Headlight power wires ground continuity

[Fairlane514]

29 Tudor with early headlight like the 28.

I did a continuity test from ground to each wire in side the socket of the headlights. Both green and red show continuity to ground.

My issue is my safety fuse (30 amp) blows when I turn on the high beams.

I just go this car and some wiring was generic so I replaced it with correct harnesses. I did not replace the light harness, it was correct and looked in decent shape.

Headlight bulbs were burned out, so I got new correct ones (32-50). Low beams are fine, horn is fine, tail light etc....only when I turn to high beam, then the fuse blows. Obviously something is shorting. Visual shows no breaks.

So just curious if I should have continuity to ground from the socket wires.

[Kurt in NJ]

without the bulb no, with good bulb yes

[Fairlane514]

Ok, thanks

Bulbs are out, battery disconnected

Im going to check continuity from the switch "plate" where the wires terminate and see what I have to the socket with bulbs out.

[Bill G]

In a stock headlight system, there is the socket that the bulb twists into and the socket at the base of the headlight bucket. Both of these sockets have small spring-loaded pads that come into contact with the bulb in the case of the light socket, or the end of the harness in the case of the socket at the base of the buckets. The springs on the older sockets can get weak and cause the pads to come in contact with the outer shell of the socket which is grounded. Newer after-market sockets have their own issue in that the pads are wider around, making it more likely that they will come into contact with the ground. The sockets are where you need to focus. If you have the stock system, start by taking one off of each bucket at a time to at least narrow down which side is giving you trouble. My experience is that the issue is more likely to be socket related than something in the switch.

[GeneBob]

What Bill G said.
The pads are domed and the contacts on the back of the bulbs are domed so it is easy to see a socket contact getting pushed to the side. I spent some time insulating the the back end of the pins where I could but there is not much you can do that won't interfere with the socket. Try chasing your short with the bulbs installed but the power off.
The opposite problem is the ground path from the headlight buckets to the frame. I soldered a wire to the headlight socket and ran it through the conduit to the frame to cure that one.
And Merry Christmas or whatever your Holiday may be.

[Fairlane514]

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Ok, thanks
I will check it out tomorrow.

[nkaminar]

In the back of my mind is a picture of a socket with a tube of stiff paper on the inside to insulate the pins from the grounded metal. I have no idea where this image comes from. It may be just my imagination.

[Bob Bidonde]

When I assembled my Victoria, I made a special effort to assure there are good grounds from the engine to the battery, from the body to the battery, from the frame to the battery, from the headlights to the battery, from the fenders to the battery, and especially from the stationary ignition point to the battery. There are several jumper wires in the car to assure low resistance grounds. Note that all of my grounds are from components to the battery.

[nkaminar]

One of the problems with Corvettes is that the fiberglass bodies are not electrically conductive, so all lights have to have a ground wire run.

[Fairlane514]

Prize goes to Bill G......Aftermarket sockets.....one of the contact nibs was touching the ID of the socket, a little dremel work and it seems to be working.

Thanks to everyone

[Fairlane514]

One other issue......The high beams come on at the 5 O'clock position and low beams at 4 O'clock. I turned the bulbs over but they do the same thing.

There are aftermarket bulb sockets installed by PO. They simply spliced the green/black to one of the aftermarket leads (both black wires) and the red/black to the other.

This a single bulb system with cowl lights. Its an early 29 with the 28 style headlights, if that matters.

[Fairlane514]

Ok, I went out tonight so I could see the bulb brightness better. I had to video it (no one else here), it appears they may be correct, kinda hard to tell.....I have the 32/50 bulbs CP 6 volt.

[Bill G]

Stock Model A headlight wires were black/red = low beam; black/green = high beam.


Check to make sure not reversed. However, from my experience 32 and 50 cp can be hard to tell the difference unless you are wearing some very dark sun glasses or welding goggles. The filaments should be horizontal; one stacked above the other. The way the reflector works, the high beam will be the lower filament and the low beam will be the higher filament.

[Fairlane514]

Yes, they are stacked one on top of each other.....the bulb is actually marked "top" for correct orientation

[katy]

However, from my experience 32 and 50 cp can be hard to tell the difference unless you are wearing some very dark sun glasses or welding goggles.

Parked 6' - 8' from a wall, you should be able to see where the high and low beam are at..