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2001 Eldo ETC, 1956 CDV, 1958 Biarritz
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Discussion Starter #1
2001 Eldo ETC Interior lights not coming on when you open the door, but they come on manually when you turn the headlight knob.

Don't know if this could be related, but the headlights don't come automatically on at night. Have moved the Twilight Sensor slide, but no effect.
 

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98 DeVille, 97 DeVille d'Elegance
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Re: 2001 Eldo ETC Interior lights not coming on when you open the door.

If the twilight sensor is bad it will not turn interior lights on since it thinks it's daytime and would explain the tw headlight not working also.
 

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2001 Eldo ETC, 1956 CDV, 1958 Biarritz
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65 Posts
Discussion Starter #3
Re: 2001 Eldo ETC Interior lights not coming on when you open the door.

If the twilight sensor is bad it will not turn interior lights on since it thinks it's daytime and would explain the tw headlight not working also.
Interesting that the interior lights don't come on in the daytime. Never realized this before.

Is the Twilight sensor the half round piece in front/center of the dash, or the inset sensor? I think that the half round is the sunload sensor that has something to do with the AC.

If I understand you, I should replace one or both of these? Thanks for your help.
 

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98 DeVille, 97 DeVille d'Elegance
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TW sensor is flat round sensor, the round flat one is for sun load for ac. Not sure if it's bad but someplace to start.... try cleaning the sensor, to test put something over it for a few minutes and try the lights again(open door). It very well could be something else(not sure what module controls input from the sensor for your year)
 

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2001 Eldo ETC, 1956 CDV, 1958 Biarritz
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Discussion Starter #5
TW sensor is flat round sensor, the round flat one is for sun load for ac. Not sure if it's bad but someplace to start.... try cleaning the sensor, to test put something over it for a few minutes and try the lights again(open door). It very well could be something else(not sure what module controls input from the sensor for your year)
Is there a way to test the TW sensor? I tried cleaning it. No difference. I tried covering it and car still thinks it is daytime. I would guess that it is a normally open or normally closed cicruit, so I could short the sensor wires together or cut one of them to test it?
 

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98 DeVille, 97 DeVille d'Elegance
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I don't have a FSM for your year so can't tell you diag process for it specifically or the wire colors and sizes, if it's normal open or closed, but it is a resistor circuit. Jumping is a possibility for sure, use a fused jumper wire if you do it. The diag process also has checking the headlight switch for faults.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,250 Posts
along with the interior lights NOT turning on -

does the chime work
if you leave the keys in the ignition - engine off - and open the door -

does the chime work
if you manually have the headlights on - key off - and open the door -
 

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2003 Seville STS
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140 Posts
I had exactly the same problem when I bought my 2003 STS. Found a replacement sensor in a junkyard, and that fixed it. The counter girl didn't even charge me for the sensor!

Jamie
 

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2001 Eldo ETC, 1956 CDV, 1958 Biarritz
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Discussion Starter #9
I cut the wires going to the sensor. Now the car thinks it is always night time and everything works! I outsmarted the damn thing!

So, apparently, the sensor is a normally closed switch when it detects light.

I have another sensor from a junk yard and will wire that up. I am getting a code that says "sensor not working" or something like that.

It did and still does chime if I manually turn on the lights, shut the engine down and walk away. Also if I left/leave the ignition key in.
 
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