Thank you for all the posts. Wish I had googled this before agreeing to pay $2,300 (USD) at an independent dealer here in CA later today. I'm the original owner of this car which has 150k miles and bought it to shuttle my kids around. Rear cargo window stopped opening a year ago. Interior trunk lights started staying on 6 month ago. 3 months ago the key fobs/locking system stopped working and the windshield wiper would start and stop at odd times while driving and end in the up position. The last straw was the trunk not being able to latch on 12/20. On 12/22 a local bmw independent shop replaced one of the right trunk harnesses (#3 or #4 per diagrams?). The insulation was cracked on several wires and several wires were bent and frayed. Repair shop hoped changing latch would fix latch issue, which it didn't. Probably installed a new $200 latch unnecessarily. Total repair costs came to 8hrs of labor at $140/hr plus parts equals $1600 for replacing one of the right harnesses and new latch... rear window works, wiper works, radio works better, locking system and keys work again, BUT trunk won't latch or open with either key fob or manually. Repair shop said to try opening trunk manually with a little push, but it doesn't work either. Trunk makes a sound like it's trying to operate (groaning). Latch is not releasing, but left side strut is trying to release the hatch. It tries for a while and gives up and stays closed. Back in shop again today. Shop says I will need to replace left side harnesses and they are sure the right harnesses they replaced the other day were fine. They find a "ground wire" that needs fixing so they tell me to replace the whole harness on the left side just for the hatch latch issue. They said replacing the whole harness will also fix the cargo light issue (which I don't really care about). They said they would charge 4 hours of labor for the left hatch wiring harness plus parts... Does this sound correct and fair? This is a lot to spend for us at this time and I'm worried we're spending "extra" unnecessarily. Total costs will be over $2,200 for trunk not latching and unlatching basically. Everything else we could have lived with.

 

You could always try it yourself. It's really not too hard, just a fiddly job. You could buy the bits to do the job probably for about $50. 4 hours sounds about right as it does take some time to get into the wiring harness.