Car is a 72 sb. Just replaced vacuum hoses, filter, check valve, and headlight switch. Everything worked fine when I tested it with the dash apart. Put the dash back together, started the car, then the headlights popped up with the switch in the off position and the override pushed in. Also, the wiper door comes up now when I shut the engine off, and goes back down when the engine is running. I can hear hissing at the check valve after shutting down the engine. Could this indicate a bad check valve? Any suggestions would be appreciated.

Thanks,
Heath

 

Hi Heath,
The headlight and wiper system can be quite a puzzle, and VERY frustrating.
The system is designed with 2 parts:
The "control" side which is made up of the switches, relays, solenoids and the SMALL hoses.
The "servo" side which is made up of the actuators and the LARGE hoses.
The system is biased so that with the same amount of vacuum the control side (small hoses) receives it's full vacuum before the servo side (large hoses) does because of the hose side.
The system is also designed so that upon start-up of car the relays are signaled to stay where they are set so the doors are signaled to stay closed. The same thing is true upon shut down.
Your car has what is known as winking headlights and dancing wiper door. Uncontrolled movement.
Look for a problem on the "control" side of the system.
Start by checking the function of the gray metal one-way valve and the white plastic filter on the vacuum line coming off the manifold.
Then check the connections at the wiper switch, the over-rides, the tach servo, the wiper safety solenoid, and the relays.
If the connections are all as they should be you'll need to check the function of each part. Do you have a trouble shooting guide that tells how to check the function of each part?
Sometimes it's just one thing that causes the system to act up, but often it's several things.
Good Luck!
Regards,
Alan