The passenger sliding door on my 2006 T&C stops exactly half way. It doesn't matter whether it opening and closing. It does it every time, it never fails to fail. Manually there is no rubbing or sticking. It operates smoothly.

My Chrysler dealer's mechanic said the wiring harness needs replacing. Does everyone agree? Is there another (less expensive) cause. I would appreciate a second opinion.

 

open the door and look in the wire trax see if U see one broken I am on my way right now to fix just that for a cust

 

Yes, good chance the mechanic is right. That wire harness is a problem for many. A picture speaks a thousand words. A video speaks a million. This shows you how to get at the wire harness and mentions about some repair options:
How to Fix Dodge Grand Caravan and Chrysler Town and Country Sliding Door Wires - YouTube

If you opt for a new wire harness they can be had from Dorman for around $60.

 

Power Sliding Door Adjustment And Diagnosis Aid

Pawl Switch - The pawl switch may behave differently depending on how hard the door is closed. Check the switch reading by closing the latch just to the secondary position, with a moderate slam to full closed (primary), and an aggressive slam to primary. If slamming of the door to primary causes the pawl switch to remain closed when the latch is in primary, Replace the latch.

Full Open Switch - If the full open switch always reads open, check the hold open latch cable to make sure it isn't preventing the hold open latch from contacting the switch. An easy way to check is to remove the hold open cable and then read the switch status with the door fully open. If the cable is impacting the switch status, replace the hold open cable.

Latch Hesitating or Pausing During Cinch - Place the door in the mid point of travel.
Use a screwdriver to place the latch in the secondary position. If the latch still hesitates or pauses during cinch, replace the latch.