C5 corvette problems

Not a Corvette expert, but I don't think sunlight would have any effect.
The motors should close the doors when you turn the lights off regardless if it is dark or not.
Are the headlights staying on, or just the doors staying up ? The up position is the default when something is wrong, so I think it takes voltage to close them.

make sure the interior light switch is turned off so they only come on when the door is opened(this happens alot),the next thing is it could be a door switch that has a problem thinking its open.you could also have a headlight switch that has an internal problem like a short that is allowing power to the interior light wire circuit of the switch causing the interior lights to stay on.

Do you know how to test automotive electrical circuits ?
When the headlamp switch is turned to the HEAD position, battery voltage is applied to the headlamp opening door actuator control module through CKT 103. The LH head lamp door opens when battery voltage is applied to the LH headlamp opening door assembly through CKT 576 and ground is applied to CKT 577. The RH headlamp door opens when battery voltage is applied to the RH headlamp opening door assembly through CKT 578 and ground is applied to CKT 579. When the headlamp switch is moved to the OFF position, battery voltage is applied to the headlamp opening door actuator control module through CKT 306. The LH headlamp door closes when battery voltage is applied to the LH headlamp opening door assembly through CKT 577 and ground is applied to CKT 576. The RH headlamp door closes when battery voltage is applied to the RH headlamp opening door assembly through CKT 579 and ground is applied to CKT 578. Battery voltage is constantly applied to the headlamp opening door actuator control module from the HDLP MOT L MiniFuse® #4 (CKT 2940) and from the HDLP MOT R, MiniFuse #3 (CKT 3040). The headlamp opening door actuator control module is grounded by CKT 150 through Splice Pack #100 to G102.

Headlamp Doors Do Not Close
Install a scan tool and go to the BCM input display.
Monitor the headlamp off switch status.
Turn the headlamps on and off.
Does the scan tool indicate the headlamp off switch inactive and active?
--
YES - Go to Step 4
NO - Go to Step 6
4
Disconnect the headlamp opening door actuator control module connector C1.
Connect a DMM from connector C1 terminal D to ground.
Measure resistance to ground of circuit 150.
Is resistance within the specified values?
0-2 ohms
YES - Go to Step 5
NO - Go to Step 9
5
Connect a test light from the headlamp opening door actuator control module connector C1 terminal C to ground.
Turn the headlamp switch off.
Does the test light illuminate?

The problem is with the door switch. It should be mounted on the door post. You either have a bad switch or a broken wire.

Check the switches screwed into the frame of the door. switch could be jammed. You should be albe to push it in and out.

EATHER YOU HAVE A BAD GROUND OR A BAD HEADLIGHT SWITCH

Sounds like each bulb has 1 bad element. Unusual, but possible. Those bulbs are tricky to change but you can do it.
Turn your switch on and turn on the headlights. While they are still up, turn off the switch so that they will remain in the up or open position.
Next to each headlight assembly, you will see a rubber hood stop that can be easily removed with open ended wrench. With those stops off the car, it is a snap to reach down, next to the headlamps to the back of the parking lamp socket and remove it by turning conuter clockwise. Replace with the correct amber bulbs (available at any auto parts store) and your problem should be solved! Note.......be CERTAIN to check all fuses 1st. Good luck!

check the wiring between the door and body it may have gotten brittle and cracked or broken this would explain the intermitten lock function

Your headlight motors are bad. Pre-87 cars had a terrible problem with this, upgrade them to the 87-up style. Firebird/Corvette motors are the same.

Hi ! You have to check for loose or dirty ground wire.