Electrical lighting main lights will not turn off after leaving vehicle

The cruise control system on this vehicle uses mechanical, electrical and vacuum operated components to maintain vehicle speeds over 25 MPH. The cruise control unit receives command signals from the cruise control main switch and the set/resume switch. It also receives operating signals form the brake light switch, ignition coil, speed sensor, clutch switch (manual transmission) or shift position switch (automatic transmission). If the main switch's indicator light illuminates when turned on, it's likely working properly. Likewise, if the cruise control light on the instrument cluster illuminates when the set/resume switch is pressed, it is likely OK. At this point the problem would likely be mechanical or vacuum-related rather than electrical and the actuator/servo would be the prime suspect. On the other hand if the cluster indicator light is not illuminating, it could be an electrical issue such as the set switch not registering or one of the safety switches (brake switch, clutch switch or shift position switch) registering inappropriately which effectively cancels the cruise request. You can read more here: https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-cruise-control-switch

Not sure what your meaning of why need to reset the computer, the alternator has nothing to do with a check engine light so if that is the issue with check engine light need to scan vehicle find what code is fix that if what to know how to dead boot computer 1.pull + battery cable leave off 2. Get in vehicle turn lights on yes I know there not going to come on we are draining the capacitors in computer 3. Leave light switch on depress brake several times 4. Insert ignition key turn like cranking vehicle couple times. 5. Turn everything off lights key an reinstall + battery cable start vehicle check engine light should be off. Basically that is a dead boot for computer draining all power for it.

How's the battery ? Cables an connections ? Sounds like main power supply problem , do the headlamps light when you turn them on ? Dome lights light when you open a door ? Do you know how to test automotive electrical circuits ? Do you know what a wiring diagram is ? an how to read one ?
Electric Testing Techniques You Need to Know
Find a wiring diagram an test main B+ voltage supply to the ignition switch ,in an out at run an start positions !
If the key won't turn off with out pushing that hidden button you have a problem with power to the shift inter lock system . GM did have ignition switch problems on some year vehicle's !

Maybe the tail light are not fearthed properly to the body of the vehicle. With vehicle electrics, the main body of the vehicle is used as the earth.

i had the exact same thing happen to me with my first car, a 1966 mercury comet.

i replaced the fuel pump, rebuilt the carburetor (twice), and finally rebuilt the entire engine! still, every time afterwards, the car ran ok, then would cut off again!

it turned to be just a $2 clogged fuel filter. i' suspect the same with your vehicle. after removing the filter, simply blow through it. any resistance, means it needs replacing.

There is a lot involved in the electronic's on your vehicle , FEM - front electronic module ,REM - rear electronic module , the instrument cluster is a module also . The main light switch is a input to the instrument cluster , the instrument cluster is connected to the FEM - REM via a serial data network . Could be that your problem is a simple wiring issue , shorted to ground , shorted to B+ voltage etc.... Then again, could be one of these modules is acting up. Checking the wiring harnesses for bare spots ,rubbing on body metal parts etc.... Checking for DTC'S - diagnostic trouble codes in all the modules on the vehicle ,not just OBD2 , need a professional type scan tool to do that. Viewing wiring diagrams an testing electrical circuits with a DVOM - digital volt ohmmeter . Do you know any of this ?
Free wiring diagrams here http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine . Under system click on lighting ,then under subsystem click on exterior lighting . Click the search button , then the blue link.
Basic Electricity for Service Techs Ohm law Current Flow Opens Shorts
Electric Testing Techniques You Need to Know

does the word security stays flashing after you crank the engine? if it does vehicle has a problem with the passlock 2 system which is a factory installed anti-theft system. when faulty which is too common on those year GM models, vehicle will start and run for 2 or 3 seconds and die out. follow this procedure: 1) locate yellow 20ga. wire running out of steering column which will run along with heavier gauge wires. correct wire will be thin compared to the main ignition wires. 2) cut wire and connect an in line toggle switch and leave in on position. 3) put key in ignition and move forward and leave it that way for approximate 15 min. or until security light goes out. 4) as soon as light goes out vehicle should start. if it does not crank engine again until it starts. 5). when engine starts flip toggle switch to the off position then security light will come on. done. passlock system is bypassed. security light will stay on constant but vehicle will no longer leave you stranded.

change the bulbs if not there a switch is on the brake peddle it could b it

I'm not familiar with your type of vehicle, but:-

Look for a 'fusible wire link' that may be down near the starter motor battry power connection cable. If fused, it will be melted.

Most vehicles hase either a fusible link or a high power fuse in between the battery output and the main vehicle distribution power bus.

Hi I am Vortash i suggest that you spray all your electrical connections plugs etc with a switch cleaner fluid .. Not wd40 .. but an actual electrical contact cleaner . Check your Battery Earth connections and battery terminals and all fuses and relays spray with the cleaner also . Check the engine to body earth strap and your main ECU plug .. hope this helps regards Vortash