Assist light under the hood. How does it work?

[croderique]

On my 1964 Chrysler 300, under the hood is an assist light. You pull it up and out and unwind the cord. All of a sudden it came on and stays on. What is the trick to turn it off? There is some kind of switch above it but it is not connected to the light that I can tell.
In the pic I have disconnected the battery so it won't run down.
Thanks
Chuck

 

[CBODY67]

Absent a formal on-off switch, the internal switch is a mercury switch. With the light in a more vertical orientation, the switch is closed and the light is on. When the light is in a more horizontal orientation, the switch opens and the light turns off. This type of underhood light was a big deal in the 1960s and GM used it into the later 1970s.

Trace the single wire going to the light back and you should find a plug-in connector somewhere, as it was usually an accessory item back then, added at the dealership or otherwise. Then you can unplug the wire there rather than unhooking the battery. The light should be grounded to the body to work, too.

If the light can be unhooked from its retainer, and then you pull a wiring cord so you can move the light around, the mercury switch should be attached to the hood structure somewhere. So the light would be on with the hood up.

Enjoy!
CBODY67

 

[fullsized]

That looks like the same one as on my 60 Pontiac. Is that a push button at the top? Pull the light up vertical and it will slide out. rotate it around ti see if it goes out at all. While many are mercury switches many were also a small steel ball that would roll around and connect to a mechanical point inside and close the switch. The wire that is wound around the base is long! Can walk it back to the rear tire for night time use...