That is impossible to say without a diagnosis. That's like asking what my doctor will have to do to treat my pain. It depends on if it's a stomach ache, hang nail, or I cut my foot off with a chain saw. Here is a copy / paste version of a recent reply to someone considering buying a GM product: My personal opinion is find a different brand or find an older truck. GM is very good at separating owners from their money with sneaky business practices. The Body Computer is built into the radio to prevent you from replacing it with an aftermarket radio when it fails. Since the '94 models I am not allowed to buy radio service manuals or parts so you are tied to going through the dealer and GM's very expensive repair centers to have your radio repaired. When it comes back it must be programmed to the truck by the dealer. Without this radio you won't have cruise control, power windows, and other functions.
It is possible to press the "lock" button on the scanner when it is connected to the truck. You will never know that was done until the day comes that the Body Computer has to be replaced. Pressing "lock" locks all of the computers on the vehicle electrically to the master Body Computer. From then on none of those computers will ever work on another vehicle. That means you can't buy used computers from a salvage yard. You must buy new ones from the dealer and have them programmed there. It also means every computer on the vehicle has to "see" the vehicle ID number from the Body Computer each time you turn on the ignition switch before they will work. If they were locked and the Body Computer must be replaced, all the other computers must also be replaced and have their software installed over the internet. That can run into many thousands of dollars and make the vehicle cost more to repair than it is worth. "Got'cha". There is a reason GM has been having trouble selling their products to repeat customers. They are remaining profitable by bleeding money from their customers after the sale. Volkswagen isn't much better. If you want a more customer-friendly company, look at Chrysler, Toyota, or Hyundai. Chrysler is selling plenty of vehicles but that's not where the profit is made. They aren't sucking money from their customers after the sale like GM, Volkswagen, and BMW. Another trick of GM's is to lock up all of their computer software updates so you must go back to the dealership when a problem arises. They will only allow independent shops to update the software on three computers that can affect emissions because the government mandates they have that ability. For all the other computers, up to 47 total, you must go back to the dealer. Even accessing those three computers and updating the software is very expensive for the independent shops and they pass those costs on to you. Of course you're not upset with GM; you're angry with the repair shop for charging you so much. Chrysler and Toyota make everything available to the independent shops accept the Security System Computer. Their yearly web site access charge and download charges are relatively small. Only Hyundai allows anyone to access their updates for free. Funny, GM can't sell their cars and Hyundai can't keep up production. A 2005 truck could already have "throttle-by-wire" which means a very simple and reliable throttle cable has been replaced with a trouble-prone computer, two sensors, and a motor to run the throttle. This just screams of begging for a lawsuit. Oh, wait, ... That's the same system that had Toyota in the news. You can bet there are going to be more problems. This is a terribly unnecessarily complicated system. We are just starting to see numerous problems and complaints of engines that won't speed up when the gas pedal is pressed. Since this is an electronic system it is very picky about having the correct system voltage to work right. Beginning with the 1987 models, GM went from the second best generator design to the world's worst pile ever and they refuse to improve it. They develop huge voltage spikes that interfere with various sensor signals so running problems are common. It is typical to go through four to six replacement generators in the life of the vehicle. They are extremely difficult to disassemble without damaging parts and there is no way to test the parts to know which one is defective, so you just replace everything.
As you can see, I'm not happy with the way GM treats their customers. If you visit a number of dealerships' sales departments you will also find the GM salespeople are by far the highest pressure. They are very good at telling you whatever it takes to sell their product, otherwise they're out the door.