Car Fuses and Wiring

What causes the headlights dashlights radio and dome light to pulse with the engine running?


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2015-07-17 17:45:18
2015-07-17 17:45:18
1The same thing happened to my Buick Regal, and I had to replace the alternator. Eventually the car started cutting out when using the cruise control. 2I had the same problem with a 1991 Lincoln and a 1995 Lincoln, and it turned out to be the voltage regulator 3Sounds like your alternator is buggered mate. If possible, have a mechanic check the amount of volts being produced by your alternator. If your alternator is not putting out 13.5 to 14.2 volts, your voltage regulator MAY be bad. Most newer cars now have the voltage regulator built into the alternator, which means replacing [or overhauling] the alternator IF the regulator is bad. 4, Additional ConsiderationsWhile answers 1 through 3 are correct, alternator and/or regulator failure/defects ARE NOT the only cause of "pulsing," flickering, and/or dimming of vehicle lights.

There are probably several other causes, but I can only think of two others right now:

[1] This condition usually occurs when the engine is IDLING, and often is caused by the IDLE SPEED being TOO LOW.

[2] Slipping of the belt and/or pulley which drives the alternator can cause the same symptoms.

I suggest that you have a PROFESSIONAL AUTO ELECTRICAL TECHNICIAN, or any PROFESSIONAL [and well experienced] auto mechanic, check your problem out, and PROPERLY ADJUST the idle speed BEFORE any consideration of replacing an alternator and/or a voltage regulator.

If you simply replace these expensive components, AND THEY WERE NOT AT FAULT, then you will have WASTED a lot of money, AND you will STILL HAVE the problem, with more expense to come.

. Good luck.


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If you are parked with the motor running, engage the parking/emergency brake. Turn the ignition off and restart the engine. The daytime running lights should not be on.

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Auto headlights come on when it is dark. Daytime running lights are on whenever the engine is on. Both are optional equipment.

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no, using your headlights during the day, just uses power from the battery, and not from the engine, the battery is constantly being recharged , while the engine is running, any way,

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13.8 - 14.4 volts DC,13.82 with engine running and headlights on!

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