Idiot (light) Question

Need some help to finish my wiring on the Roadster. I have everything done as far as the wiring goes but early on I decided to put a red idiot light in so I would be able to see at a glance if the ignition switch was on. I can't figure how to hook it up, I know it is hooked in series to a hot wire but from where? I've tried a couple of combinations but nothing I've done will turn the lite on with the ign. on and turn it off after it's started. I already have the lite installed in the dash or I would just forget about it. If anyone can answer this for me I thank you in advance.

 

Most sending units act as a ground for your light. IGN term on the ign switch should work for the power supply.

 

Easiest way would be to get an oil light pressure switch, it has only one terminal. Connect one side of the light to the Ignition circuit. Connect the other side of the light to the pressure switch terminal.

These pressure switches are normally closed, so it will provide ground to the light when the engine is not running. When the engine starts and it gets oil pressure, the pressure switch turns off, so the light will turn off. When you turn off the key, the light won't get power so it will go off.

 

Hook it up kinda the same way an alternator light is, a single 194 bulb, one side comes from the ignition switch, the other to an oil pressure switch for early 80s gm car. I "think" that it will turn off while running, I'd have to check for the right part number that grounds w/o pressure.

Damn, you beat me.

 

I'd use one for a 60s-70s car...they went to two prong switches in the early 80s to run the electric choke.

 

Thanks, I knew there had to be an easy answer, I think I have a oil sending unit in my box of electrical stuff.

Oldschool66

 

If you want the light ON only when the key is ON and the engine is NOT running, wire it like an alternator idiot light.... the bulb goes between the key RUN (or ON) terminal and the alternator field connection.

 

That might work too....I have two idiot lights in my 55, one for the alternator, one for the oil pressure, they have the added bonus of telling me when I lose oil pressure or throw a belt. I can usually tell when the engine quits running because the car gets real quiet.

 

That sounds like a winner to me. You can never have to many ways to let you know when things are headed south, Thanks 440


Oldschool66

 

what switch will ground without pressure as mentioned by 53Sled?

 

I like That Guys answer will let you know when you're charging.