car lights dim and funny idle

[donovandishon]

my 2000 alero idles to about 1500 the drops to 500 rpms and when the idle goes to 500 the headlights and interior lights dim and every now and then it dies....only does this when sitting still does fine when driving

[heineck]

check ur alternator... go get it tested. most likely the culprit

[Thewolf]

Might be your TPS.

[lord2heart]

clean your IAC

[Lucalare]

Agreed on the IAC, but check on that alternator as well, even at 500 RPMs your lights shouldn't dim, nor should the car die from lack of power. My old truck(which I sold today) would run about 250 RPMs at idle when it was warm with all electronics going and the lights were still bright.

[cherrington17]

get an overdrive pulley for your alt.

[clutch1]

edit: ninja double post.

[clutch1]

Vacuum leak almost 100%, that's how they do.
Smoke the manifold, repair any leaks found.

The dimming lights is just a product of the erratic idle, mot likely. Fix the idle, FIRST, then diagnose the lights if they dim. That could most likely be a weak battery, because the lights should still be bright even if the alt wasn't charging at all.

But yes, go diagnose and fix the vac leak, then tell us how the charging situation is.

[donovandishon]

we have a new battery and altenator tested out fine....service engine light cam on and gave us the code for the cam position sensor.....does anyone know if this could cause this

[freeze12]

Yes...A bad cam position sensor will cause the idle to fluctuate.A bad Throttle Position Sensor will also do that.Not a bad idea to clean the Idle Air Control Valve with some Throttle Body Cleaner also.

[clutch1]

Interesting, I was really hopin for the "bank X too lean" code, lol! Probably not a vacuum leak then

Get on the signal wire for the cam sensor with an Oscope (find a mechanic buddy) and see if you get 1 12v digital spike every 2 turns of the engine to see if the cam sensor is working right. Also check for 12v and ground on the other 2 wires.

Got the actual code, also? That may help, could be correlation, which could be bad like a timing chain jumped tooth, or just cam sensor circuit, which would be most likely the sensor, or of course a bad wire somewhere.

[donovandishon]

ok i got three codes for the O2 sensor can this be the cause of my idling problems

[lord2heart]

pretty sure the system would go to open loop if the sensor is bad. so, no? but you should get that replaced

[zzyzzx]

If you are getting codes and have a problem, fix the codes first.