I have a 2000 Blazer LT. The accessories
(as in radio, lights, power to windows and sunroof) don't turn off when I open my driver's side door after turning the truck off. They turn off when I open any other door. I tried replacing the door pin, no luck. If I unlock the driver door with a key and unlock the doors from the inside and open the backdoor the security alarm goes off. It seems like the truck isn't registering that the driver's door is open. Is the sensor in the door latch? I read somewhere that there may be a sensor for this in that latch on these models. Any ideas would be wonderful.

2nd problem is that my fog lights don't work. They are stock and I've replaced the switch assembly, light bulbs, tested the relays, and for power at the switch but they do not turn on when I hit the button. I'm at a loss on this one.

 

The fog lights will not turn on when the high beams are on. They should be functional if only the park lights or the low beams are on with the park lights.

As far as the driver door goes, covered that in the other thread you responded to. There is a switch in the door latch as well as one at the key cylinder in the door that both get used by the alarm system. In one of the more recent threads discussing the CTD (content theft deterrent) system, I posted a wiring diagram. A search for "CTD+wiring" should turn that up.

 

I haven't been able to get my fog lights to turn on at all. Relay is good, bulbs are good, switch is good. They won't turn on when the daytime runners are on or the low beams are on. I've been doing a bunch of work on it but they didn't work beforehand and they don't work now. I think I'll take my multimeter thingy and see if I get current like I'm supposed to in the fuse box in the engine compartment. Thanks for the tips

 

Does your RPO code list have a code describing fog lights? If not, maybe someone added them, but never had the truck reprogrammed to activate them? You can plug your VIN into compnine.com's vin decoder and it will give you a list of all RPO codes for your truck as well as their descriptions.

 

I checked out the compnine.com. I did find this RPO code ANLPACKAGE,AIR DEFLECTOR AND FOG LAMPS A/DFL & FOG LP PKG(ANL) which describes stock fog lights. That's a pretty awesome website. I've heard of it before from my dad (auto shop owner/mechanic) but I hadn't thought to use it for this.

 

If your DRL's are working properly, then the FOG LP fuse is doing its job. From there, power runs to the fog lamp relay to power the fog lamps when the relay is switched on. The relay gets is power from the park lamps relay and it's ground from the body control module. So the park lamps must be on for the fog light relay to have +12V power on the control side and the BCM must complete the ground to the control side of the relay for the relay to pass +12V from the FOG LP fuse to the fog lamps themselves.

The fog light switch is a momentary switch that, when pushed, completes a ground circuit to the BCM to tell it to turn on/off the fog relay control output. If there isn't ground on the black wire to the fog lamp switch, it wouldn't be completing the ground circuit to the BCM which would result in the condition you are experiencing. If the ground to the fog lamp switch were bad/disconnected, the back-lighting of the switch would not work either. So with your park lights on, if the switch is back-lit, then the ground is good and you need to test continuity from pin E to pin D on the switch with the plug disconnected & the button depressed.