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EFV-8 Club Forum / General Ford Discussion / whimpy headlights

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Posted By Discussion Topic: whimpy headlights -- page: 1 2     GK1918 10-25-2025 @ 7:01 AM reply profile send p.m. New Member Posts: 134 Joined: Aug 2016 Keep this in mind: When 6 volt vehicles were king of the road their lights were bright as bright can be : So as time flew by then got dimmer & dimmer. Then the after market relays were good sellers, another band aid. Then the weekend electrician made matters even worse. We have to start from scratch wires must be thicker correct soldered terminals clean everything. Example my fuel gauge went to 0. grounded sender still zero the gauge is getting power. Bought a new gauge but before I installed it I took a good look at wiring to the rear and found one wire connection all green, added a piece to where wire was good bingo gauge works that cost 40 bucks for a new gauge thats OK more new stock...... TomO 10-24-2025 @ 8:43 AM reply profile send p.m. Senior Posts: 7385 Joined: Oct 2009 To check your ground, connect your + lead of the voltmeter to the POS terminal of the battery and the common lead to the grounding lead of the passenger side headlight plug. Turn on the headlights and read the volt meter. The reading should be 0.1V or less. To check your head light switch, connect the meter common lead to the NEG battery post, turn on the headlights and probe the output of the light switch. The reading should be 0.1 Volts for a very good switch and above 0.2 for a dirty switch. The 1940 switches feel sloppy in their operation, but they are very durable. When you tested the voltage at the headlights, what was your battery voltage? A fully charged battery should read above 6.0 volts with the lights on. Tom Barney 10-24-2025 @ 3:25 AM reply profile send p.m. New Member Posts: 127 Joined: Nov 2015 TRJ & Jay, Thank you for your input and ideas. I'm beginning to think my ground(s) aren't as good as I thought. A new switch may be a good idea; the original seems quite anemic. I'm looking forward to measuring the voltage at the ground terminal. Thank you. Barney JayChicago 10-23-2025 @ 12:01 PM reply profile send p.m. Senior Posts: 555 Joined: Jan 2016 "With the high beam wires disconnected at the dimmer switch...I measure 5.9 V at the headlights' low beam terminal. However, I measure 2.3 V at the high beam terminals.?.?" Assuming you are taking readings with the bulb connected / current running thru the bulb, then that sounds like poor ground to me. If the low beam current cannot easily drain to ground, some voltage will build on the ground side of the bulb and back-feed into the high beam supply side. I know you have new ground wires. Is there a clean path from the bulb to the new ground wire? Can you measure voltage on the bulb's ground terminal while light on? Should be near zero if easily dumping to ground as it should. This message was edited by JayChicago on 10-23-25 @ 12:30 PM trjford8 10-23-2025 @ 8:27 AM reply profile send p.m. Senior Posts: 4352 Joined: Oct 2009 I would use 14 ga. wire .Also if you think it is the switch you can use a later model switch and you can put the '40 knob on the switch. Barney 10-23-2025 @ 3:50 AM reply profile send p.m. New Member Posts: 127 Joined: Nov 2015 Thank you very much to Carcrazy, Paul, Trj, TomO and FordV8 for your responses With the high beam wires disconnected at the dimmer switch and with engine not running, I measure 5.9 V at the headlights' low beam terminal. However, I measure 2.3 V at the high beam terminals.?.? Seems like there may be a partial short inside the sealed beam; this seems it would be very unlikely. I agree about grounding; I have very good grounds; each light, front and back, has it's own individual ground wire. I'm not a fan of the original light switch; feels like poor internal connections. I'm contemplating utilizing a toggle switch for headlights and a second toggle switch for the taillights. Lastly, I'm utilizing 16 gauge wire for the headlights; heavy enough? Thanks again for all your advise. Barney fordv8j 10-22-2025 @ 4:28 PM reply profile send p.m. New Member Posts: 193 Joined: Jan 2015 I put 6v sealed beama on our 38; they were dim ,I ran a heavy wire from hot side of selenoid, through a fuse to a toggle wsitch under dash, then th the hot post on dimmer switch; turn lights on with headlight switch, flip toggle switch on...they get bright TomO 10-22-2025 @ 1:58 PM reply profile send p.m. Senior Posts: 7385 Joined: Oct 2009 The most common cause of dim lights is low voltage to the bulbs. With the engine off you should have at least 6Volts at the bulb. If you do, then the second most common problem is old bulbs. Try replacing your headlight bulbs. If the voltage is low, operate your dimmer switch many time to clean the contacts and then recheck the voltage. If that doesn't work, you are going to have to do a voltage drop test to find out where the voltage is being lost. This test is done by connecting the COM lead of your voltmeter to the NEG post of the battery and then probing connections with the + lead of the meter. The rule of thumb is that you will lose 0.1V at each connection or switch. Anything more than that is a ba connection. Tom trjford8 10-22-2025 @ 12:15 PM reply profile send p.m. Senior Posts: 4352 Joined: Oct 2009 I agree with Paul on this one. Check all the grounds and make sure they are clean. Grounding on a 6 volt system is critical pauls39coupe 10-22-2025 @ 10:22 AM reply profile send p.m. Member Posts: 247 Joined: Jul 2014 Check the ground side of the headlight wiring to be sure you have a clean and shiny connection. Also check the body grounds and the dimmer switch connections.

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