Ok people, I have officially fully installed Twilight Sentinel (automatic headlights) and Daytime Running Lights on a 1989 Oldsmobile Cutlass Supreme, a 1992 Buick Regal, and a 1994 Cutlass Supreme successfully and it wasn't as hard as I thought it would be. Here's the write up with first of all, a few notes:
1. You can find the required modules for this procedure in American W-body vehicles manufactured from 1995-1998.
2. This was an optional package for anyone that requested Daytime Running Lights, or DRLs, with their vehicle at that time and was not included as standard equipment.
3. DRLs or the DRL module is not required of you only want Twilight Sentinel headlights to work. Just be advised that the automatic auto-lamp control module will have a live wire on it intended for DRLs.
4. The automatic lamp control module is usually a black (most W-body vehicles) or white (Lumina/Monte Carlo) rectangle box located to the left of the steering column inside the dash board and usually with the BCM hanging next to it and is the module with the 2 plugs in it furthest toward the firewall. The DRL diode module is the dark purple/burgandy or black module that is a rectangular heat sink with just a 2 pin plug in it located on the same side more toward the front of the dashboard. The sensor is located under a small hole in the top of the dashboard toward the windshield on the drivers side.
5. Depending on your W-body vehicle, there are a few things that you can wire to your preference.
6. If you are installing DRL as well, you will be using all wires on the headlamp control module. There should not be any wires left loose.
7. You will need wire splice connectors because this will not require your to cut any of your normal headlight switch wires if done properly. This is only an add-on module.
8. Some headlamp switches are not wired with 2 separate plugs, but, rather a single plug with thick wires on one side and thin wires on the other. Just substitute the thick wired side for the "Large Plug," and the thin wired side for the "Small Plug."
Wires you will need to know and their designation:
On the headlamp switch:
1. Dark Green (Headlight power input. Hot at all times).
2. Orange (Parking and dash light power input. Hot at all times).
3. Yellow (Switched power output to headlamps).
4. Brown (Switched power output to parking lamps and dash).
5. Yellow/Black (Used for flash-to-pass if so equipped. Hot when headlamp switch is off).
6. Black (Ground).
1. Pink/Black (Hot in run, bulb test, or start).
2. Grey (Dash lamp dimmer).
On the automatic lamp control module:
1. Dark Green (Headlamp power input).
2. Light Blue (Parking and dash light power input).
3. Yellow (Headlamp power output).
4. Brown (Parking lamps and dash power output).
5. Dark Blue (Daytime Running Lights power output).
1. Brown (Headlamp/DRL signal power on. Hot in run).
2. Pink/Black (Parking and dash light signal power on. Hot in run, bulb test, or start).
3. Light Green/Black (Ambient light sensor positive).
4. Yellow/black (Ambient light sensor ground).
5. Light Blue (Parking brake signal).
6. Tan/White (Parking brake warning light).
7. Black (System ground).
On DRL module:
Two pin plug;
1. Dark Blue (Lamp power input).
2. Tan (Lamp lowered power output).
Here are the installation steps:
Step 1: Install the ambient light sensor since this might be the most intrusive part of the procedure. Now, if you've had to cut it out of another vehicle, like I had to, you may want to add more wire to it.
A. Some GM vehicles already have a hole designated for this sensor in the top dash pad usually in the driver's side speaker grill. If you removed the sensor from the donor vehicle properly, all you should have to do is remove the top dash pad, and twist and lock the sensor into it's designated socket in the dash pad hole just like you would a twist and lock vehicle lamp holder. Next, run your wire through the dash to the location where you will be placing your headlight control module.
B. If you do not have this hole or socket, or are unable to find it in your dash pad, install the sensor into the secondary black plastic defroster grill. It will fit snugly in between 2 of the middle grill vents. With this, you can adjust the sensor either higher or lower in the grill according to how much light you want it to react to. Next, run your wire through the dash to the location where you will be placing your headlight control module.
Step 2: Remove your headlamp switch from the dash (if you have not already) and proceed to start wiring the small plug from the auto-lamp control module.
A. Connect the ambient light sensor to the plug and make sure that the light green/black and yellow/black wires are connected properly.
B. Connect the brown headlamp control wire. This wire should be connected to an output that is only hot in run and not start or bulb test mode. Connecting it this way will prevent the headlights from being lit during ignition.
C. Connect the pink/black parking lamp control wire. This wire may be connected according to your preference. If you wish the parking and dash lamps not to be lit during ignition, then you may connect this wire to the same as the headlamp control wire. If you do not mind the parking and dash lights being lit during ignition, you may connect this wire to the pink/black wire on the headlight switch via splice connector.
D. Connect the light blue parking brake control wire by first disconnecting the clip on connector from the parking brake, then, cut the clip on connector off with some wire on it. Strip that wire and then connect it together with the light blue wire attached to the small headlamp control module plug.
E. Connect the tan/white parking brake warning wire to the tan/white wire that you just cut from the parking brake clip on connector.
F. Connect the black ground wire to the black ground wire at the headlamp switch.
You are now finished wiring the small head lamp control plug.
Step 3: Wiring the large power plug. This part of the procedure is relatively straight forward and is part wire color mathcing, and part preference and common knowledge.
A. Connect the yellow headlamp power output wire to the yellow headlamp power output wire on the headlight switch using a splice connector.
B. Connect the brown parking and dash lamp power output wire to the brown parking and dash lamp power output wire on the headlight switch.
C. Connect the light blue parking and dash lamp power input wire to the orange parking and dash lamp input wire on the headlight switch.
D. Connect the dark green head lamp power input wire according to either your vehicle or preference. If you wish the low beam head lamps to remain on while having the high beam lamps on or, you do not have a flash-to-pass wire, and/or you do not plan on installing the DRL module, then simply connect this wire to the dark green wire on the headlamp switch. If you do not wish the low beam lamps to remain on, you are installing the DRL module, and your vehicle is equipped with flash-to-pass, connect this to the yellow/black wire on the large plug in the headlight switch.
E. Connect the dark blue daytime running light power output wire to the dark blue wire of the DRL module plug. If you do not want to install the DRL module, you can go ahead and cap off this wire.
You are now finished with the large auto-lamp control plug. You may now want to plug in the controller to test it. Turn your ignition to the "run" position, and, if it is daytime, cover the ambient light sensor. in about 30 seconds to a minute, your headlamps, dash, and parking lamps should switch on automatically. If it is already night time, they should already switch on once you turn the key to the "run" position.
Step 4: The DRL plug and module. If you choose to install the DRL module (or just the plug connector), you will have only one wire to connect.
A. Connect the tan DRL low beam headlamp output wire to the tan low beam output wire after the high/low beam dimmer by splicing it in. This wire should be located under the steering column. If you want to run your high beam lamps at a lowered intensity for DRLs, simply splice this DRL module tan wire with the high beam lamp light green wire located under the steering column as well.
All modules that are preferred should now be connected. To test the DRL module, if it is daytime, simply turn the key to the "run" position. Your low beam headlamps only (or high beam lamps) should now be lit at a lowered intensity. If it is night time, shine a flash light into the ambient light sensor. If your ignition is already in the "run" postion, wait for the normal headlamps to switch off.
You can also use this wire description/pinout to your advantage. If you ever wanted to disable the auto lamps with the flick of a switch, all you would need is a dual pole toggle, rocker, or push button switch and simply connect it in between to the brown and the pink/black headlamp and parking and dash lamp power on signal wires on the small plug of the auto-lamp control module.
I will provide pictures later and hope this helps most of you that have wanted to do this.