# Headlights dim when clutch is released



## JayZee (Jan 17, 2013)

Anyone else have this issue? I have a 2013 LT/RS Manual (obviously) with 1,850 miles. It's been doing this since day one.

When I'm stopped at a red light, and release the clutch, while in neutral, the lights dim for a split second about half way through the movement of the pedal. Sometimes it doesn't do it if you go too fast or slow.

The lights go noticeably dim for that split second, I'd say between 50-75% of their normal brightness.

I do not see anything change with the speed or sound of the engine when it happens. No bogging.

It doesn't really affect anything now, but I don't think it should be happening and don't want it to create other lasting electrical problems.

Any ideas?

Thanks


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## Aeroscout977 (Nov 25, 2010)

Probably just the added inertia of the first gear cluster on the rotating assembly. Given a moderately light flywheel the initial shock of that little bit of weight could lower the RPMs enough to have visible effects on the alternator's output.


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## JayZee (Jan 17, 2013)

But the thing is, I don't hear or see my RPM's change.


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## obermd (Mar 3, 2012)

That's not right. If you can reliably repeat it I'd take it in to your dealership and demonstrate this for them. Neither of my Cruzen do this.


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## jblackburn (Apr 14, 2012)

If you do that on my 2012, you see the RPMs rise up about 300. The headlights dim when I let the revs dip too low (in gear)


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## Chevy Customer Care (Oct 29, 2011)

@JayZee, under normal circumstances this would be covered under Bumper to Bumper warranty or the warranty that the diagnosis would fall under. If you would like assistance with setting an appointment, let us know.

Michelle, Chevrolet Customer Service assisting Stacy


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## Tjax (Sep 14, 2012)

Jay mine does the exact same thing. I've got a 2013 2LT Manual. I always assumed it was an "efficient" alternator that only kicked in the juice on an on demand basis. I was thinking maybe reading up on installing a large capacitor in the system to absorb the shock and keep an even power level until the alternator kicked in. If it is an issue though as Chevy customer service suggests then I'd much rather have it fixed. I agree it is annoying and makes the car feel cheap.

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## obermd (Mar 3, 2012)

jblackburn said:


> If you do that on my 2012, you see the RPMs rise up about 300. The headlights dim when I let the revs dip too low (in gear)
> 
> Sent from AutoGuide.com App


Headlights dimming when the engine speed dropping too low is because the alternator speed is tied directly to the engine speed. The battery's charge/discharge circuitry gets momentarilly confused when this happens and there is a major power drain such as headlights or A/C running.


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## obermd (Mar 3, 2012)

Just letting the clutch out, as long as you're keeping the engine speed constant, should not result in your headlights dimming.


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## JayZee (Jan 17, 2013)

obermd said:


> Just letting the clutch out, as long as you're keeping the engine speed constant, should not result in your headlights dimming.


The engine speed never drops. See OP. However, it does rise immediately after the release.

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## sciphi (Aug 26, 2011)

The engine computer will "blip" the throttle when the clutch is released while sitting in Neutral. The RPM's will bump up to about 900 RPM or so. Not sure why that happens. 

I'm also noticing those of us with 2012's don't see this happening, but the two posters with 2013 Cruzes do. We need another member with a 2013 Cruze to chime in whether it's a trait of the 2013's or not.

Whups, I saw it the other night after trying to re-create it. Seems normal to me.


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## obermd (Mar 3, 2012)

Just emailed my son with the 2013 ECO MT.


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## jxski07 (Feb 16, 2013)

I have the 2013 Cruz Eco and i can not recreate the headlights dimming at the low rpms.


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## sciphi (Aug 26, 2011)

I tried to re-create this the other night, and was successful. The headlights dimmed slightly every other time I suddenly released the clutch pedal with the car stopped, idling in neutral. It's probably the alternator not getting the signal in time to ramp up power, so the headlights dim a little.


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## Toocruze (Nov 26, 2017)

My 2015 does this. While in neutral when clutch is released headlights dim then the rpm bumps up then come back down


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## 17Hatch6MT (Dec 28, 2015)

I have a 2017 hatch with a manual. Mine does this. I thought it had to be normal, it is a brand-new car after all. I think what's happening is the ECM is shutting the alternator to reduce the load on the engine while the clutch is being engaged.


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