Where is the bcm?

It doesn't have an individual BCM, instead it splits the control sections between the front and rear fuse panels. The front is behind the left side kick panel while the rear is in the left side of the cargo area. What is the issue you are having?

Lights, windows, doors and horn they flash and turn on and off

So the headlights only or all lights? The windows go up and down or just stop working? Asking because those systems are split across both modules and it's not likely that both are faulty. This is fully stock? No added alarm or remote start added?

Headlights. Auto up and down doesn't work on windows. Sometimes can only open door with the key even though the door switch inside says the doors are unlocked

The headlights are powered from the fuse box under the hood, They get a signal through the network to turn on the relays. Do they flash at random, or is it a constant timing, like on for a few seconds then off for a few and back on? Have you noticed anything else that follows or leads the flashing? If the flashing is timed it might be related to the door locks not properly signaling the system that they are locked.

Random. Don't notice.

Any codes? Does it have any aftermarket items like remote start or alarm on it? How often do the lights flash? Any other problems than what you listed. From the description you are going to need a scan tool and a scope that can track the networks messaging to see if it is a module acting strange of if it's something like a bad wire or short.

It has the check tpms light on the dash. It has aftermarket remote start

TPMS shouldn't be an issue. However the remote start could be depending on the model and options it has, many can lock the doors and turn on or flash the lights to let you know they worked. Find the unit and get the make and model off the box, then see if you can find an installation manual for it. That will let you see what it can be set up to do, and let you know how to remove it should it be the problem.

Ok thanks

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