[ImperialCrown]

Is the chair lift ramp at the side sliding door or the rear liftgate door? The latch has 3 switches on it, any of which could cause an opening/closing/pop-off or draw shut malfunction. It really would need to be read with a dealer scan tool as swapping the modules might just verify that the modules themselves are OK. The door control modules usually aren't the problem.
If this door didn't work before the modifications and electrical part replacements, then I would think that the problem is with the base factory components.
It may be best if you went to the dealer for diagnosis. The latch can still be OK, but not pull the door shut because of other reasons. Many times a switch or wiring fault. sometimes a mechanical binding or alignment fault.
The sliding door (and liftgate) modules are fully addressable with the DRB III scan tool. They can store fault codes and display switch states. There may also be a module software update available.
What is the actual 'P' code for the 'ck eng' light?

 

[vajeeper56]

Ok, the ramp is on the right side. The story gets more curious. Since my last post the ch eng light went out then came back on. However the issues with the gear selector indicator have disappeared. Yesterday the latch seemed to start working! actually it seems fine! Today I went into the back and found the ramp system control computer was off. I turned it on and it is working. I am going to get my sister in law to read the code again tomorrow. See if we get the same or different code.

Now all that is definitely wrong is the right sliding door button is broken.