How to fix ECU is disconnected?

TONYA HUDSON2

MEMBER
1999 CADILLAC DEVILLE
2WD
AUTOMATIC
179,000 MILES

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.

1 Reply

CARADIODOC

MECHANIC
33,752 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