prodjay10

2004 Honda Civic LX Coupe 1.7L Automatic

A while back the headlight and dome light started pulsating. I didn't do anything about it until the alternator died. I had a friend fix it. One of the brushes fell apart so he replaced it. Took it to Vatozone to test. Passed their test.

Car works fine for a while. I don't see any pulsating. But battery died right away too. So I get a new battery. After new battery is installed the lights pulsate again. It does this on and off. I can't seem to figure out what triggers it.

Soon after the turn signals stop working intermittently. Same with the dome light. Sometimes it doesn't want to work.

Anyone ever have this issue?

Any help would be appreciated.

toyomatt84

iTrader: (1)

You may have a faulty multiplexer.

prodjay10

Is that the one next to the flux capacitor? jk

How would I begin to diagnose?

toyomatt84

iTrader: (1)

https://honda-tech.com/honda-civic-2...oblem-3234890/

Former User

Does the charging system warning light in the cluster sometimes turn on while you are driving?

prodjay10

The warning light doesn't come on. It did when the alternator went out.

Former User

Turn the key from OFF to ON(II) without starting the engine. Does the charging system warning light in the cluster turn on and stay on? If so, start the engine. Does the light turn off?

prodjay10

The charge light comes on with key on engine off. And turns off after turning on engine.

Former User

Check the G201 and G501 grounds. They are both shared by the Multiplexer and the turn signals.

prodjay10

G201 is behind the radio and G501 is on behind the right headlight mounted to the inside of the fender correct?

Just recently the cruise control and turn signals stopped working altogether.

nikkarocky

I know you said you replaced the alternator but the rectifier might be going out. I had the same issues with my gfs car and replaced it with a denso alt and everything is good as new now

prodjay10

I didn't replace alternator. I had it fixed by having one of the brushes replaced. The alternator has come to mind. I wonder if the test they perform at the auto parts store with the alternator in the car will tell if the rectifier is bad?

prodjay10

I went to autozone today. They tested alternator in the car. According to them, it works.

RonJ@HT, I'm having a hard time finding the location of those grounds. Do you happen to know where they are?

Former User

prodjay10

Turns out the turn signals weren't working because of the turn signal relay. Swapped that out and the turn signals work.

Now to track down the other issues.

Honda_Dude84

ur alternators bad mine did the same thing, it charged barely at 12.2 to 12.4 volts and the ripple current was real bad due to a failing diode / rectifier. U should get the alternator replaced promptly. because I also had a new battery like u and my alternator was just sending enough "spikes" to keep it going and now I have to get both a new battery as well as an alternator cause the old alternator fried the cells.

prodjay10

Where did you get your alternator?

I'm not sure if I should go with new, used, or rebuilt. The used would hopefully be original parts which would be better quality, but may have the same issue as mine.

Djratrap

Are you running an aftermarket header?

toyomatt84

iTrader: (1)

What does that have to do with this topic?

prodjay10

Stock header...

Djratrap

The crappy aftermarket headers (megan specifically) tend to pinch the secondary o2 sensor wires (grounding them) causing all types of shorts. I've personally had it happen to my old 7th gen. Fried my ecu and shorted a bunch of stuff.

prodjay10

I replaced alternator with a used one from a junk yard. Looks like the issue is fixed. No more pulsating.