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Discussion Starter · #1 ·
My son's 1999 taurus with Duratec head lights, parking lights and dome light have developed a slight pulsing. It is at a pretty fast frequency and seems to get more pronounced as you rev the engine. It took me a while, but I have confirmed that his car does not have DRL lights. The pulsing if pretty faint. Checking out the lights in the daytime you can't really see it, you have to check in the dark. I would not worry about it too much except I don't want him to have problems at night away from home. I checked the voltage at the battery. 11.6 volts engine off, 14.3 volts and fairly steady engine on. The battery is new so the 11.6 actually bothers me a little, but the car has been sitting for about two weeks. I am thinking altenator but it is only about a year old . Any ideas on what to check. Thanks for any help.

Ed
 

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Discussion Starter · #2 ·
Took the car to two auto parts stores and had battery and alternator checked. Both check good, 12.5 volt engine off, 14.3 volts engine running. I took my meter and set it for AC to see if maybe some AC was not being filtered out and it is clean. Do not have DRL so it can't be the DRL module, even though the problem sounds exactly like that. Any ideas? I have checked all the grounds and wire runs as best I can and all look good. It acts like I am getting interference on my 12 volt line but I can't find anything.

Ed
 

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kenny, this site is about doing it yourself. Anybody can take their car to a shop, that's not the gist of the site.
 

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I think Kenny is a very subtle spammer. Look at the link in his sig.

It's PITA, but you may try cleaning and tightening the alternator electrical connections.
 

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Discussion Starter · #5 · (Edited)
Thanks guys Kenny is a real Joker. Funny thing is, I have one more thing to check and then I may find an automotive electrical shop to see if they will just diagnose the problem for me. Since the problem is with the lights, I am going to pull the headlight assembly and check with my meter there instead of at the battery terminals. I don't know if my meter has a fast enough response time to see the fluctuation on the 12 volt line. Otherwise, I will just have to wait until it gets worse or fails all the way. WJC, The connections at the alternator are good and tight. Unfortunately I think my alternator has some kind of problem even though it is charging okay. Not looking forward to that, I put this one in about a year ago and it is not fun as a lot of you know.

Ed
 

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@ Scout1 listen buddy ist of all you have to contact the one from where u get it... other wise if you need any technical support or in future you want a satisfactory stuff then write down this link www.autopartsway.com they deal all kinds of auto parts and provide the tech support.
 

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my 97 does it too when its cold. Its not an issue with the lights. Its the alternator. When it gets cold under load, there is some weird voltage regulator issue causing it to pulse. It may test OK on the bench warm, but if you put a scope on it when it cold and pulsing you can see the irregular waveform coming out of it. As long as the alternator wires are making good connection (including the small switching wire) another alternator is the solution as far as i can tell. bob
 

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Discussion Starter · #8 ·
Soundu,
That is pretty much what I thought. The altenator is pretty much self contained electrical system all in one. The problem is very minor now so I will live with it for now. The Duratec alternator is a pain to change.

Ed
 

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I had this same problem with a VW. It's usually caused by a bad diode. There is a pack of diodes that turn the a/c current in the alternator to dc before the voltage regulator. If one is allowing a/c in the line it will cause the problem you are having and still test as good.
 

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I had this same problem with a VW. It's usually caused by a bad diode. There is a pack of diodes that turn the a/c current in the alternator to dc before the voltage regulator. If one is allowing a/c in the line it will cause the problem you are having and still test as good.
Its strange mine only pulses when the outside temperature is cold in the winter. I am smelling bad solder joints or such. The diodes are a three phase full wave rectifier pack. I suppose if of the diodes had an intermittent connection, it could cause an issue. But it could be the internal voltage regulator too. Mine is doing it now with the cold temps. The voltage on the OBD2 scanner reads good 14.5V or so. But the scanner does not measure ripple voltage. If one of the diodes was opening up due to bad solder connection, it would put out an abnormal waveform on that phase of the three phase alternator. A oscilloscope would easily see what kind of wave form issue it is.
 
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