DIm Headlights

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    Is it normal for the headlights on these cars to be dim? Even on high beam they are not very bright. Searching for light!

    Peter C. King


    I’d like to tell Lucas Prince of Darkness jokes at this point, but TD kit car electrics aren’t British. If the engine is in the back they are German. If it’s in the front, they are American.   

    Start with simple stuff first.

    Look at the headlights with the switch off. Are they darker in the center? They could be old and almost burned out. Plug in another headlgith. It doesn’t have to fit the bucket. Is it brighter? buy headlights. Don’t go nuts with Halogens. You have a small alternator/generator. It can’t handle flamethrowers.  

    Are the headlights the only dim bulbs? Dashboard? Tail Lights? If so then your problem is with the headlight circuit. If not then your problem is elsewhere in the charging system.

    Is there water in the battery? Low water can cause low voltage.

    Unplug and plug the connectors between the headlights and as far into the wiring harness as you can go. Find the dimmer switch and check the connectors there. Ditto for the light switch. Check for corrosion under the battery cables.

    Start the engine. Turn on the lights. Aim the car at a wall. Look at the brightness as you raise the revs. Don’t float the valves. A high idle will do. Did the headlights grow brighter? Did any lights grow brighter? If so, your alternator is OK. If not, the alternator may be dead. Do you have to charge the battery often? Do the lights start out OK and grow dimmer as you drive? That’s another sign that the electrons in the alternator aren’t holding hands anymore.   

    OK. the alternator passed the test. The headlights are still dim. Use a voltmeter to read the voltage at the battery. Then read the voltage at the headlight. It’s down? Check it at other lights. It’s OK? The one place you cannot see corrosion is inside the dimmer switch. Check the voltage on either side of the switch. If it’s different, buy a switch. It’s OK? Check the voltage at the light switch. OK? Check for corrosion on the fuses. Something is cutting voltage to the headlights. Once you’ve eliminated the lights, bettery and alternator it’s a corroded terminal or switch. 

    You don’t know how to use a voltmeter? Harbor Freight has a digital unit on sale for $3. It comes with directions. It’s the handiest tool in your toolbox when you are chasing electrical gremlins.

    You can still tell Lucas Prince of Darkness jokes.

    English electrics don’t use electricity. They use smoke. when you let the smoke out of the wires, nothing works.

    Why do the Brits drink warm beer? Lucas makes refrigerators.

    Lucas invented the intermittent wiper. They are still working on the continuously on wiper.  


    Larry Murphy


     Great advice from BDriver. Also be sure to check the grounds. On these fiberglass cars ,each light or other accessary must also have a ground wire connecting to the metal chassis .

    Peter C. King



    I knew I’d forgotten something. Everything on a fibeglass car is grounded to the frame. It’s on the bottom of the car. Grounds corrode even faster than the high connectors.

    The Voltmeter can be handy for checking grounds. Set the gauge for resistance (Ohms) and probe the ground side of the light and the frame. Having to use increasingly higher Ohms settings to receive a reading says that you have to find and clean that ground.

    The good news is that by the time jhbyrd has his car sorted out he will be intimately familiar with the unnatural acts the original builder went through to assemble it the first time. He will be at a show when his right headlight will start acting erratic. He will mutter under his breath about grounds, put a “Lucas Prince of Darkness” pin on his hat, select a medium size Phillips screwdriver from his toolbag, lift the hood, hand his coat to a fair damsel, roll up his right sleeve, insert his arm behind the engine, wiggle a screw in the depths of the engine compartment by feel and the light will shine brightly once again. Instant GuruHood! The crowd cheers in admiration. The fair damsel is optional.  



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