lose speedometer reading and trip odometer. on 2000 Volvo V70 XC

Happens sporadicaly when brake light warning light goes on and returns when light goes off. Thanks.

Asked by for the 2000 Volvo V70 XC
Sounds like a possible issue with the ABS. Is the ABS light coming on too?
Yes, but ABS light was coming on and off prior to this issue. Thanks !
Yeah, that's consistent with the symptoms for a defective ABS Control Module. There are companies that rebuild them or you can replace it. An experienced Volvo tech can verify this in very little time.
When the ABS module fails, it can cause the ABS light and Check Engine Light to illuminate, the speedo to stop working, and the Transmission Light to flash. And the Brake light will come on as well.
This is a very, very common problem with you car, so it's not cheap to fix, but it is very easy to have addressed.
Good Luck
I agree with Bret