a part i don't know what it is

silly question. there is a small vacuum /electric switch on the left fender apron right by washer reservoir.It has 1 vacuum line and 2 wires, one with a resistor. If i disconnect vacuum line left fender turn indicator lights up. Anyone tell me what it is actually for? 76 Cordoba 400. was one on my former 77 Cordoba also. thanks for any reply, Jack

It is an acceleration warning light in the left fender-mounted turn signal indicator. If the accelerator was tramped too vigorously, the manifold vacuum activated the “Fuel Pacer” an intake manifold-pressure sensor hooked to a warning light that glowed during heavy-footed moments.
It was an option started in 1975 to help with fuel economy.
The blinker lights up when you pull the vac line because it thinks the gas pedal is on the floor and the engine Vac as low.

I googled it for you.Here is a little bit more info for you :) with pic's.

http://www.nybclub.org/m-r/engine/FuelPacer/index.htm

Thanks for the info. I figured it would be something to that effect. just is annoying when you drive in the mountains all the time with a low vacuum worn out engine. Soon will rebuild engine and re connect it then.