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97 deville The ''day'' headlights work, but when I pull out the ''lights on'' knob, or turn on the ''twilight'' switch, the day lights go out, and the regular head lights won't come on. The brake lights and tail lights work fine.
I had the same problem - it was the headlight relay switch (located under the plastic cover that houses the fuses under the hood). Remove the cover and you'll find the relays. They are normally wrapped in electical tape - you'll have to peel off th etape to get to the right one. You can identify the correct one from your owners handbook. Try (temporarily) using the accessories relay located right above the lights one.I had the same problem - it was the headlight relay switch (located under the plastic cover that houses the fuses under the hood). Remove the cover and you'll find the relays. They are normally wrapped in electical tape - you'll have to peel off th etape to get to the right one.
You can identify the correct one from your owners handbook.
Try (temporarily) using the accessories relay located right above the lights one.
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Re: 97 deville The ''day'' headlights work, but when I...
It is typical for daylights to go off when headlights are turned on. So check each headlight bulb cause it could be as simple as that. If they are OK then the switch has to be checked & power to the bulbs
Re: 97 deville The ''day'' headlights work, but when I...
Had a similar problem on a american car like this and i had to order then fit a complete new switch assembly,firstly as an import it was expensive and i had to travel to murcia half hour drive away to order part from only an authorised GM dealer although i have one local they couldnt order part.
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Twilight feature is used by the BCM to turn on the headlights when light levels diminish. Dash, cluster lighting is controlled by a rheostat near the headlight switch. The rheostat is rolled up for brighter lights. If this does not work the interior module may have burned out or the rheostat may be bad. If interior lights come on when rheostat is rolled fully up it most likely is OK. Interior lighting module is located above the headlight switch beside the cluster on the left side.
Examine the left dash panel to find the headlight switch. This is the control you use to turn the headlights on or off, with the exception of the daytime-running lights.
Look directly beneath the headlight switch. You'll see a small lever. This is called the "Twilight Sentinel." Move the lever all the way to the left to the "Off" position.
Turn the headlight switch to the "Parking Lights" mode. This icon has a symbol of two small bulbs. The daytime-running lights are now turned off.
It's probably the lighting control module , but without doing some electrical testing that is just a guess !
Battery positive voltage (B+) is applied at all times to the lamp control module (LCM) through the underhood junction block HDLP MaxiFuse® and CKT 1242 (RED).
When you place the headlamp switch in the HEAD position, the headlamps input to the LCM is grounded. The LCM then applies battery positive voltage (B+) through the underhood junction block HDLOBML fuse and HDLOBMR fuse, which feed the left low beam headlamp and the right low beam headlamp respectively. When you activate the headlamp dimmer switch by pulling on the multifunction lever until the switch clicks, CKT 524 (PPL) is grounded to the LCM. The LCM then removes battery positive voltage (B+) from the low beam headlamps and supplies battery positive voltage (B+) through the underhood junction block HDHIBML fuse and HDHIBMR fuse, which feed the left high beam headlamp and the right high beam headlamp respectively.
Twilight Sentinel Circuit Description
Twilight sentinel determines whether the daytime running lamps (DRL), or the exterior lamps and the low beam headlamps at full intensity should be on based upon the signal of the ambient light sensor. When the ambient light sensor detects daytime, the twilight sentinel turns on the DRL. When the ambient light sensor detects darkness, the twilight sentinel turns on the exterior lamps and the low beam headlamps at full intensity. The twilight sentinel also keeps the lamps on for a delay period of 3 to 180 seconds under the following conditions:
• The vehicle is in PARK.
• The ambient light sensor detects darkness.
• The ignition switch is turned to the OFF position.
You may turn off the twilight sentinel manually. When it is dark and the gear selector is in PARK, pushing the twilight sentinel switch to OFF will turn off the headlamps and exterior lamps. Pushing the twilight sentinel switch to OFF again will turn on the headlamps and the exterior lamps. If the gear selector is not in PARK, pushing the twilight sentinel switch will have no effect.
The F- switch is just an input from the LCM - lamp control module .
Do you know how to test control module inputs an outputs ? Very easy to fry a module if you don't know how to do it .
Also have a full scan of all modules on the vehicle , could have DTC'S - diagnostic trouble codes stored . Not for the OBD 2 engine computer . The instrument cluster , BCM , LCM can all set codes too, related to lighting an someother thing's . ECM Inputs and Outputs Diagnosis
You can find free wiring diagrams here http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model and engine ! Under system click on lighting ,then under subsystem click headlamps . Click the search button then the blue link . The first diagram you will see at the top the power supply to the LCM , down a little you will see the headlamp switch , ambient light sensor . Now if you want to start replacing thing's without testing good luck !
I can't see the switch causing the rear lights to fail without affecting the headlights also. Is it possible that the only headlights you got to work at the time are the daylight headlights - for visibility during the daytime? the breaklights work so you've not got faulty lights. Also the fact that both left and right brake lights work points to the switch as being the culprit. Is it possible that when you reinstalled the knob it's just not placed on there correctly? That would prevent the switch from possibly operating correctly. Check your turn signals. If they both work that should instill confidence that the switch is the culprit. If you're brave (I don't know your level of "handymanness") you could pull the switch knob off again and this time look very closely at the knob and the post it slides onto. Most knobs (I believe yours should twist, not pull, but I'm not sure as you don't list the model) press onto a post that is "D" shaped. The knob has a corresponding recessed hole that is also shaped like a "D" Assuming (yeah, it makes an xss out of you and me...) that you placed the knob correctly the first time is it possible that the dash cutout is limiting the switch movement? This would only occur if the knob wasn't placed correctly. I'm not sure again because you don't list the model. If all else fails then replace the switch - available at most all auto parts stores. Good luck!
I have a 1997 cadillac deville that has both 'daytime running lamps' when put into gear and 'twilight sentinel' which turns the headlamps and parking lamps on at night, and goes off during the day or when it is bright enough.
There is an adjustable delay for the twilight sentinel to turn the headlights off after the ignition key is removed and it is night time.
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I had the 'daytime running lamps' installed on a 1990 Cadillac Deville that turns the headlamps only on when the ignition key is switched to on with an aftermarket module. The headlamps are about 70% or so as bright as the regular twiilight sentinel headlamps and parking lights and are designed to go on during the day.
The twilight sentinel overrides this feature when it gets dark outside.
I had the daytime running lamps installed by an auto electric shop that specializes in electrical systems, alarms, stereos, etc.
buy a test light ground test light turn key on and check all fuses touch the top of each side ofer ever fuse ,if only one side of fuse light up then it is blown,,,,could be inhead light switch
Under the light switch knob, there is a sliding switch. Moving it to off will make the lights turn off as soon as you push the knob in. Anywhere else the slider is set will make the lights stay on for a variable period of time, depending on where the switch is set. I leave mine just to the right of off. That way, the headlights turn on and off automatically. You don't pull the knob out in this position....check your owner's manual for the twilight feature.
I had the same problem - it was the headlight relay switch (located under the plastic cover that houses the fuses under the hood). Remove the cover and you'll find the relays. They are normally wrapped in electical tape - you'll have to peel off th etape to get to the right one.
You can identify the correct one from your owners handbook.
Try (temporarily) using the accessories relay located right above the lights one.
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