Headlights go dim

[Tribe21]

Headlights and interior lights flash dim then go back when ac compressor cycles only when im coming to a stop. If im driving at speed then no problems or if no ac is on. New battery, alternator, and serp belt 6 months ago. Was doing the same thing right before these were replaced. Could it be the bearings in the compressor or is it normal?

Car in question is 03 cavalier.

 

[901Memphis]

I had a rusty ground cause that on my Buick

 

[tomcat27]

while it certainly would not hurt to check all battery and ground connections, I would say that behavior is likely very normal.

 

[HangFire]

Compare battery voltage to connector voltage, with engine off and lights on... same meter.

Check ohms between headlight ground connector and chassis.

 

[Kuato]

Originally Posted By: tomcat27
while it certainly would not hurt to check all battery and ground connections, I would say that behavior is likely very normal.


https://www.youtube.com/watch?v=r5X8qDDMC-o


Sorry, not normal. Loose connection, bad voltage regulation, weak battery or alternator all could cause the issue.

I'd suggest having both the battery and alternator checked first.

 

[SwampSurvivor]

Ground issue somewhere.

I have recently replaced the alternator and battery on my Jeep. The headlights would always flicker when I would first hit the turn signals - still do.

 

[Silverado12]

I have a 1999 Jeep that does this and I had a different 1999 Jeep I bought new and does the same. I say it's normal if it's only barely noticeable. Your symptoms are different. FWIW my 2002 Cavalier doesn't do it at all. I would start with the basics like the others said. If terminals are questionable, replace them, then check battery.

 

[The_Jeff]

Cavaliers have a crummy ground on the battery tray. The main ground wire drops from the negative terminal to this bolt (which will snap thanks to rust) then goes off to the engine block.

Rather than muck with all this, I'd rig up a 10 ga ground wire between the engine and, oh, maybe a strut mounting bolt on the chassis.

 

[HerrStig]

Originally Posted By: Tribe21
Headlights and interior lights flash dim then go back when ac compressor cycles only when im coming to a stop. If im driving at speed then no problems or if no ac is on. New battery, alternator, and serp belt 6 months ago. Was doing the same thing right before these were replaced. Could it be the bearings in the compressor or is it normal?

Car in question is 03 cavalier.
Compressors don't draw much but the electric cooling fans and the interior fan do. Check for a bad ground.

 

[Nick1994]

I agree with a bad ground. My mom's 2003 Buick had an issue with the headlights being dim this year and it was doing whacky things. Was just a loose ground wire by the driver's headlight.

 

[gathermewool]

OP, let us know what you find out, if anything.

I noticed the same thing happens in our Civic: the headlights will quickly dim and return to normal when the A/C compressor first kicks on. I noticed it, but haven't yet paid attention to whether it only occurs at lower RPM, such as while crusing at lower vehicle speeds or while idling.

If my windshield and windows aren't icy or fogging over, I typically wait until after I get up to speed on the local road I take to work (~35 MPH for an extended period.) There aren't many lights where I live, so the dimming would probably be less noticeable with more ambient light.

If I have time I'll poke around and start my own thread if I figure anything out.

 

[Tribe21]

Finally got around to checking out possible grounding issues and sure enough the battery tray ground off the negative post was rusted. Pulled battery out and the tray was rusted in multiple spots not just at the ground bolt. Luckily it was just surface rust so cleaned everything up and primed and painted the tray (not ground bolt). Put all back together and checked and cleaned all other grounds just to make sure nothing else was rusted and all were clean. It runs better now than it ever has. The tray was painted from the factory under the bolt. Thanks for all the suggestions.