I own a 2005 Volvo S40 2.4I. This is my first post here so let me know if I need to do anything differently. So my issues started a few months ago and the car has been driven some since the issues started.

The first issue started when I put the car into park I got a warning for a "brake system failure" I was just in a parking lot so I checked to make sure my brakes still worked and it wouldn't let me shift gears. After that I turned the car off intending to just restart it to see if the problem persisted. When I went to turn the car back on it cranked a few times and then didn't start. Then I tried again and there was no crank at all. I then was not able to remove the key from the ignition. I disconnected the battery and reconnected it after a minute. It started up fine and let me take the key out and it shifted fine. At the time I figured it was just a glitch in the system.

Then a month later it happened while I was cruising at about 80 mph when it happened again the ABS and Brake lights both came on. I also got a warning . I was able to clear them by disconnecting the battery again but everything came back after 10 miles. I got it to an O'Reilly's and got a check engine light when I turned it back on there and got 29 codes: P0600, P1719, P0725, 0101, E003, 0150, E000, 0100, DD32, DF11, DE11, 8F02, DE54, 8F01, DE30, 8F22, DE29, DE51, DF17, DE6E, 4F33, 9F32, DE49, 0010, 0037, 0002, 003D, 0005, U0001 . It said the main code was the U0001 and recommended reprogramming or rewiring and checking the connection on the CAM BUS

After driving a bit more I got gas and the check engine light just turned off randomly.

Everything happened again like before with it shutting off and going into limp mode after 100 miles of no light. And then the next morning there was a check engine light with the same codes and then no check engine light the next time it turned on.

I took it to a Volvo dealership to get some input from them. They said they were sure it was at least an ignition switch, but there could be other issues that could be located once that was fixed. I got an ignition switch from a junkyard and replaced the existing one with it. All of my issues still persist so I am not sure what to do next.

Me and my friend are guessing that it's either related to those two modules needing reprogrammed or there is a loose connection or broken wire/exposed wire. What do you think? If it is the CAN-BUS where is that located and how could I check if it's okay.
Thank you,

Forrest

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You will need to be pretty savvy with electronics and logic to figure out your car. Below is from the factory wiring diagram book - showing the high speed bus in your car. Note the same two wire colors are used between the modules. You can find the wiring diagram at

https://volvodiag.com/ewd-online-eng/

There is a guide in the front of the book explaining how to interpret symbols and how to use the book.

One possibility causing your multiple codes/problems is Water or other damage in your CEM. A company such as xemodex.com can fix those. (for usually considerably less than a new one from your Volvo dealer)

Modules don't need to be "reprogrammed". Software does not go bad or the modules don't forget their programming. New modules do need "programming". That is done using a VIDA subscription and a compatible DICE unit.

What to do next - usually involves paying someone to figure out what's wrong with your car. The "got one from a junkyard and it did not fix it" method will be a very long frustrating road if that's the method you choose -

Keep in mind that all your modules are tied to the VIN of your car. Used modules generally will not work. You can't swap them from junkyard cars.

What codes come back first after they are erased with a compatible scan tool? (disconnecting the battery does not erase codes)

 

I just took the CEM off and all the connections look very clean and no signs of corrosion was still going to apply dialectic grease before replacing it. It is very unlikely that it's the battery since I got a new one in between the issues starting and now and they have consistently persisted will check it super fast to confirm that though. Also thought I should mention that I've had issues with the electrical in the trunk as the wires in the bellow were breaking. I rewired that section but am still having issues with it so not sure if there could be other areas where the wiring has gotten exposed and could be causing the issues. Thank you for all your help!