head lights dimming at low rpm

[TurboGrayLZ]

I realize this could be a battery or alternator issue. But Has anyone else noticed their lights diming when coming to stop and then taking off again. I have a manual and my rpms have been getting down to around 500 at idle. Pretty low so that could be it. Anyways just looking for some feed back. Thanks

 

[ChrisJ]

I wouldn't say battery I would guess alternator.
However I've never seen my 1.4T idle less than around 750 which makes me thing you have a problem other than an alternator or charging system in general.

I'm sure if I force mine down to 500 the headlights will dim.

 

[ahtoxa]

Some minor dimming is normal when the RPMs drop a little. I've noticed that on every car I've ever owned. 500 RPM is a bit low. I thing normal idle for manuals is 650-800 range or thereabouts.

 

[ChrisJ]

Some minor dimming is normal when the RPMs drop a little. I've noticed that on every car I've ever owned. 500 RPM is a bit low. I thing normal idle for manuals is 650-800 range or thereabouts.

Agreed to an extent.
Typically you shouldn't see much if any of a drop under light load. If your heater or A\C is on #3 or #4 then you probably will see them dim some. My Sonic doesn't dim at idle but I usually run my fan on #1 or #2.

Of course depending on how I clutch they may dim but not just sitting there idling. I've owned many cars that had alternators drop off big time at idle and it was usually a problem with the alternator. My 87 GP had the problem and I went through 4 or 5 rebuilts until I finally got one with good output at idle. I think I went through 2 rebuilts on my 92 pickup trying to get another good one. What I had learned was rebuilt alts often suck. I tried rebuilding my own and finding parts locally was impossible. I had a blown diode in the original from the truck.

 

[sx sonic]

At 500 rpm the lights will dim, shouldn't be idling that low.

 

[Chevrolet Customer Care]

I realize this could be a battery or alternator issue. But Has anyone else noticed their lights diming when coming to stop and then taking off again. I have a manual and my rpms have been getting down to around 500 at idle. Pretty low so that could be it. Anyways just looking for some feed back. Thanks

Hey TurboGray,

Have you talked to your dealership about this concern? If you need help setting up an appointment we're happy to help. Feel free to private message us your name, contact information, VIN, current mileage, and preferred dealership.

Sincerely,

Jonathan A.
Chevrolet Customer Care

 

[TurboGrayLZ]

Thanks for the input. I was thinking the same things. I have not been to the dealer. I need too though. Driving 500 to 1k miles a week right now just havent had the time. My a/c running it runs around 800 rpm but with it off it will drop to 500 and kinds lope alittle. Its been a bit#* taking off in ive actually killed the damn thing several times lately. I will keep yall posted think I will take it in thursday.

 

[Preloader]

All good info above, just gonna add to it.

Mine dims often. Usually as I'm coming to a stop and the idle dips until it settles back up. It doesn't hurt anything, but is prolly a nuisance to the car in front of me.

If it were any worse, I'd pursue havin my idle set a tad higher. It sounds like yours is at that point. I'd see about getting it raised.

 

[attrapereves]

Happens to me if I let off the clutch a little too fast with no gas, almost making the car stall. Just for a second though. I wouldn't be worried.

 

[severous01]

adjust your idle up a bit. every car with a manual dips down to 600 rpm or so and lights will dim just a bit. it's normal, automatics tend to stay around the 750 range which is more than enough for the full 14.4v the alternator can make.