04 Deville Headlights dimming.
 

Hi All.
I was wondering if anyone else has heard of the issue I am having.
I bought an 04 Deville with 31k to replace my 00 with183k on it.
The car is perfect except for an annoying quirk. When I drive at night and use either the twilight system or the main headlight switch after about 3 minutes everything electrical,Headlights, Dashlights, I assume Taillights too ) in the car dims for about a second. Also the blower slows down. And then it will be fine from then on. Is this a quirk of this model year? Any idea's would be welcome. Thanks

My 2000 Deville does the same thing. I've owned several vehicles and often if you are driving and then decide to come to a stop, the engine speed drops quickly, and often at low rpm the alternator isn't sending as strong of a current so the draw is then placed on the battery, which has a lower voltage rating than the current sent from the alternator, that would cause a flux in the most electronics, but you would only notice that change in the headlights. I understand your frurstration but there's not much you can do.

You could check your voltage rating when the car is running just to be sure you have a strong alternator, it should be between 13-14.5 volts.

It sounds normal to me. There are alot of electonic devices that operate on these cars, more than the average car so it uses more power.

Thanks for the input. This happens at any speed. I can be doing 25 or 70 or at idle for that matter and it does the same thing. I turn on the lights and about 3 mins later everthing flickers one time. The voltage out put is fine . BTW I am a good mechanic I rebuild old 60's mopars in my spare time. and did all the normal checks loose wires, grounds, regulator etc. Its just a mystery.

is it possible it's the cooling fans or air conditioning? it definitely sounds like something is turning on, creating a draw somewhere?

Could be something like that. I was thinking since it only happens once everytime I start it and drive off, that it might be the air suspension compressor coming on and setting the ride height. I am going to disconnect it and see if it stops doing it. Thanks for the input. I'll let you know what happens.

Found the problem
 

Hi all,
It was the air compressor. Mystery solved. Shut it down and the problem goes away.
Also, I talked to the original owner I bought the car from and he said it always had the problem from day one. The dealer could never figure it out after 4 tries. The owner said he just stopped trying to get it fixed because it was just a quirk that he got used to.

Thanks.

do you mean the AC compressor?

if that is what you mean, someone should test the electrical LOAD when the AC clutch is activated.

wondering .. does it do it if it is set to economy and turn the dash fans on? another possible item for electrical overload.

how old is the BATTERY?
is the battery of the proper size?
are the battery connections PERFECTLY clean and coated ?

as musique stated, the alternator should put out the rated voltage at any speed, from 700 rpm to 5,000 rpm, w/o any significant variation. there again, you may also have CONNECTOR problems ..

ADVICE: read our e-ghosts thread, FAQ sections.










.

My 05 does the same thing. It's noticable sometimes more than others. Is this the AC compressor or air ride compressor? Thanks, K

Air Ride
 

Its the Air Ride Compressor. That explains why it only happens once after start up. Its not a problem for me, just peaked my curiosity on why it was doing it. Other than that, its perfect. Love the big Caddy's.
Thanks