View Full Version : Low Oil pressure light installation

11-03-2007, 09:48 PM
Not being very good with all things electrical...I need some help!

I am adding a large idiot light to the bugeye for low oil pressure. I bought a gauge from Dennis Welch for my 1966 BJ8 and figured it would be better in th vintage racer. It came with a large light with 2 wires from it and a sending unit that has 2 blades on it.

Question is...what do I do? I am sure I need power and I have to ground something, but I don't know where to start!
Any ideas or someplace that has a diagram as to how this gets connected?

I do have the sending unit now on a tee with the oil pressure gauge.


11-03-2007, 09:58 PM
I can't seem to find the wiring diagram I know I have seen somewhere. I do recall how it's suppose to be hooked up though. One of the wires is positive, and the other goes from the light to one side of the sender. The other side of the sender should go to ground.

It is a pretty simple installation. I'll keep digging to see if I can find the diagram.

Hope this helps.

11-04-2007, 12:38 AM
You can snatch power from anywhere in the race car.

Personally...I like the buzzer (a loud one)

But I'm not very good at watching gauges in a racer.

11-04-2007, 03:25 AM
First, let's establish that your car has two posts on the battery.

In an orginal Bugeye, the positive (+) post of the battery would be grounded (big wire connected to the frame or body).
The other post would be negative (-) and insulated.

But many of these cars have been swithed to negative (-) ground (an easy job that makes things easier when fitting modern alternators and other devices).

So instead of saying positive (+) and negative, I will say "grounded" and "insulated". Then, all this will make sense no matter which way your car is set up.

Find any source of insulated power.
You can use a wire hooked directly to the insulated side of the battery if that is easiest.
This wire should have an in-line fuse in it (about 10 amp rating or less will do).
Hook this wire to either blade on the oil pressure sensor.
Connect a wire to the unused side of the pressure sensor and hook it to either wire that goes to the light.
The other wire on the light should go to a nearby metal ground (if you have metal dash, that should work).

Obviously, when the car is started, the light should go out.

The sensor is like an "on/off" switch.
When there is is no pressure, the sensor allows current to the light. Once the engine is started, the oil pressure moves a contact inside the senor to turn the power to the light "off".

11-04-2007, 04:50 AM
I agree except -shouldn't the insulated power source be taken from after the ignition switch otherwise the light will be on all the time except when engine is running?

11-04-2007, 07:27 AM
Yes. Correct.

I guess I'm thinking of this as a race car with a "Master Off" switch anyway. (which I always turn off right after engine shut down).
But come to think of it, since I suggested going to the battery, the light would still stay on. So forget that.

So, you could take insulated power from the "outgoing" side of the Master Kill switch.

Or, if you wish the light to go off with the ignition key (or switch) then use the ignition "on" terminal as the insulated power source. You can get this insulated power from the coil or the key switch. (mine comes from the coil)

11-04-2007, 08:20 AM
That sounds like I was figuring...it is now a Neg. ground car, and a race car with the master kill switch.

I'll give it a try later tonight...(After I watch the COLTS play in Indy!)

Thanks for the description, it makes sense and as I hope to race the car next year, I hope this light will keep from an accidential failure!!

11-04-2007, 08:24 AM
I would ask though..If I run from the coil for power, is the + side of the coil the side I want to get my power from?

11-04-2007, 09:11 AM
Yes, if you're negative ground.

11-05-2007, 06:07 PM
"""""""and a sending unit that has 2 blades on it. """"""

more than likely the two spade lugs are normally closed. With key on engine off the light will be on. With key on engine running the light will be off.

ground<----->0<------>|< ---->|<------- /. ---- B+
lite spade spade key/sw batt

You can test the sender with compressed air and a regulator and a VOM.

You want a sender that turns on at about 20-25 psi. You want a very bright 2" or so clearance light.

hope the wiring dia come out the way it shud........

11-05-2007, 08:04 PM
It works like a dream...I have a 30psi light, the car runs around 60psi on the gauge. The light is on lower than 30 psi and off above 30 psi.