| PeterFord | -- 04-09-2012 @ 8:49 AM |
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I have a 51 Ford F1 pickup. The headlights fluxuate in brightness as I drive. Can't notice it at idle, but with increased revs the headlights fluxuate. I have a new Alternator. New dimmer switch. The other light that fluxuates is the heater switch light. Seems to me to be a grounding problem but I do not know where to start to find it. Peter
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| supereal | -- 04-09-2012 @ 10:14 AM |
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If it is a grounding problem that affects more than one component, suspect the battery ground cable. Check the ends to be sure they are clean and bright, and that the connection to the fire wall is likewise. Be sure that there is a ground cable between that point and the engine. The voltage regulator in the alternator must have a good ground to prevent fluctuation. When you are satisfied that the grounds are good, check the "hot" battery cable connections, particul;arly the connection between the battery terminal clamp and the cable. Acid can, and does, infiltrate that area, causing a high resistance connection. Using a voltmeter, check the various parts of the system, starting at the battery, working toward the alternator, to see if there is a varying voltage drop at any point, including the output terminal of the alternator while the engine is running fast enough to turn the alternator on. If all check out, you may have a bad diode in the trio of the alternator, not a rare problem.
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| 51f1 | -- 04-09-2012 @ 1:24 PM |
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Do you have a alternator or a generator? I guess if it's a grounding problem, it really doesn't matter. Always check the grounds on an old vehicle. I recently helped a friend diagnose a problem with his battery not charging on a '50 F-1. The first thing I suggested he do was check and clean all of his ground connections between the battery, regulator and generator. He did that, and the battery started charging. Richard
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| TomO | -- 04-10-2012 @ 7:16 AM |
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I agree with Supereal that a bad diode in the alternator will cause this along with anything else that will cause the voltage to vary. Poor grounding of the lights, will usually show up as dim lights and they will stay dim until a ground is found, usually when you hit a bump that will jar the connection. Connect your voltmeter from the output terminal of the alternator to engine ground and then raise the engine rpms to about 2000 rpms. The voltage should reach the charging voltage (7.2 V or 14.6 V for 12 volt) and stay there. Tom
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| PeterFord | -- 04-10-2012 @ 7:49 PM |
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you were right. I cleaned all the main battery ground contact points. Voila! Thanks
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