Door locks only work with truck on or in accessory
 

Hello, I have a 2000 Chevrolet Silverado 2500. When I first bought this truck last month, I didn't realize it but the far right connection to the body control module was unplugged. The power door locks ONLY lock the doors and would not unlock the doors. Also, the dome light does not work. When I realized the BCM was unlugged on the one plug, I plugged it back in. Now the dome light works, but the electric door locks both lock and unlock the doors ONLY when the truck is turned on or in accessory position. The electric door locks do not work at all with the BMC plugged in as normal and the truck is turned off. Also, when it is plugged in the door chime dings even when the key is taken out of the ignition.

Do you think this is a faulty BCM? I found one at a junk yard for $50, but if I buy it will i have to take it to the dealer and have to pay them $120 to program or flash it? I have checked all the fuses and wiring and it all looks ok.

thank you and let me know if you have any ideas.