Taillights - autoactivate

[JLU6]

2004 Deville;

Taillights don't come on with headlights when auto activated at night time. They do come on when switch is used to turn on head and taillights.

Anyone have any thoughts?

Thanks,

JLU6

[CoupeDTS]

Thats the way my 2000 was. Ive seen other 2000+ devilles driving around and you can see the headlights are at 50%(?) power and no taillights which means they didnt turn the headlights on. My 96 fleetwood on the other hand I never have to hit the headlight switch because the headlights and tails will come on once in gear like you are wanting. I think alot of GMs are different from different years and models. I like my wifes 05 Buick Rainier where everything will come on automatically but you can also turn the switch to turn the headlights off while sitting and idling which you cant do with other GMs.

[Cadillac Jim]

I think that if the taillights don't come on when the twilight sensor detects sundown and turns on the headlights, you have a malfunction. You can do a quick check of the fuses and bulbs with the dashboard switch, just pull it out and push the deal slider all the way to the left and across the detent.

Check the running lights too.