I Just wanted a memory refresh bob .
The car does a system check when first started which takes some time , and this is why problems show up when you’re driving down the road .
Iirc , starting the car in neutral means the system check does not start .
I think this was more for tiptronic faults than abs faults though , and might even be for getting it out of 3rd gear limp mode ?
Tip faults are much harder to fix as many inputs used from engine etc .
This is not happening in this situation , and I honestly think this thread will die once the proven bad wheel sensor is replaced ….

O/T ; Any news on that steering rack you was going to look at for me ?

THx Ian. I'll do the neutral test. What are thoughts about what that might show?

I've thought that maybe it is the FCU if everything in the signal chain is thumbs up after the new sensor is installed. Do you know if a code would reveal an FCU failure( or for that matter any of the ABS relays? ).

New sensor 964 606 403 02 came Friday.
Will put on this week.
Had the car out for drive and tried the neutral start.
Tip won't let you start except in P.

Ok. Been a while but will have an update in2 weeks.
PROGRESS!

So - here's where we're at.
I replaced the left front wheel sensor. Got good output but appeared to make no difference in the signal chain. Still had ABS lights and buzzer.
Then reseated every ABS relay- no difference.
So I decided to just replace the R34 ABS relay. 928 615 124 03.
Call it dumb luck, but ABS warning light and buzzer stopped coming on (nor coming on after warm up).

Still no speedo, cruise control, spoiler, and the tiptronic was doing the normal fault switch to auto after 3-4 minutes (consistently). So after reading here more, and Rennlist and talking with 30 yr experienced porsche mechanic, he suggested simply change out the R52 FCU relay which converts ABS signal into signal that drives speedo, spoiler, cruise and tip.

Found a new one 964 618 220 51 for $245 and decided to bite this bullet.
Now I have speedo and spoiler back. Tip still consistently in this fault mode, but for a longer time, so I'm suspect its not simply FCU output issue. And no cruise control.

More digging, reading and talking. Of suspect was either the tip control module, tip shift switch or combo of both. There appeared to be a higher likely hood of the TCM fault than the tip switch. Shopped around for a used TCM, got it in, and now I have the tip the working normally again. I will keep eye in the tip shift switch. Per my mechanic friend they (and PDK) shift switches are susceptible to fault with age).

On to the cruise control. Cruise is fused at #19. So are the brake lights. I have no brake lights and no cruise. I thought cruise would be resolved with the FCU replacement. Fuse was blown, replaced it and immediately blew again. Twice. Put 12v on the brake switch and had brake lights SO brake switch and wiring to the lights is ok but somewhere between fuse panel and brake switch I suspect there is short. Chaffing? Critters? I am going to start a separate thread for that issue. So if I find/fix the short and still have no cruise, that's a whole thread as well.

So this little adventure has brought a new wheel sensor, #34 ABS relay, #52 FCU relay and used TCM. Brakes light and cruise control next.