check your ground going to headlight and parking light.also check headlight ground relay in dash fuse panel. btw this is from a blazer not trail blazer as they didn't make them then. also check your connections for a good connection and power going to connection

I have checked the wires going into the bulb housing, everything seemed secure, I also checked them while my lights were on to see if they came on at all while I was jiggling the wires, got nothing. I will try to find the dash fuse panel and check there. Do I need to remove the dash?

Also, this is a Trailblazer. It is written on the side of the vehicle as well as all over the interior. And the parts I ordered were specific for the 1999 Trailblazer.

Thanks for your reply, I will check into the dash fuse panel and let you know. Any other suggestions are greatly appreciated as well.

I just checked the dash fuse panel, and there are no blown fuses.

the body RELAY block not fuse under dash lh side item 8 and check to see if all the ones that's aren't working are getting power as it may be a relay for that.

this may also be a body control module problem as well. and are you sure you have checked all fuses in underhood fuse box?as well as relays.

My bulbs just got here, and I replaced all the ones that weren't working, and it seems to be working fine for now. It threw me off cause I was very careful not to bang or touch the bulbs while I was switching the assemblies out, and apparently 3 bulbs still blew at the same time. Strange, but glad that's all it was. Thanks for your help.