2000 Blazer 4x4 LT help

Just picked up a 2000 blazer for my daughter. I did not notice this when I was looking at the car. Here goes.

When I start the car all the lights come on meaning the front head lights, dash lights, rear brake lights and license plate lights . Seems the dash light switch does nothing when car is started but when ignition is in the off position the light switch will work the lights. Th dash dimmer will dim the dash lights. It just seems when the car is started that all the lights come on. She had another 2000 that got totaled and don't recall all the lights coming on when car ignition was on . Any suggestions?

Thanks

Gonna answer my own post. Yes it was daylight out forgot to mention that.
Well the dash sensor might be bad so some post mentioned to remove the driver side dash speaker grill and take plug off sensor and add 1.2k resistors.
Well i did what i did on a 98 blazer i had i removed the under hood fuse/relay box cover and on diagram is the relay for the lights for daytime. I just bent over a tab and put back in socket and back to manual lights.

try this info http://www.geocities.com/zq8gmcsonoma/drl.html