polo1134

I just noticed my headlights flicker or dim slightly when I press the brake pedal or when I have my turn signals going. The headlights seem to flicker in time with the blinkers.

Anyone know why this would be happening? I just replaced the headlight switch (multi-function switch) and added the ipod-to-car. The flicker did not show up right away after those changes so I'm hoping it does not have to do with those parts. Has this happened to anyone else's car?

My car is a 2000 M6. Any help would be appreciated. Thanks.

65GGvert

It's really not unusual. They'll dim with your power window switch too.

blacksedan87

Make sure your battery terminals are snug - not overtightened!

1sickz51vette

I think it happens on all C5's, you have have just noticed it... Mine does it too, really bad when you press the window up button!

mtndv8

Might check your grounds, too, if you can, just to be sure...

polo1134

I will check the battery tomorrow. I have owned this car for a little under 2 years and the headlights have never flickered before. I'm just a little concerned that this is not a prelude to a bigger problem.

Thanks for your suggestions so far. Anyone else with any ideas?

richard emmanuel

The bigger problem would be when the headlights flicker to the excat same sequence as the turn signal and you will have whats called double blink amenima. Seriously my c3 does it a lot and the c5 a little. I am sure its a weak ground somewhere or perhaps the items you added arent grounded enough. I wonder if the lights get brighter as you rev up more?

DeeGee

It shouldn't happen

I agree with the things to check:

Check the battery. To check your battery voltage, do not read the DIC when the car is off. The voltmeter is designed to measure alternator output when the car is running. It will always measure an inaccurately low voltage on the battery when the car is off. Anything from 11.0-11.9 is not abnormal in this mode. With the engine on, the voltmeter should show between 13V and 14.5V. A better reading can be measured at the battery terminals. Use a digital multi meter if you can. A fully charged battery measures 12.66 V and a fully discharged battery measures 11.86 V.

For any of these methods, you must first fully charge the battery and then remove the surface charge. If the battery has been sitting at least several hours (I prefer at least 12 hours) you may begin testing. To remove surface charge the battery must be discharged for several minutes. Using a headlight (high beam) will do the trick. After turning off the light you are ready to test the battery.
State of Charge Specific Gravity Voltage12V
100% 1.265 12.7
75% 1.225 12.4
50% 1.190 12.2
25% 1.155 12.0
Discharged 1.120 11.9


Alternatively, Autozone will do an on load test for you. If your car's not a DD and you don't use a battery tender the C5 is hard on batteries and it may be run down. An overnight charge will help. This would be my best bet.

If that's not it check the battery terminals. Clean them up and retighten them. Reattach the positive cable and torque to 15 N-m (11 lb ft). Reattach the negative cable and torque to 16 N-m (12 lb ft). Flickering headlights over bumps is normally the symptom here.


Failing that move on to the grounds. The headlights ground at the point on top of the frame behind the passenger headlight. The rear lights ground at G401. The fact that 2 grounds are in play makes me think it might not be that but its possible.

I see you replaced the headlight switch but it could still be a switch issue. The hazard switch has a number of lighting functions incorporated and is notoriously unreliable.

65GGvert

You can chase this all you want, but I have yet to own or ride in a C5 that the headlights didn't dim a little when you press the brake or use the power window switch. If the light intensity changes when you hit a bump, that's different, but that is not what you describe. Try someone else's C5 and stop worrying.

DeeGee

Interesting but mine don't

I wonder if its something to do with the H4 bulbs in the Euro Lights?