Lights pulsating in morning...

Messages
1,653
Location
San Antonio, Texas
Sorry if this is in the wrong forum, but I don't think this is a lighting issue, I think it's a mechanical one. On my 06 Honda Civic EX 2-dr - I replaced my battery about 2 wks ago. Car sat for about 5 days, then yesterday I started it up and noticed that the headlights and interior dome light would "pulsate". I never noticed this before. It seems to go away after about 20 mins of driving. It also happened this morning. What do you guys think? Weak battery? one rectifier gone on the alternator? Thanks! smile
 
Messages
36,515
Location
ME
Sounds to me like the alternator field control got confused. This stuff is computerized now. However, it could be something stupid like a loose terminal. You probably wouldn't notice your lights pulsating from a bad diode in the alt-- too high a frequency. You'd hear it in the radio though. Throw a voltmeter on it with it running and not.
 
Messages
19,479
Location
Chicago Area
Clean all cables - BOTH ends [and where they seat]. This is excellent to do no matter what the problem is. But a bad alternator [maybe diode] is a strong possibility.
 
Messages
408
Location
Minnesota
Had the same problem on my 2001 civic EX. It was my alternator going bad. I made the mistake of buying a rebuilt at A-zone and am on my 4th in the last 2 years. Hopefully O reilly alternators are better. I am getting good at changing them though.
 
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