Just purchased a ford navigation unit to go into my 2006 lincoln mark lt

What country are you in ? USA is PATS - anti-theft system ,other country's called securilock system .

You can't reset anything , it's software programmed into the vehicles computers .

Security light flashing when trying to start the vehicle ? Hook up a professional scan tool an check codes .

SecuriLock, also known as Passive Anti-Theft System ( PATS ), is Ford Motor Company 's immobilizer technology. In 1996 the technology started showing up on select models of Ford, Lincoln, and Mercury vehicles. The keys have a radio frequency transponder embedded in the plastic head with a unique electronic identification code.

https://ricksfreeautorepairadvice.com/ford-pats-antitheft-system/


Your best bet , have towed to a qualified repair shop.

On this website (click link below) you find fuse box diagram and description for Lincoln Mark LT

Lincoln Mark LT fuse box Auto Genius

You may have this posted in the wrong product category. Please select another category appropriate to the problem and re-post the problem so the correct expert will see and respond to the question..

You can't do that, the process takes a special Ford diagnostic machine to install the new programs.

For the new body style 2004 ( not the 2004 Heritage or lightning ) there are 3 bolts to remove, and 1 tab, and the headlamp unit pulls out form the front.

From the owners manual


If you did not get an owners manual with your truck ( purchased used ), you can download one from Ford :
https://www.fleet.ford.com/maintenance/owners_manuals/default.asp

YOU NEED SPECIAL TOOLS TO DO THE JOB. BEST TO LET A GARAGE FIX IT THAT WORKS ON FRONT AND REAR SUSPENSION SYSTEMS.

On this website (click link below) you find fuse box (diagram and description) for Lincoln Mark LT

Lincoln Mark LT fuse box Auto Genius

It's possible, was the light out before the audio tec worked on it, if so go back to the guy and ask him if he may have moved a connector or something when working on the stereo. don't go in and accuse him be nice and he will most likely have you fixed in no time.

ITS IN THE BOOTOM RIGHT PASSENGER SIDE