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Discussion Starter #1
Occasionally, on a clear, bright day, the headlights on my '98 Seville will be on and the result is a hard to read instrument cluster. Even with the dimmer turned to the brightest setting (fully clockwise), it's nearly impossible to read the gauges. If I turn the twilight sentinal off, the message center will read "Headlamps Suggested"!

In the past, I had other vehicles (including two Cadillacs) with the automatic headlamp feature, and the cluster was always readable even if the lamps were on during a cloudy day, etc. However; today it was not cloudy, and the headlamps were on!

I have the Cadillac service manuals (3) for this car, and although I have not read them from cover-to-cover, there doesn't seem to be anything relating to this problem (if it is a problem).

A friend suggested maybe the sensor was dirty, so I tried to clean it with a cotton swab; but, to no avail. Any suggestions other than to just not use the twilight sentinal feature?
 

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Does your car have "rainsense" wipers?
You know, if the water splashes on the glass there is a big sensor by the mirror that tells the computer to clean the glass.
On cars with rainsense if the switch is left in delay mode the wipers won't move unless there is water on the glass.
BUT, part of this means that your headlamps are commanded "On" so if you have them manually turned off and rainsense is active, but it's not raining, the headlamp message will be displayed just like you describe.

Turn the wiper switch off and recheck it, I bet it will go away.
I have seen lots of folks get burned by this simple oversight.

HTH
 

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ewill3rd said:
Does your car have "rainsense" wipers?
You know, if the water splashes on the glass there is a big sensor by the mirror that tells the computer to clean the glass.
On cars with rainsense if the switch is left in delay mode the wipers won't move unless there is water on the glass.
BUT, part of this means that your headlamps are commanded "On" so if you have them manually turned off and rainsense is active, but it's not raining, the headlamp message will be displayed just like you describe.
Turn the wiper switch off and recheck it, I bet it will go away.
I have seen lots of folks get burned by this simple oversight.
HTH
Excellent advice.... No, make that outstanding advice!!!!

Been there, done that one.
 

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i agree the rainsense messed up on my 98 sts had the headlights suggested even with the switch in the off pos.
 

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Discussion Starter #5
Thanks for the suggestion. I do have "Rainsense" wipers; but, if I remember correctly, on the day in question it was not raining and the wipers were "off". So, is there some "secret" connection between rainsense and twilite sentinal?

As I said in the original thread, it was a clear, bright day and the headlights were on. If I deliberately deactivate the twilite sentinal, I can read the instruments; however, now the message "Headlamps Suggested" appears in the DIC. When the headlamps are on in bright daylight, the instrument cluster is nearly unreadable because it is dimmed and with the bright sunlight glaring in the car, it is just about impossible to read.

I'm still puzzled.:hmm:
 

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ewill3rd said:
On cars with rainsense if the switch is left in delay mode the wipers won't move unless there is water on the glass.
HTH
So that's why my wipers weren't working! :) I was getting ready to post a message asking if anyone knew possibly why they weren't working! :)

--- Goobz!
 

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Well buzz, it is possible that you have a bad rainsense module. I have only replaced 2 in my career but it is mathematically possible.
Honestly some diagnosis should be done when it's acting up.

The reason it becomes such a strange problem is that if rainsense is active, yes, it automatically turns the headlights on. Some states have adopted a law that states something to the effect that if your wipers are on your lights must be also. So GM set it up that way. If you are positive that the wiper switch is fully in the off position then you may have another problem but I'd recommend that you let someone put their hands on the car. I am not sure how much more help I can give you over the internet.
 

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Discussion Starter #9
Here's the latest on this frustrating situation:

Today, it was very hazy with light rain. When I left the house, the headlamps were not on, although the Twilite Sentinel feature was activated as it usually is. When it started to rain/mist, I turned on the Rainsense wipers to the slowest setting and the wipers began operating in the normal automatic wiper fashion.

When I looked at the dash, in the lower left corner it indicated the headlamps were on; however, the dash was fully illuminated as it would be during daylight hours with the headlamps off. In other words, the dash was fully readable and everything seemed to be working correctly even with the Rainsense wipers activated.

As I mentioned in the previous thread, on a clear, bright day, the headlamps will occasionally be on as if it was dark outside. When this happens, I am forced to either turn off the Twilite Sentinel (and see the message "headlamps suggested" in the DIC) or adjust the dash dimmer button to the highest setting so the instruments are somewhat legible.

