2005 S80 throttle problem

[snyggis]

My 2005 S80 has the same ETM problem that has been reported in 1999-2001 models. I am driving along on the highway at 65 and all at once the speed drops to about 20-30 mph. I goes into limp home mode. It is scary. This has just happened for the third time. The car is now at 85,000 mi. The first time it happened I was just happy to get it fixed. The second time the warranty on the part had just expired. I bit the bullet and paid it again. Now the third time, 5 months after the second time, the ETM is still under warranty. But this time, the dealership tells me that Volvo requires that they change the wiring harness as well. That will cost $900 more. The explanation they give describing the relationship of the wiring to the problem simply does not make sense. I said please just replace the throttle. The dealership refuses to replace only the throttle without the new wiring. Does anyone else have any knowledge of this? Thank you.