I have broken my '67 headlight switch again, and there are still no good alternatives for a long term repair - and fewer available switches on the market. There IS, however, a reproduction '69 headlight switch available, and I've been comparing the headlight vacuum diagrams from the sticky thread above ^^^^. Is there any reason I couldn't use the '69 two hose configuration over the '67 three hose configuration to make my headlights work? It's a very small change, and obviously I wouldn't need the thermal activation switch installed on the one vacuum line since I wouldn't need to open my grille covers in an overheating situation. It seems like the '69 just uses one less hose from the controller under the hood and doesn't route a full time vacuum to the switch. Everything else seems technically the same... Am I missing anything? Maybe the black and blue hoses need to be swapped around at the remote valve assembly?

1967


1969

 

The above diagram is not 69. That is 1968 W34 only. 68 and 69 both use 3 port vacuum switches on the headlight switch. The W34 actually used a 3 port switch as well, but the number 1 port was blocked off (if you look close at the image above, you can see port 1 left empty). My car had a 1" hose with a screw in the open end on the switch under the dash when I restored it. The control valve under the hood is specific to 68 W34. Regular 68 and 69 control valves need a vacuum signal from the headlight switch to open or close the doors. The 68 W34 gets a vacuum signal to close the headlight doors. Once vacuum is removed, the valve has a spring that defults to the open position. This is how the radiator thermal switch works. It blocks the vacuum source coming from the headlight switch and vents the hose going to the control valve to atmospheric pressure. With no vacuum signal coming from the headlight switch, the control valve defults to the open position and the headlight doors open. Now, everything written above is way more info than you need for your question. I suspect the only difference you will find if you get a 69 switch is in the operation of the parking lights. Until 1967, GM had the parking lights and tail lights come on when pulling the headlight switch out to the first position. When pullling to the second position, the tail lights stayed on, the parking lights turned off, and the headlights turned on. Starting in 68 the parking lights stayed on with the headlights.

 

Fabulous description of the ways these systems work. Thank you! And I appreciate the added info on the parking lights as well. I keep digging further and further into various other possibilities. I've been trying to find a 3-way ball valve or some other vacuum switch where I could just bypass the headlight switch completely with the vacuum. In my digging today I found a switch listed as for the GTO with hidden headlamps, and listing 8 pin connections, unlike the other 7 pin connection switches I've seen. The only difference visually with this switch was the direction of the vacuum connections (out instead of up). I ordered one just to see if there's a chance...of course it's backordered for 4 weeks. I'm trying to get this car roadworthy, and these little hiccups are killing me. Thanks again!


EDIT - follow up to this post - the headlight switch for the GTO with hidden headlamps works as an excellent replacement. The only differences are the size of the vacuum ports - you may have to splice or really stretch your hoses - and the positioning of the vacuum ports, which are 90 degrees off of the Olds, requiring some tight bends. Also the GTO switch will open your headlights in the parking light position, which is actually better for changing bulbs and cleaning.

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