The Stovebolt Site Forums The Shop Area The Electrical Bay Grounding issue with head lights

Just hooked up a turn signal to a brand new wiring harness which works fine. But the high beam indicator light is on all the time. Dimmer when low beams are on.
Anyway I've tested the hi/low switch and it reads fine. Doesn't appear to be stray current in the lighting under the dash.

I've also tested the junction terminals up front and they are fine as well. No jumping terminal blocks when wires to headlights are disconnected.

I've tested the light pigtails, they are fine. It's when power is touched to the headlight that it crosses over to the other filament and backfeeds the indicator light on the high circuit. I can almost get the indicator light to go out when I ad an extra grounding clamp.

So what is going on? Everything has nice new paint on the headlight bucket and stainless bolts throughout. The grounds are new wires with tight fittings. I've tried other headlights but I can never get either high or low by themselves.

Any suggestions appreciated.

As stated here many time, make sure grounds are to bare metal, not to painted surface. May be no help, but that's all I got.

It's a new to me vehicle so I'm still sorting a few things out. I'll double check all the grounding straps and maybe clean up the bolts that the headlight ground wires are attached to.

I find it odd that putting extra jumpers on the grounds directly to ground straps didn't have much effect.

maybe the 'extra jumpers' you're adding are still to painted metal? SS bolts aren't as good conductors, make sure lock washers are 'digging in' to the bolt and sheet metal

Bill

When grounding electrical systems or components I use star washers, they will dig into metal and give a good ground. Pat

Back at it today with no luck. Tried many scenarios. Put extra grounds to the headlights with good grounding bolts to bare metal.

Also completely bypassed the hi/lo switch. Here I just connected the hot to the low beam wire and did not connect the high beam circuit. Guess what, the high beam indicator lights up! Also the volt meter showed the high and low beams drawing 4.5 and 2.5 amps. Again the high circuit not physically energized.

Can the rear lighting circuit interfere with the front? I don't see how it could looking at the wire setup. Again, the parking lights which are on a different dash switch and the new turn signal setup all work without a hitch. Uniform brightness in all settings.

The only thing I have not done is clean the junction boxes for the front lights on the fender well. All though I don't see that being an issue since I have power to the lights.

I wonder if wires got crossed in the harness under the "nice" braiding?

use a meter to check wire routing, very unlikely wires are 'crossed' in the harness, but entirely possible some got hooked to the wrong places

Bill

I don't know what year we are talking about here but I am going to assume that these are sealed beam lights. Now, each headlight has three terminals, high, low and common. If you have them interchanged, it will produce your symptoms. On my 51, the headlights go through a junction strip on the fender and it is possible to mix up or interchange the connections there.

It is a 1941 with sealed beam 6volt lights. It has the 3 prong terminal. The lines match the terminals in each light. The ground/common is in the middle/top spot at a horizontal.

Update:

Thanks for the suggestion on the end plug. Had to flatten a brad nail to disconnect the lines to the terminal. Discovered that the PO had them all mixed up. What threw me was the nicely color coded lines and paint dabs on the connector supposedly matching the right line to the right slot.

Oh well. The manual didn't have anything on the correct slots either but it now works! Thanks.