Engine not starting

When the battery is re-hooked up, the loud fast clicking starts and is coming from a relay under the dash. When the key is inserted into the ignition and the doors are open, the sound changes in tone to appear to indicate the doors are still open. The security light flashes quickly and continuously before the key is inserted. Once the key is inserted the security light stops then again starts to flash. Nothing changes whether the vehicle is in park or neutral. The sound or clicking is coming from a relay under the dash. The relay itself appears to be connected to the computer. There is a line running directly to the computer. I replaced this relay with a new one and the problem continues exactly as it was with the prior relay. To me everything points to another computer gone bad.

Already completed and it falls within those same parameters. Thanks.

Ken, sorry for my delay. The clicking sound is coming from the relay module that has a line running to the CPU. The relay is under the dash near the firewall directly behind or in line with the CPU. Tried replacing this module or relay and the new one does the same thing. The ground is the first thing L looked for but so far, if it is the ground I can not locate the problem or bad wire or whatever. Giving up at this point. I neither have the knowledge nor the time to remove the entire dashboard to track down the problem. I do not have the time or the finances to replace CPU and reprogram the truck. Already had that done a few years ago and it turned out to be an expensive project.

Thanks Ken. Will do.