Your 1968-1974 GMC K35/K3500 Pickup Headlight Switch Replacement Guide
Don't get left in the dark—learn the signs of a failing headlight switch and how to replace it.
- Symptoms of a bad switch include flickering lights, total light failure, or non-working dash lights.
- This is a simple DIY repair that most owners can complete in under an hour with basic tools.
- Before replacing the switch, always check for bad grounds and test the floor-mounted dimmer switch, as these can cause similar issues.
- Aftermarket brands like Standard Ignition offer reliable, high-quality replacements for this common GM part.
Is Your Headlight Switch Failing? Common Symptoms
On a classic truck like the K35/K3500, the headlight switch is a mechanical part that sees a lot of use. After decades of service, it's common for the internal contacts to wear out, corrode, or overheat. Recognizing the signs of failure can save you from a dangerous situation where your lights go out unexpectedly.
- Flickering or Intermittent Headlights: Lights that cut in and out while driving are a classic sign of a worn switch.
- Headlights Won't Turn On: You pull the knob and nothing happens, even though your parking lights may still work. This can indicate a complete failure inside the switch.
- Dash Lights Don't Work or Dim: If you can no longer adjust the brightness of your instrument panel by twisting the knob, the switch's internal rheostat has likely failed.
- Burning Smell or Hot Switch: A faint smell of burning plastic or a switch that is hot to the touch indicates overheating, which is a serious fire risk and requires immediate attention.
Pro Tip: Check Other Components First
Before you replace the headlight switch, check for simpler issues. Bad grounds are a very common problem on these older trucks and can cause similar lighting problems. Also, check the floor-mounted high-beam dimmer switch, as they are known to fail and can prevent headlights from working correctly.
Choosing the Right Aftermarket Headlight Switch
For a vehicle of this age, new Original Equipment (OEM) parts are generally not available from dealers. The aftermarket offers excellent, readily available solutions that meet or exceed original specifications.
The headlight switch for the 1968-1974 GMC K35/K3500 is a common part shared across many GM cars and trucks of the era, making it easy to find. Your choice will typically be between two tiers of aftermarket brands:
- Standard Ignition (SMP): A well-known and respected brand in the aftermarket industry. Standard Motor Products parts are known for their quality, durability, and adherence to OEM specifications. Choosing this brand is a solid investment for reliability and peace of mind.
- Replacement Brand: These are value-oriented parts that offer a direct-fit replacement at a lower cost. For a truck that is used less frequently or if budget is the primary concern, a "Replacement" branded switch is a functional and economical choice.
Headlight Switch Replacement Cost
Replacing the headlight switch is an affordable repair, especially if you do it yourself. The part itself is inexpensive, and the labor is straightforward.
| Part Type | Estimated Price Range |
|---|---|
| New Aftermarket (Replacement, Standard Ignition) | $27.74 - $58.42 |
| Shop Labor for Installation | $75 - $150 |
| New OEM (NOS) | Not Generally Available |
| Used OEM (Junkyard) | $10 - $25 (Not Recommended) |
Prices are estimates and can vary based on supplier and location. Used parts are not recommended due to their unknown condition and age.
Frequently Asked Questions (FAQ)
Is it hard to replace the headlight switch myself?
No, this is a very DIY-friendly job with a difficulty of 1 out of 5. The process involves disconnecting the battery, reaching under the dash to press a release button on the switch body, which allows the knob and shaft to pull out. Then you unscrew a retaining nut from the front of the dash, unplug the old switch, and reverse the process. The only challenge can be reaching the switch if your truck has a lot of under-dash options like A/C ducting.
Are there any recalls for the headlight switch on my truck?
No. Searches of the National Highway Traffic Safety Administration (NHTSA) database show no recalls or technical service bulletins (TSBs) specifically for the headlight switch on the 1968-1974 GMC K35/K3500 Pickup. Any failures are due to the age and normal wear of the original component.
Do I need a special tool to remove the headlight switch?
Usually, no special tools are required. You will need basic hand tools like a screwdriver. The retaining nut on the dash has two small slots; while a special tool exists, it can typically be loosened and tightened carefully with needle-nose pliers or a flat-head screwdriver.
My headlights work, but my dash lights don't. Is it the switch?
Most likely, yes. The ability to dim the dash lights is controlled by a rheostat built into the headlight switch. When this part of the switch fails, it's common to lose dash lighting while the headlights continue to function normally. Twisting the knob should adjust brightness; if it doesn't, the switch needs replacement.
Technical Specifications
OEM Part Numbers: 1995122 1995123 1995142 1995147 1995149 1995150 1995151 1995163 1995164 1995165 1995173
Dash-mounted pull/twist knob switch. Typically features an 8-pin rectangular connector. Controls headlights, parking lights, instrument panel dimming, and dome light.
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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.