Yaw sensor code -> No ABS
 

Ok hive mind, I've searched and I'm not finding any help on this (maybe my Google-fu is week).

2013 FR-S, motor swapped (still subie - we don't think this is the issue but are open to ideas), caged racecar, stock ABS module and calipers, etc.

ABS stops working in a session and when it happens, the only consistent-every-time code is the Yaw Rate Sensor.

Sometimes we can come to the pits and reset everything at the battery and the ABS comes back, then she'll run for a full session with no issues. Driver change and the next session out, 3 laps in bang the ABS goes out and stays out for the entire session. ECU/engine reset/refire never fixes it.

Saturday night I drove 6.5 hours round trip to borrow the right ABS module (block and CPU). We swapped the black box/CPU (not the block). That seemed to have no positive effect - same issues, same code.

Question 1: is the Yaw Rate sensor in that ABS black box, or is it elsewhere?
Question 2: any ideas as to what we might be fighting?

Did you move the ABS module at all?

Have you tried calibrating VSC?

No, mounted identically.

Yes, full calibration at the event when we struggled with this.

I been thinking about this for a while. Do you have anything like a datalogger plugged into the OBD2?

I know @RZNT4R has mentioned that plugging something like a scantool can cause ABS codes. Wonder if you have something like that going on.

https://www.ft86club.com/forums/show...5&postcount=25

I WAS going to say yaw rate sensors are typically external to the brake control module, usually bolted to the floor of the car under the driver's seat or centrally below the center console, but the shop manual is making a fool out of me, the relevant DTCs refer to it as being internal, system diagrams show no external sensor and there is no remove/replace header for a stand alone yaw rate sensor.

Huh,I guess I'll go to bed less dumb tonight.

The OBD scanner glitches throw Uxxx communication codes, not this type of stuff.

this guy seems to have lived the same issue and just resolved to remove the fuse. I would still have liked to look at the freeze frame data for some base vitals like control module voltage. Since this happens at the track the unit may be working very hard, can you point a IR thermometer/thermal imager at it when the issue surfaces?

I remember that thread. The yaw sensor is indeed inside the ABS unit. I don't appreciate freeze-frame data nearly enough. That's good stuff.

Have you scanned the chassis codes? What are they?

A thought IF one of the codes is the steering angle/sensor.
The clockspring/steering angle sensor is easily damaged and/or replaced incorrectly. The previous owner had damaged the one in my car causing it to show a bunch of errors including a bad wheel speed sensor. Replacing the clockspring/steering angle sensor, then calibrating the system eliminated all the codes including the wheel speed sensor which wasn't actually bad. However I wouldn't guess this to be an intermittent issue.