V70XC ABS troubleshoot

[FWDXC]

Hi all,

I have a MY 2000 V70 XC (280k km on odo) and am looking for some troubleshooting input regarding ABS. The car has lived in Canada all its life and was not rust checked - so some meaningful corrosion on the underside. Body, is straight, interior clean, engine runs strong. Rear drive shaft has been removed as angle gear was worn and slipping. Front rotors have been replaced (genuine Volvo parts) along with new pads all around in the last 16 months. I'm keen to get this fixed, but reluctant to throw a ton of money at it.

Symptoms:

-ABS pump motor intermittently audible above 30km/h
-Inconsistent, grinding pedal feel impacting brake performance. Usually clears with a couple pumps then stops normally.

Troubleshooting to date:

-ABS / Tracs lights have come on only once more than a year ago and not again since
-Diagnostics codes were reset 10months ago by indie Volvo tech
-Autel619 OBD reader currently finds no ABS/SRS codes (or any other codes) stored, pending or otherwise
-No obvious play in any wheel bearing
-LF Drive shaft replaced ~24 months ago. ABS ring is mint.
-RF Drive shaft is likely original. Condition of ABS ring is questionable. Many teeth are flaky / corroded. I've cleaned these with a brass brush to remove debris etc with no noticeable change
-Wheel speed sensors are clean. Wiring harness seems to be intact from visual inspection.

I know the ABS module is prone to failure on these cars as they age, but am uncertain how to confirm this to be the case without ordering a known-working part and making the swap, and am reluctant to make the swap without being more confident it's the fix as it's quite possible the E5 torx bolts are corroded in place / will snap.

How far gone is too gone for an ABS ring to function properly? How can one test functionality of the wheel speed sensors? Does anyone have any further diagnostic advice?

Thanks in advance,

Neil

[jimmy57]

The digital wheel speed sensors on that car can only be easily checked with a scan tool with ABS capability. VIDA being the best. You drive with VIDA operating and look at the 4 wheel speeds to see that they give the same speed as you acclerate and then drive up to 100 kph and then slow back down. Then hit some bumps at lower speed to see that they stay the same in that situation. The wheels speed sensor rings can be inspected visually but that requires some disassembly and mirrors.

[wizechatmgr]

Was there any slop to the roads during these events? The TRACS system could still engage even though you've disabled the AWD.