2013 Cadillac XTS, random misfire, random codes from all over the vehicle

Dtnel wrote:

Make sure you get the ecm programmed if you can prior otherwise make sure you have the proper equipment for when you do it. Have you swapped any electric parts on this vehicle lately that maybe weren't mentioned here?

Did you try disconnecting the battery cables, letting it sit 10-20 min to see if maybe the computer needs to refresh itself?

I can't recall if I'd mentioned but I recently had a '12 CTS 4 door I did a key & remote on with a ton of codes. Disconnecting the battery helped. As a matter of fact I have to drop keys by car dealer tomorrow so can get paid. They're not going to like the fact that the remote start & trunk don't work and this is a OEM replacement remote.

I called the dealership and they said this was a remote start vehicle from the factory, lights for remote start and trunk button flash but they don't work but they cause the taillights to flash when button is depressed so it's getting communication so it shows the remote is communicating properly with the car RKE system.

I have the proper remote as well as the dealer gave me the part number. There's probably something wrong with one of or both of the systems that aren't working. We'll see soon enough. Don't think they want to pay me the extra $80-$100 for diagnostic so I'll drop my keys & move on after I get my cash / check

Dtnel,
Yes, I was able to order an ECM that will be programmed to the VIN. I ordered from Pro Tech Auto Systems in Florida. They have been on my radar for a month or two and they have great reviews. Their computers aren't cheap but that's OK as long as they stand behind the product.

No other parts have been replaced without being listed. The only parts replaced are a coil that made no improvement and then back in July I replaced the CUE screen. Today I removed the stereo/CUE console to make sure I hadn't pinched a data wire, everything looked good in there. I didn't start having problems until October.

Last Sunday I disconnected the battery for an hour or two while I checked the grounds and connectors under the hood. I don't think it made any difference. It's a tough to troubleshoot because the problems are so intermittent.

Hopefully the CTS with additional problems will be handled by the dealer. I own an RV repair shop and only work on my personal cars (I enjoy the challenge most of the time) but some customers don't understand a problem can pop up at any time with an unrelated component and it doesn't mean we caused it. We winterized a motorhome in November and called the owner because he had a ruptured boiler tank in his hydronic heating system causing antifreeze and domestic water to mix. He insisted it had worked fine the previous week and it probably did but it now had a hole in it. He wasn't 100% convinced we didn't do anything to cause this but he did pay us to get everything back in working order.

I received the used PCM and although it is programmed with the VIN, it still needs a crank relearn so the car is at an independant shop waiting for them to get to it for the crank relearn. Recently it has been acting up pretty bad with more misfires than ever and other random BCM type codes. The shop has it on their schedule for this Thursday, March 4th but they are hoping they can get to it sooner because it's sitting on their property.
Hopefully this is the end of the trouble. We'll see what happens!

I left my car with my mechanic for about 3 weeks. He swapped the ECM with the reman I bought and he tried to perform a crank relearn but said the reman ECM had a dead miss on cylinder 5. The rebuilder sent a replacement ECM and I still have it but haven't swapped it out.
My mechanic drove the car as much as possible and couldn't make if fail. I've been driving it ~3 weeks without any trouble until tonight.
Primary code is a PO302 and it is a consistent miss. Other codes include U0168 lost communication with vehicle security module, U0401 invalid data received from ECM, U0100 lost communication with ECM.
There really seems to be a correlation (confirmed by the 3 freeze frame reports) with a full tank of gas (91.4%, 80.8%, 91%) and cold weather (ambient 0'F,0'F,27'F) when these events happen. Nearly every time this happens I had filled up with gas the same day. I was able to pull the freeze frame data and have attached it to this post. This is only the third time I have been able to capture the freeze frame data.

Any suggestions would be much appreciated. I realize this is a tough one to troubleshoot because it is so intermittent.

gimmick1 wrote:

Nearly every time this happens I had filled up with gas the same day. I was able to pull the freeze frame data and have attached it to this post.

That's what I was noticing earlier. Go top off the tank and see if your miss comes back.

Tyler, somehow I missed your post in February mentioning the fuel tank level. I did fill up today and everything went well on my drive home. The ambient temperature was ~28 so maybe it’s a little too warm for the gremlins to come out. Thank you for your help. I’ll keep posting as more information becomes available.