How to fix ECU is disconnected?

1999 CADILLAC DEVILLE
179,000 MILES • 2WD • AUTOMATIC
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TONYA HUDSON2
  • MEMBER
  • 15 POSTS
Anti-theft system was engaged. I was able to fix that problem. Now it's reading the ECU is disconnected. I never had a key fob programed to the car. I ordered a few of them and tried to program it and when I ran OBD2 reader it read ECU disconnected. I'm not sure what to do from here. Please give me some advice on what to do or how to fix the problem.
Mar 4, 2022 at 9:19 AM
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CARADIODOC
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  • 34,306 POSTS
Hold on. I doubt you have a problem with the Engine Computer. If the engine is running properly and the Check Engine light is not on, chances are it's a code reader problem. We see this complaint here every day that a code reader won't communicate. Sometimes it's due to a blown fuse in the car. Sometimes it's just a software problem. This usually affects simple code readers that typically cost less than $100.00. A full scanner is likely to work. Most people don't have their own because they can cost from $3,000.00 to as much as $10,000.00. If you can find a mechanic who is willing to try his scanner, that will prove this is an application problem with your code reader.

Here's links to some articles you might find useful:

https://www.2carpros.com/articles/how-to-re-program-a-key-remote-fob

https://www.2carpros.com/articles/how-to-reset-a-security-system
Mar 4, 2022 at 11:19 AM