If there's a "security" light on the dash, or one flashes and the horn honks when you use the remote key fob to lock the doors.
If the vehicle has the factory anti-theft system, you can use any Engine Computer and any Body Computer of the correct part number or application. The anti-theft programming is in both of them. If you install a replacement computer with that same programming, nothing will change. If it doesn't have that programming, it will learn it from the other computer the first time you turn on the ignition switch, then everything will be back to normal.
The potential problem comes in when the vehicle doesn't have that system. Then you MUST install a replacement Engine or Body Computer without that programming. That can be impossible to know with a salvage yard computer because they rarely know which options came on that car, and if they did, that doesn't get recorded on their inventory list. Professional rebuilders may be able to reset that programming but there is no way to do that at the dealership or for you and me. Once the programming has been upgraded to anti-theft, it can't be undone.
If your truck doesn't have anti-theft, and you install a used Engine Computer with it, the Body Computer will learn that programming as soon as you turn on the ignition switch. At that point the engine won't run because both computers are waiting for the disarm signal that's never coming. The typical symptom is the engine will start and run for two seconds, then stall. The only way to solve that is to replace both computers at the same time with ones that don't have the anti-theft programming.
If your engine runs longer than about two seconds, then stalls some time later, that is not a theft system problem. Then the most common causes are the crankshaft position sensor and the camshaft position sensor.
Wednesday, November 14th, 2012 AT 1:04 AM