Remove and replace the headlight switch on a 1966 Chevrolet Corvette, including disconnecting the battery, accessing the switch from under the dashboard, and testing operation.

Warnings

Tools required

Parts

• Headlight switch × 1 — Use OEM specification
• Headlight switch connector (if damaged) × 1 — Use OEM specification

Preparation

1. Park the vehicle on a level surface and engage the parking brake
2. Disconnect the negative battery cable and secure it away from the battery terminal
3. Allow adequate time for any residual electrical charge to dissipate (approximately 5 minutes)
4. Position a drop cloth or mat on the driver's side floor to protect interior and provide cushioning
5. Gather all tools and have the replacement headlight switch ready for installation

Procedure

1. 1

   Access the headlight switch from under the dashboard
   Position yourself on the driver's side floor with your back on the mat, looking up at the underside of the dashboard. Locate the headlight switch mounted in the dash panel to the left of the steering column. Use the flashlight to illuminate the area and identify the switch body, which is cylindrical and approximately 2 inches in diameter, mounted from behind the dash panel.
2. 2

   Identify and note the electrical connector orientation
   Before disconnecting anything, examine the multi-pin electrical connector attached to the rear of the headlight switch. Note the orientation and position of the connector, as it can only be installed one way but identifying the correct alignment now will ease reassembly. The connector has a locking tab that must be depressed to remove it.
3. 3

   Disconnect the electrical connector
   Using your fingers or needle-nose pliers if needed, depress the locking tab on the electrical connector while gently pulling it straight back away from the switch. The connector should release with moderate force. If it resists, do not force it; verify the locking tab is fully depressed and wiggle the connector gently while pulling. Set the connector aside where it will not contact any metal surfaces.
4. 4

   Locate the switch shaft release button
   With the connector removed, you can now see the rear of the switch body more clearly. On the switch housing, locate the small spring-loaded shaft-release button. This button releases the switch shaft (the knob shaft that protrudes through the dashboard face). On the GM-style switch it is a small round plunger located on the top or upper portion of the switch body.
5. 5

   Depress the release button and remove the switch knob shaft
   From inside the passenger compartment, gently pull the headlight switch knob outward approximately 1 inch as if turning on the headlights. While holding the knob in this position, use a flathead screwdriver or your finger to depress the release button on the switch body from underneath the dash. While holding the release button depressed, continue pulling the knob and shaft assembly straight out through the front of the dashboard. The entire shaft and knob will come free as one unit. Set it aside in a safe location.
6. 6

   Remove the switch bezel nut
   From the front of the dashboard, you will now see a threaded bezel nut (ferrule) surrounding the hole where the switch shaft was. This nut secures the switch body to the dashboard. Using a proper switch-nut spanner wrench (or a flat-blade tool engaging the notches), unscrew this bezel nut by turning it counterclockwise; avoid pliers that can scratch the chrome bezel. The nut may be tight from years of installation, so apply steady pressure. Once loose, remove the nut completely and set it aside.
7. 7

   Remove the headlight switch from the dashboard
   Return to your position under the dashboard. With the bezel nut removed and the electrical connector disconnected, the switch body is now free. Grasp the switch body from behind and pull it straight back through the dashboard opening toward the interior of the vehicle. The switch should slide out easily. Remove the switch completely and inspect the mounting hole for any debris or corrosion.
8. 8

   Prepare the new headlight switch
   Remove the new headlight switch from its packaging. Verify that the switch body matches the old switch in terms of size, connector type, and shaft configuration. If the shaft and knob are separate from the new switch, do not install them yet. Clean the mounting hole in the dashboard with a wire brush or cloth if any corrosion or debris is present.
9. 9

   Install the new switch body into the dashboard
   From underneath the dashboard, insert the new switch body up through the mounting hole from behind, positioning it so the shaft opening faces forward and the electrical connector port faces toward the interior where you can access it. Push the switch forward until it is fully seated against the back of the dashboard panel and the threaded collar protrudes through the front.
10. 10

    Secure the switch with the bezel nut
    From the front of the dashboard, thread the bezel nut onto the switch collar by turning it clockwise. Tighten the nut finger-tight, ensuring the switch body is properly aligned and not rotated. The switch should sit flush and secure. Do not overtighten, as this can crack the dashboard or damage the switch housing.
11. 11

    Install the switch shaft and knob assembly
    Take the switch shaft and knob assembly (either the original if reusing, or the new one if included with the replacement switch). From the front of the dashboard, align the shaft with the switch body opening and insert it straight into the switch. Push the shaft in until you hear or feel a positive click, indicating the shaft has locked into place within the switch mechanism. Gently tug on the knob to verify it is secured and will not pull free.
12. 12

    Reconnect the electrical connector
    From underneath the dashboard, take the electrical connector and align it with the connector port on the rear of the switch, matching the orientation you noted during disassembly. Push the connector straight onto the switch until the locking tab clicks into place. Gently tug on the connector to verify it is fully seated and locked.
13. 13

    Reconnect the battery and test switch operation
    Reconnect the negative battery cable to the battery terminal and tighten securely. Turn the ignition key to the "On" position (engine does not need to start). Pull the headlight switch knob out to the first detent to verify the parking/marker lights, then to the second (fully out) detent to verify the headlights turn on. Verify the hidden headlight doors rotate up and the lamps illuminate, then test both low and high beam operation using the floor-mounted dimmer switch. Rotate the switch knob clockwise to verify the instrument panel rheostat dims and brightens the dash lights smoothly through its full range of travel. Push the knob all the way in to verify the headlights turn off.

Reassembly

1. Verify all electrical connections are secure and the switch operates smoothly through all positions
2. Ensure the bezel nut is snug but not overtightened to prevent dashboard damage
3. Test the parking light function if the switch includes this feature by pulling the knob to the intermediate detent position

Verification

• With the ignition on, pull the headlight switch to verify headlights illuminate in both low and high beam positions
• Rotate the switch knob to confirm the instrument panel lighting dims and brightens smoothly without flickering or dead spots
• Push and pull the switch knob several times to ensure it moves freely and locks positively in each detent position
• Verify no warning lights remain illuminated on the instrument cluster that would indicate an electrical fault
• Check that the switch knob does not feel loose or rattle in the dashboard opening

More procedures for this vehicle