Rear passenger-side parking light stays on after the car is turned off. Any hints about what could cause this? My research seems to inidcate its the security module - now can I verify this?

If its the security module - what will it cost to replace the module?

 

Which taillight are you referring to? If its not the brake light, it is not the security module. The other rear lamps are controlled by the Body module. Modules vary in price and can be found at junkers, ebay, or rebuilt from online sources like blag dog. If you, or someone who owes you a big favor is good enough with a slodering iron to tackle SMT devices, I can give you some pointers in repairing your module.