lights dim when i step on brakes and slow down

[Trunks]

Why is it that when i step on my breaks and slow down my lights dim and my rpm's drop (to like 500 or 600) then after i stop the lights go back to the way they should be and sometimes the RPM's will go up but sometimes they stay at 500-600

[hockeyman]

Sounds like your IAC Sensor is starting to go.
Get it at Autozone for $26.

-Marc

[Dominic]

Its the stupid way the voltage regulator works in these cars. Some are worse than others, like my old Firebird.

My new Camaro doesnt seem to have this issue really, but the firebird did from day 1.

[DravensBird02]

(GAWD I love this site!) I haven't asked or posted any tech questions before but I am starting to notice a few things wierd about my car and you guys already have asked them! It's a relief sorta, to know others are having the same problems as me.

I was curious about the lights dimming too. My 93 bird didn't do that. But this one I have now, does. I'll hit the brake and the headlights will dim out for a bit and come back up. My volt meter drops a bit too.

Is this normal?

[twofaced]

This happens to my car as well, been doing it since the day I drove off the lot, with 51 miles on it. Dealer service department says, that the way the car is???? OK, lol. Anyways, seems like it is the electrical system or the way it set up.

[raider3.4]

Mine does it some times.

[Camaro_SLP]

After re-reading your problems..I don't know.

I didn't have those problems.

[ September 29, 2003: Message edited by: Camaro_SLP ]</p>

[ka50]

Mine does the same thing. It kinda fluctuates between 500 to 800 few times, then brings to normal. I believe it's computer finding ideal fuel-air ratios.

[Guardsman]

I'm almost positive it's the voltage regulator. Our cars use a generator (uses an electromagnet instead of a natural magnet to create the magnetic field, and the regulator uses that to control the voltage generated.
The generator puts out ~14V, your battery puts out 12. So, when the regulator shuts the generator off, the system drops to 12V.
Also, the PCM will test the EGR valve right around the same time (below 1500 rpm, no throttle, coasting), so it may be drawing on the system.
Basically, it's an annoying little quirk of the system.