This Caddy's "twilight sentinel" is causing the lights to go out.

Dear Car Talk

Dear Car Talk | Feb 01, 1998

Dear Tom and Ray:

We own a 1989 Cadillac Seville. The car is equipped with a "twilight sentinel"
system, which automatically turns the headlights on and off. Our problem is that
our headlights go out while driving at night. We had been operating the
headlights manually, but, without warning, they would go out. We are now
operating the lights only under the sentinel system, which has a 180-second
delay before the lights go out. And sometimes the driver information center
intermittently flashes the 180-second delay and runs up and down through the

Our local Cadillac dealer has had the car twice and can't seem to locate the
problem. They say the only thing they can do is start replacing parts one at a
time until they fix it. -- Al

TOM: Well, I'd be suspicious if they say they want to start with the
transmission or the trunk lid, Al. But if they're willing to start with the
sentinel unit, I'd let 'em have a shot at it.

RAY: On cars without a twilight sentinel, this sort of problem is usually caused
by a bad headlight switch. But in this car, I believe the headlight switch and
the sentinel are all part of one unit, so you're going to have to replace the
whole thing.

TOM: It'll probably cost you about 150 bucks, Al, but I'd be willing to bet that
solves your problem.

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