2000 Volvo S80 torque clutch slippage
 

Hello everyone,
I have a 2000 S80 has 124,000 miles on it.
My question is when I'm traveling at speeds of 60 miles per hour the overdrive feels like it's either slipping or engages and disengages . I'm hoping that changing the fluid and filter just needs to be done.

Transmission shifting update.
 

Since I'm not getting much help with any suggestions I'll keep you posted on any updates.. just in case someone else has problems...
I bought the car in August for $750 transmission was slipping, and got the code for solenoid B error code changed the fluid and filter twice already and haven't seen the code since (also used seafoam for automatic transmission) I'm guessing that the filter needs to be replaced one more time. I hope this helps anyone having the same problem. I will give you an update when I get a chance to do it.

Update
 

Transmission is shifting the way it should, I think it's a problem with my abs module or the harness, and,or the throttle body module . I will give you a update when I can.

Are you talking about the torque converter clutch? If they slip it will set a 1870 code.

Torque converter clutch (overdrive clutch)
 

No codes as of yet, the only codes that I got is when I first got the car , which was a solenoid b issue, but hasn't come back since. (I've done 2 fluid and filter changes) But I think I have a bad TPS or dirty throttle body.or both.

Problem is figured out.
 

I pretty much figured out why my S80 is shifting in and out of overdrive .
I think the bcm needs to be replaced. I get a ABS pump motor code a lot ( I have my own Scan tool)
Service abs system on the information display, lately the Abs seems to be working ( but doesn't last) because information display says 0 messages when I start the car sometimes. And the car will drive great. Soon as the service ABS message pops up, it starts hesitating and has the overdrive issue with this message displayed And I haven't gotten any transmission codes for the past two months.I worked on my own cars for 20 years and got okay with trouble shooting different issues . I don't know everything , but learned that when one system acts up it can have a effect on the other systems with these cars . I'll get another abs module soon and give an update. I hope I'm right.
Thank you.

So hard to diagnose cars by text. It almost sounds like you have a bad ground. Multiple random codes affecting more than 1 system.

I'll look into the possible ground issue, but the only code I get is a abs pump code faulty signal. I can buy a rebuilt abs module for $100 with a 5 year warranty on eBay. Thank you for the advice.

The new replacement abs module took care of the abs codes. The transmission is going into overdrive most of the time (still no transmission error codes) my next move will to try to clean up the throttle body and maybe replace the TPS . Then I'll move on from there.
P.S. Could I just need a software update since one hasn't ever been done to the car to the best of my knowledge, and since I haven't gotten any transmission codes ? Thank you.