That is the last piece in the puzzle. I have tested or replaced every other component. I sent the computer off to National Parts for rebuilding. They will test it first and give me the results. Apparently they go bad often and cores are hard to come by. I spoke to a couple of companies that said they had one, but they didn't seem sure that it was the right one and they wanted more cash than the rebuilder.Is that what ended up being defective on your truck?