One of the suggestions had to do with a connection between the Rainsense wipers and the Twilite Sentinel; however, as was proven today, if it is daylight and the wipers are activated, the headlamps are turned on; but, the dash is not dimmed as it would be at night. My next step will be to dig out the '98 Seville service manuals I purchased a few years ago, and start digging for a possible answer. This problem only started occuring within the past 2 years. I don't remember ever having the problem before, so something is wrong. Possibly one of the sensors on the top of the dash is acting up?:hmm:
 

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The dash lights should be bright during daylight hours with the lights on. That is called "parade mode". Check your owners manual. Does your car have fog lights? They may be on. If they are, then it turns on the headlights as well. Atleast that is how my '02 works. If the fog lights are not the culprit, then I would lean towards one of the sensors.
 

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Discussion Starter #11
Thanks, Ranger:
Yeah, the dash lights should be bright during daylight hours, even with the headlamps on; however, on occasion, the dash is dimmed and the only way to read the instruments is to turn the dimmer to full bright, or turn the headlamps off by setting the twilight sentinel to off.

Interesting to note; although I have tried to clean the sensor with no success, last week, after having the car professionally cleaned, the lamps seem to be working correctly in full daylight with the wipers activated.:cool2:

Maybe, these guys found the "piece of dirt" that was partially masking the sensor and cleaned it? So far, "knock on wood", everything seems back to normal... I'll stay in touch on this.:worship:
 

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Here's the deal with the fogs and the Rainsense(TM) wipers:

First, the daylight sensor operates independently of the Rainsense system. If you turn on the Rainsense wipers and the daylight sensor thinks its daylight out, the headlights will come on but without dimming the instrument cluster. It's smart enough to know that despite the fact that the BCM has called for headlights that it's still light outside and will thus leave the instrument cluster bright. Only when the sensor thinks it's dark out will the instrument cluster dim.

Second is the fogs. The foglight switch only turns on the fogs, parking and tail lights. When in gear, the DRLs turn on giving the appearance that the headlights are on. If you put the car in park, DRLs go out and you're left with fogs, parking and tail lights. If your headlights stay on in park it's because the daylight sensor thinks it's dark out. When you turn your fogs on during daylight hours the car is still smart enough not to dim the instrument panel (or turn the headlights on) even though you have the LIGHTS ON lit up.

So bottom line is that your car thinks it's dark out when it is not really dark out. The only way to tell for sure is if the instrument cluster is dimming. Headlights and foglights can come on independent of the dimming-of-the-instrument-cluster. It's either the cover on the photoelectric sensor has gone foggy or the sensor itself. If you're getting a HEADLAMPS SUGGESTED MESSAGE during the day it's a pretty clear indication that the sensor is bad (or has fallen down into the bowels of the dash - BTDT).

Jim
 

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Discussion Starter #13
I'm about ready to throw in the towel on this one!:(

Yesterday morning, on a clear & bright day, once again the headlamps were on and the dash was dimmed! It was NOT raining or snowing at the time, and the wipers were OFF!

As I mentioned earlier, I thought maybe I found the cure after a professional car wash detailing; but, to no avail. When it warms up next spring, I will, get the manuals out and maybe track down the cause of this frustrating problem.
 

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My wife's 2002 STS has been having the same problem: nice bright sunny day outside and the words "LIGHTS ON" appear on the left side of the dash. When you slide the twilight sentinal all the way to the left, the lights go off, but the "HEADLIGHTS SUGGESTED" message appears in the middle. She took it to the dealer today as it's still under warranty and they say this is "normal". B.S.
No way should the lights be lit on a sunny day, nor should the 'headlights suggested" message appear. The first couple times this happened, I cleaned the light sensor with a Qtip and alcohol, and the lights worked normally. I even did the following checks, as it hard to tell in the daylight whether the DRLs - Daytime Running Lights(reduced output) are on or whether it's the low beams.
1. Engine on, transmisssion in DRIVE, twilight slider all the way to the left, "headlights suggested" on DIC, the low beam lights are on, but appear to be the DRL's (Daytime Running Lights). Put transmission in park, and the front lights go off. I believe this is one on GM's features for DRLs: they go off when the transmission is put into park.

