LED headlight lamps
 

Here is a puzzle. I bought 6 Volt LED headlight bulbs for my 1930 Model A pickup. I replaced the passenger side with the new LED Bulb... it worked (it was much brighter) Then, when I removed the incandescent bulb on the drivers side... the passenger light went out. I then installed the LED bulb on the drivers side headlight. Neither bulb would light up. I installed the old incandescent bulb back in the drivers side headlight, both lights worked, the LED Bulb on the passenger side & the incandescent bulb on the drivers side. Why would the passenger side bulb only work when the drivers side had the incandescent bulb installed? I replaced the 4 taillight bulbs with LED bulbs... they all worked. (again much brighter).... another question (I'm a Model A newbie) on the headlights, there is the high/Low beam bulb in the middle, what is the bulb below that? Parking light? No matter what position the switch is in, these bottom bulbs will not come on. Yet another question concerning the taillights. There is a top bulb with a larger lens surface area & a bottom bulb. The way I got the pickup is the top is the running lights & bottom is the stop lights... is this correctly wired?

Re: LED headlight lamps
 

Re: LED headlight lamps
 

Yup!

Re: LED headlight lamps
 

I hate electrical problems. The last one I chased was for my headlights too. When turning on the low beams my parking lights came on too. Traced down to the connection socket/pins for the conduit connection. Two pins were touching. Check all connections and remember these connections are spring loaded so they may be in a different position.

Also I believe the bulb that you say is below the center bulb should be above the center bulb. So your reflectors need to be rotated 180 degrees. They are the parking lights. The switch on the steering column is turned clockwise (one position) from the off position for the parking lights.

Re: LED headlight lamps
 

Your headlight reflectors are upside down, as Grier notes. The brake light (green wire) should be 21CP through the upper amber lens, running/park lamp (black wire) 6CP through the lower red lens. LED bulbs of course pretty much however bright you want. Bright red LED will shine RED through the amber lens, which other drivers recognize better.

Re: LED headlight lamps
 

This link shows the original wiring for the Model A and some common modifications that are made. Check to see if the wiring is correct for your car and check for proper grounds as talked about above. Check for bad connections and bad wires too. The stop light is the larger one at the top. It is sometimes amber rather than red.

https://cedarcreekas.org/TechTopics/...rn_Signals.pdf