Headlight Sensor 1999 PA Base Model

[bigsky]

I have a problem with the headlight sensing system. During the day the headlights and other lights are on (just as if it were night)...and it is intermittent (hate to use that word). Sometimes it all works fine. Anyone have a similar problem they traced to a switch/relay/sensor? This post is a bit of a follow up to a question I had about the HUD. When all the lights are on during the day the HUD dims and cannot be seen.

[imidazol97]

Originally Posted by bigsky

I have a problem with the headlight sensing system. During the day the headlights and other lights are on (just as if it were night)...and it is intermittent (hate to use that word). Sometimes it all works fine. Anyone have a similar problem they traced to a switch/relay/sensor? This post is a bit of a follow up to a question I had about the HUD. When all the lights are on during the day the HUD dims and cannot be seen.

This sounds like my problem with 2003 LeSabre. Sometimes the headlights stayed on and I didn't want them on. Other times they were off. Dealer looked at it twice. The second time his tech realized that when he wipers are on that means it is raining and in most states if it's raining the headlights have to be on. So the wipers being set to the auto-sensing position turns the headlights on.

I had noticed it when I turned the parking lights on while traveling so that the rear taillights were on for safety. The switch was warm and I noticed the little indicator light was on meaning the headlights were on.

Does your PA have rain-sensing wipers?

[bigsky]

imidazol97 - Looks like we frequent the same boards. That is good to know, that the wiper sensor may be involved with this. This car has the moisture sensor, and a short in the switch could be the problem (the wipers were not on when the problem occurred). I will continue to investigate. Maybe others have had a similar problem? Would be good to fix this...when the lights are on during the day I cannot see the HUD as it goes into a reduced brightness mode.

[TopherS]

I had a nearly similar issue with my 01 PA. I have the HUD and rain-sensing wipers, but my headlights don't go on with the wipers at all...no connection on mine.

What was happening with mine is that if it wasn't high noon outside, my lights were on (making the HUD dim). I noticed almost every other GM car/truck w/ auto headlights were driving still with their DRL's only, so I knew it was just my car. What I did was replace my sensor (in the center of the dash). Turns out, it is very easy, but be careful. I went to a salvage yard and found similar sensors on other cars (IIRC, they were early 90's Cadillacs). The sensor will come straight out of the base if you ***very carefully*** use a flat-tip screwdriver to lift up on the round black/blue shield of the sensor (ease up from different locations so as to not break the shield off)...you don't have to remove anything else. The sensor uses a base similar to a 194 light bulb, so if you pull straight out, it will come out. I say practice on the salvage yard cars first...to get the feel.

I got a couple from the salvage yard (they did not even charge me for them...don't think they really knew what they were). It seems the sensors vary in how much light trips them, as I found one that did not turn on my lights until it was much darker than I was comfortable with. The 2nd one I tried seems perfect. The lights come on at a point that I feel comfortable with (any lighter outside...headlights/running lights not necessary, HUD too dim; any darker...feels too dark to be driving w/o the running lights).

I've had no problems with the lights since. Seems to be working famously.

Hope this helps.

[bigsky]

TopherS...Thanks...Good information. I checked on mine and the headlights and wipers also do not have this connection (like the Lesabre's apparently do). I have been thinking to start with the sensor or loose connections, or even the LCM (lamp control module). I think I could very easily have this same issue. A good lead...thanks again.