2002 Buick regal intermittent headlight pulsing

[Black92GS]

23 minutes ago, primergray said:

Maybe you'll want to look into something like this: https://www.summitracing.com/search/part-type/headlight-conversion-harnesses/product-line/united-pacific-headlight-relay-harness-kits

I don't think that would make a difference here.  It's not a headlight specific issue, it's the overall system voltage dropping momentarily and noticeably affecting incandescent/halogen light output and the audible tone from the blower. You can sort of duplicate it by leaving the lights on when you shut the car off. There is a slight but noticeable dim that takes place as the overall voltage drops from ~14 volts to ~12 volts. 

  

[mikeytcarter]

Okay sounds good, all of that makes sense! I am going to do the LED bulbs and im looking at a relay kit on ebay! I will update in a few weeks to see if I've gotten any better results.. thank you both for your time and insight. You guys have helped a lot!

[mikeytcarter]

@Black92GS those harnesses make it to where it plugs poeer straight from the battery rather than the fuse box. In theory if its hooked up like that it should not see a dip since the power wont have to go through the alternator first, right? Or am I mistaken 

Edited 2 hours ago by mikeytcarter

[Black92GS]

2 hours ago, mikeytcarter said:

@Black92GS those harnesses make it to where it plugs poeer straight from the battery rather than the fuse box. In theory if its hooked up like that it should not see a dip since the power wont have to go through the alternator first, right? Or am I mistaken 

More or less, yes. What matters is where the voltage drop is occurring.  If the voltage drop is only at the fuse box itself due to an undersized feed, but the battery is maintaining ~14 volts the entire time, then moving the lights to run directly off the battery will have a positive effect, since they will no longer be subject to the drops affecting the fuse box. 

However, if the voltage drop is due to the PCM briefly turning off the alternator, or the alternator not yet having caught up to the demand, that drop will be at the battery itself, so it effects everything in the vehicle. Moving the lights directly to the battery wouldn't have an effect there, since they would still be affected by the same drop. 

In the first video it occurred in conjunction with the AC compressor turning on, which I call normal operation for these cars.  My 2000 Regal did that and my parents 97 Lumina always did the same thing. The 2nd video was harder to tell, but it seemingly always happening around the same speed when coasting down makes me think that's when the car is coming out of it's deceleration fuel cut off, and the alternator output is briefly being cut to make the transition back to the IAC smoother. Older vehicles didn't experience this in the same manner, as the alternators weren't controlled by the PCM. Newer vehicles with electronic throttle bodies don't seem to experience this either as the PCM has full control over the throttle itself. I really don't think there is an issue that needs solving.  If you want to keep the headlights from showing the effects, you could look at switching to LEDs. The LED chips typically run at less than 12 volts, so they have a voltage regulator to keep things in check. This would prevent them from dimming whenever the vehicle voltage fluctuates slightly. 

Also, ignore what I was mentioning earlier about the ABS. The ABS kicking in will cause the lights to dim briefly due to the load, but after seeing the driving video, i don't think that's what's happening here.  

 

[mikeytcarter]

Okay cool! All great info. Ill report back in a couple of weeks! Gonna do the LED and if that doesnt work try the harness! 

[mikeytcarter]

And also im theory if it was at the battery then wouldn't I also see my dash lights or anything else inside dim at the same time?