2. Engine on, transmission in DRIVE, twilight slider in middle, "lights on" message is up. Move the turn signal stalk forward or back (can't remember which way) and the high beam indicator comes on. Slide the twilight slider all the way left, the "lights on" indicator goes out, the "headlights suggested" message comes up, the low beams are on(DRLs), but when I try to activate the high beams, no H.B. indicator shows. This means the headlights are not on, only the DRLs. Agree?

Now, am I right about what the proper functioning of the DRLs and headlights should be? If I am, how do I convince the service writer that the car is not working correctly?:cookoo:
 

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2blue said:
My wife's 2002 STS has been having the same problem: nice bright sunny day outside and the words "LIGHTS ON" appear on the left side of the dash. When you slide the twilight sentinal all the way to the left, the lights go off, but the "HEADLIGHTS SUGGESTED" message appears in the middle. She took it to the dealer today as it's still under warranty and they say this is "normal". B.S.
No way should the lights be lit on a sunny day, nor should the 'headlights suggested" message appear. The first couple times this happened, I cleaned the light sensor with a Qtip and alcohol, and the lights worked normally. I even did the following checks, as it hard to tell in the daylight whether the DRLs - Daytime Running Lights(reduced output) are on or whether it's the low beams.
1. Engine on, transmisssion in DRIVE, twilight slider all the way to the left, "headlights suggested" on DIC, the low beam lights are on, but appear to be the DRL's (Daytime Running Lights). Put transmission in park, and the front lights go off. I believe this is one on GM's features for DRLs: they go off when the transmission is put into park.

2. Engine on, transmission in DRIVE, twilight slider in middle, "lights on" message is up. Move the turn signal stalk forward or back (can't remember which way) and the high beam indicator comes on. Slide the twilight slider all the way left, the "lights on" indicator goes out, the "headlights suggested" message comes up, the low beams are on(DRLs), but when I try to activate the high beams, no H.B. indicator shows. This means the headlights are not on, only the DRLs. Agree?

Now, am I right about what the proper functioning of the DRLs and headlights should be? If I am, how do I convince the service writer that the car is not working correctly?:cookoo:
The dealer is full of crap. If it says "HEADLAMPS SUGGESTED" in day light (and your wipers are not on) then the car thinks it's dark out for some reason. It's broken. The DRLs are a reduced version of the low-beams and will only come on when the car is in gear and when the headlights are not being called for. You are correct in that the high-beam indicator will not come on with the DRLs on (unless you use the 'flash to pass' feature). The only time the LIGHTS ON indicator should be lit during the day is if you've manually turned on the parking or headlights OR you have the wipers on.

Jim
 

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One correction here. Unless I am mistaken I believe the DRL's are reduced power to the high beams, not the low beams. That said, TurboJimmy is correct. I think you have a bad sensor.
 

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Discussion Starter #17
Well apparantly, I'm not the only one with a problem here::(

In any case, although cleaning the sensor(s) doesn't seem to help, the next step will be to have it(them?) replaced. By the way, on the top of the dash, there appears to be two (2) sensors, one on the driver's side and one on the pass side. Are both of these involved with the autolamps?
 

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I'm not sure about a '98, but on my '01 the DRLs are the low-beams. Normally I wouldn't notice such things, but I have SilverStars in the low beams and they look a lot different than the high beams.

Again, not being sure about a '98 I don't know which of the 2 sensors would need replaced. I think at that point in time one was the daylight sensor and the other was the sunload sensor. On my '01 they're combined into one sensor in the center of the dash. I don't know for sure, though. Maybe someone with more knowledge on the '98 can chime in.

Jim
 

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Sounds like you guys might have some bad ambient light sensors.
Make sure they are not covered up with anything. Should be right in the middle of the defroster grille.
Anybody worked on them lately? Maybe someone left the sensor unplugged?
 

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buzz said:
Well apparantly, I'm not the only one with a problem here::(

In any case, although cleaning the sensor(s) doesn't seem to help, the next step will be to have it(them?) replaced. By the way, on the top of the dash, there appears to be two (2) sensors, one on the driver's side and one on the pass side. Are both of these involved with the autolamps?
There are 2 "sunload" sensors on my '02 (not sure about your car). They are dome shaped and are for the A/C system. The ambient photo sensor is flat topped and recessed just a bit. That is the culprit.
 
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