality, reliable brand choices for this part.
Symptoms of a Failing Headlight Dimmer Switch
When the dimmer switch starts to fail, it can cause several noticeable and potentially dangerous lighting problems. Because it's a mechanical switch with electrical contacts, it can wear out over time. Here are the most common signs that your Impala's dimmer switch needs replacement:
- Headlights Stuck on One Beam: The most common symptom is being unable to switch between high and low beams. You might be stuck with only low beams, or worse, stuck with high beams that can blind other drivers.
- Flickering Headlights: An internal short or worn contacts in the switch can cause the headlights to flicker or cut out entirely, especially when you hit a bump.
- High Beams Don't Stay On: You might pull the lever and the high beams come on, but they turn off as soon as you let go. The switch is failing to lock in the high beam position.
- No Headlights at All: In cases of complete failure, the switch can break the connection entirely, leaving you with no headlights. However, if only one headlight is out, the problem is more likely a bulb or wiring to that specific light.
Choosing the Right Aftermarket Dimmer Switch
For a classic vehicle like the 1978-1986 Impala, finding "new old stock" (NOS) OEM parts is difficult and expensive. Aftermarket parts are the most practical solution. The two main brands available, ACDelco and Standard Ignition, are both excellent choices.
| Brand | Quality & Reputation | Best For |
|---|---|---|
| ACDelco | ACDelco is General Motors' own parts brand, making it the original equipment (OE) manufacturer for your Impala. Choosing ACDelco is the closest you can get to putting a factory part back in your car. They are known for perfect fitment and adhering to GM's original specifications. | The owner who prioritizes originality and wants the exact part the car was built with. |
| Standard Ignition (SMP) | Standard Motor Products is a top-tier aftermarket manufacturer with a long history of producing high-quality electronic parts that meet or exceed OE standards. They are a trusted brand used by many professional technicians. For a simple part like this switch, their quality is considered just as reliable as OE. | The owner looking for a high-quality, reliable part that may offer a better price point than the OE-branded equivalent. |
Pro Tip: For this specific part, you can't go wrong with either brand. Both are known for reliability. The best choice often comes down to price and immediate availability.
Typical Replacement Costs
The cost to replace the headlight dimmer switch is reasonable. The part itself is affordable, and if you hire a mechanic, the labor is typically not extensive.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Part (ACDelco, Standard) | $54.87 - $84.63 |
| Shop Labor | $100 - $180 |
| Estimated Total | $155 - $265 |
Note: Labor costs can vary significantly based on your location and the specific auto shop's hourly rates.
Frequently Asked Questions (FAQ)
Can I replace the headlight dimmer switch myself?
Yes, this is a very manageable DIY project for someone with basic tools. The process involves removing the lower dash panel to get access to the steering column. You will likely need to unbolt the steering column to let it drop slightly for better access to the switch, which is held on by two small screws. The main challenge is working in a tight space. The job typically takes about an hour.
Where is the headlight dimmer switch located?
It is located on the upper part of the steering column, under the dashboard. It is not on the floor or part of the turn signal lever itself. You must remove the lower dash trim panel to see and access it.
Do I need any special tools?
No special tools are required. A basic socket set (you may need both metric and standard sizes for 80s GM vehicles), screwdrivers, and possibly a small pry tool for trim will be sufficient. A flashlight or headlamp is also very helpful for seeing under the dash.
My high beams don't work, but there's no 'click' when I pull the lever. Is it the switch?
Most likely, yes. The audible 'click' comes from the switch itself. If you don't hear that click, it means the switch is either broken internally or has slid out of adjustment. Before replacing it, you can try loosening the two mounting screws and sliding the switch slightly to see if the actuating rod can make proper contact. If that doesn't work, a replacement is needed.
Could my problem just be a fuse?
It's possible, but less likely to cause the specific symptoms of a bad dimmer switch. A blown fuse would typically cause both high and low beams to stop working at once, not get stuck on one setting or flicker. It's always a good idea to check fuses first as it's a quick and easy step, but the symptoms described above point strongly to the switch itself.
Technical Specifications
OEM Part Numbers: D817
Steering column mounted switch activated by a pushrod from the turn signal lever.
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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.