* Vacuum System Issues: The 1971 Corvette used a vacuum system to operate the headlights. Problems within this system are the most common cause. This could include:
* Leaks in the vacuum lines: Cracks, holes, or loose connections in the vacuum hoses can prevent sufficient vacuum from reaching the actuators.
* Faulty vacuum pump: The pump might be failing to generate enough vacuum.
* Vacuum reservoir issues: The reservoir (if equipped) might be leaking or not holding a sufficient vacuum.
* Vacuum actuator problems: The actuators themselves (the units that actually move the headlights) could be worn, seized, or leaking.
* Electrical Issues (less common for the up/down function): While the primary system is vacuum-based, there might be a secondary electrical component involved in the headlight operation (such as a switch or relay). A problem here could cause malfunction.
* Manual Override: While unlikely to cause the headlights to *go down* spontaneously, it's worth remembering that there's typically a manual override system. It's possible someone accidentally engaged it.
Troubleshooting:
To diagnose the problem, you'll need to systematically check the vacuum system. Start by:
1. Inspecting the vacuum lines: Look for cracks, holes, or loose connections. Replace any damaged lines.
2. Checking the vacuum pump: Listen for the pump operating when the headlights are switched on. A weak or non-functional pump needs replacing.
3. Testing the vacuum reservoir (if present): See if it holds a vacuum.
4. Examining the vacuum actuators: Check for any signs of damage, binding, or leaks. You may need to lubricate them (with the appropriate lubricant, not WD-40).
If the vacuum system checks out, then you might need to investigate the electrical components. This could require more advanced diagnostic skills or a qualified mechanic.
