Don't have an RS but I will ask a few questions.
Judas, the sensors are adjusted by a shim pack for proper clearance. Have you removed the sensor and are there any shims being used?
Next thing I am going to ask, what do the front brake calipers have on them. Brembo or BMW? Just trying to verify what braking system is installed, ABS-II or I-ABS The P/N you listed is for the servo assisted I-ABS so I would expect to see BMW calipers.
Can you look at the sensor ring also. Equating some of this to the LT and not the RS but probably very similar systems. Is the sensor ring cast metal or stamped sheet metal. It is possible that if the sheet metal type used on the I-ABS, it is installed on the wrong side of the brake rotor if it was ever removed but that is only a guess for a large clearance. Not sure if an earlier RS wheel with the cast sensor would fit but if it did, the sensor gap might be totally wrong in that case if it was farther away and not impacting the sensor with too little clearance.
I guess I also should ask, is there a problem you are trying to resolve? ABS light on and doesn't go out or such?
Thank you for your response.
I have removed the sensor, there are no shims.
The calipers are marked BMW, I believe it is I-ABS.
The sensor ring is stamped, and was installed between the wheel and the brake rotor. Looking at a parts fiche, this appears wrong (the factory manual did not specify, only stated "put parts back in reverse order of disassembly.")
The problem I am trying to solve is both ABS and Red Triangle lights flashing alternately, and ABS not working.
After relocating the sensor ring outboard of the brake rotor, and shimming the sensor to within spec., my symptoms have changed somewhat.
Currently, with key on, I get ABS light on, red triangle off.
I hear servo actuate, etc.
If I start engine and begin driving immediately, the ASB light goes off after a few feet, and I'm pretty sure the ABS is functional at that point.
After 30 seconds or so (either driving or just key on) the system returns to alternately flashing both lights.
I have checked fluid levels in the rear reservoirs, but I have not yet checked front (heading out to do that now.)
With key on, engine off, I hear servo whine when actuating either brake -- I'm led to believe that is a good sign...?
I have not yet flushed and bled the lines -- I expect that to be entertaining, but I have an SBS vacuum bleeder, so maybe not too bad?