Multiple warnings on startup

[jagman1]

I've been having the following issues for about a month, and still don't have a solution. I'm posting here to broaden the knowledge base I'm using to try and figure this out. Here's the problem ('04 CTT):

Start the car (it starts right up), then a series of warnings appear: Air suspension, brake proportioning, AWD failure, PSM failure, and PRND is either blanked out or highlighted (as if all gears are currently selected). During this time I can't move it out of park.

After idling for about 30 seconds, all the warnings clear on their own and the car is 100% perfect. No issues whatsoever.

So far I've replaced the battery (single battery CTT) and it didn't change anything. Durametric is showing errors in all the modules that I've listed, but all the errors are the same, "CAN Bus No signal/no communication." The only other code that is new is in the Vehicle Electrical section of Durametric. It is code 576 for Terminal 15 implausible signal.

When I clear the codes they all clear and do not return. If I restart the car and the failures appear, the same codes get set, and the cycle repeats.

The errors never return during a drive. Every time I start the car, I have a 50% chance of getting the errors. The other 50% of the time, no errors and everything is normal.

[hahnmgh63]

Any mods (electrically oriented) ever done to the vehicle? Wired in Radar detector, Alarm, etc... Sounds like a CAN issue or Battery Regulator, Central Electrics. A lot of connections for the CAN bus to check. Once again, any mods or electrical work done that you know of?

[jagman1]

No mods. I've had the car for 5 years and there have been no equipment changes or other issues in that time. I've checked under the front carpets for signs of water intrusion and found it completely dry. No signs of ever suffering a leak.

[jagman1]

I've finally sorted this out. It ended up being the Terminal 15 relay under the drivers seat next to the battery. It turns out this relay is responsible for powering the CAN bus and had an intermittent fault.

Total cost $18. And 15 hours of my life searching for it.

Thanks for all the suggestions along the way.

[RFM]

Thank you for the explanation, other members can benefit from it.