'60 Convertible Headlight Switch

[jopizz]

You have two wires that go to the left parking light, green-white is the turn signal wire and black-yellow is the parking light wire. I would check where they come through the driver side firewall and the parking light plug itself. They don't meet anywhere else unless they are shorted inside the harness.

John

[simplyconnected]

...That is typical of a bad ground at the Lamp Socket.
Check your grounds at the light sockets!!!

Did you do this?
Did you use a jumper wire connected to power and WATCH both LH front filaments, individually and then together?

If you don't have a big mirror, find a helper.

Are either lights dim?

Understand that both filaments ARE tied together and that electricity takes the path of LEAST resistance. That means, If you let the lamp socket hang ungrounded, the Parking Light current will feed back into the turn signal wire and go to the dash lamp that IS grounded.

Another problem can be inside the socket where the lamp shell doesn't make good contact with the lamp holder. Look inside. Is it green and nasty?

Use sound troubleshooting practices which include ALL of your senses. Your entire lighting system can be tested with the help of two simple tools; a 12 volt test light and a jumper wire with alligator clips on both ends.

Light bulbs are wonderful loads because they show a visual indication of the current passing through. LED test lights are NOT a good troubleshooting tool because they draw no load.

Your front lamp holders are in the weather and susceptible to corrosion. Lamp holders in modern cars are made of plastic and they have their own ground wire (3-wires in each socket). They do not depend on body ground. This should tell you something about the evolution in technology. If your lamp housing is poorly grounded, run a separate copper wire to a good ground or better yet, to the battery. - Dave