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What light's ? Headlamps ?
The lamp control module (LCM) monitors the ambient light conditions through the ambient light sensor. The ambient light sensor is a variable resistor whose resistance changes as the surrounding ambient light level changes. As the ambient light decreases, the resistance of the ambient light sensor increases. The LCM measures the resistance across the ambient light sensor and determines whether it is day or night.
Does the vehicle have DRL - daytime running lamps - Twilight Sentinel ?????
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 to have had some FUN with this darn system and replaced ignition cylnder(dealer has to program)can help usally for a few years ....but i dont want to swaer thats the samething causeing yours......feel free to repost
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.
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.
Left of the two headlight buttons for headlights and parking, there is a vertical slider. It's labeled Twilight, meaning twilight sentinel that keeps the headlights on. Move it down and that shortens the on time to about 5 seconds. If you are sittting with the headlights on and want them to go off, push it to the bottom and it turns the lights off immediately. They will turn back on when the car is put into park.
Move the slider to the top and they should stay on for about 5 minutes. BTW if you just leave the headlight switch pushed in (if you're doing it manually) the car turns everything off in about 10 minutes--inside lights, radio, lights, cigarette lighter power (unless you moved the fuse in the underhood fuse block to make them stay on permanently).
You also may not know that if you are driving or sitting and want the headlights off but the parking lights to stay on, push the Parking LIghts button. That turns the headlights off. I didn't find that for a while because our 98 LeSabre didn't have any way to turn off the headlights while cruising through a Christmas display scene in a park where many people turn off the headlights to help the effect of the colored lights. Please Rate My Response! Thanks!
sounds like there is a short somewhere. you need to start checking things with a multi meter, could be a bad switch. I would recommend picking up a factory service manual for your vehicle off of ebay. If you need any further assistance let me know. Thanks, lee
Check your fuses first. In a '92 Roadmaster, they would be number 14 and 15, light blue 15A fuses. I am not sure about other years, but your owners manual should tell you. Otherwise it could be the headlight switch, or the Twilight Sentinel Module if your car has the option. I had a similar problem a few months ago with my '92 Roadmaster Wagon. My problem was due to the Twilight Sentinel Module. If your parking lights do not come on (dash lights, too), but the headlights do when your Twilight Sentinel should turn them all on, try to use the rocker switch to turn on the lights. If the parking lights come on with the rocker switch, I believe you need a Twilight Sentinel Module. However, if you do not have a Twilight Sentinel Module, or your lights do not come on using the rocker switch, you may have a bad switch or faulty wiring. The Twilight Sentinel Module is located way up under the dash, to the right (passenger) side of the steering column where the column goes through the firewall. It looks like the one in the picture, and could be off white or gray, or perhaps a different color.