Turn the manual switch to "off" for the headlights to kill the lights, and it will quiet the headlight warning chime.
Another solution would be to check the operation of the plunger switches in the door jambs. They have a single (positive) wire connection, with a plastic insulator that dry-rots, allowing power to go to ground. There are also switches connected to the door latches, if the latch doesn't close, the circuit remains open. I use Electronic parts cleaner to remove old grease and grime, and then use white lithium or HD silicone. Check the post on the door jamb (where the latch engages). It's supposed to have a plastic (delrin) spacer on the metal post. If it's broken, missing, or the latch has cut through it, the door won't close tightly. Leading to water leaks in the rain (or carwash), an annoying rattle, and high-pitched air leaks at highway speeds. No easy way to replace it, the post has to come out. Make sure your Torx bits are Chrome-molybdenum or titanium and covered by a warranty, get out the big breaker bar. A TEMPORARY fix is to wrap the post in layers of electrical tape. The latch WILL cut through the tape and the door will rattle again...
Where is ignition control module on a 2001 mercury sable
Replace auto lamp module.
According to the 2000 Mercury Sable Owner Guide : ( Motorcraft MERCON - V , automatic transmission fluid in both types of automatic transaxle / transmission )
There is a module that controls this. I forget the name of it offhand, however I do know that it is several hundred dollars just for the part. Just not worth it...
The 1991 Mercury Sable ignition switch is held in place with a retaining ring. Loosen the retaining ring. Pull the ignition switch out. Remove the wiring harness from the rear of the ignition switch. Reverse the process to install the new ignition switch.
Those aren't headlights, they're considered running lights or parking lights. I believe that mercury calls this a Light Bar.
The Mercury Sable transmission has a fluid capacity of 12 quarts. You can use any SAE certified automatic transmission fluid.
According to the 1999 Mercury Sable Owner Guide : ( Motorcraft MERCON-V automatic transmission fluid ) ( to confirm the type used , it should be engraved in the automatic transmission fluid dipstick )
13.8 - 14.4 volts DC,13.82 with engine running and headlights on!
According to the 1998 Mercury Sable Owner Guide : ( Motorcraft MERCON-V automatic transmission fluid )
According to the 2004 Mercury Sable Owner Guide : ( Motorcraft MERCON automatic transmission fluid is used as the power steering fluid )
I believe that wire is for the key is in the ignition warning buzzer! Not 100%, but 90%.