Yaw sensor and braking trouble at track - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

ZDan · 09-14-2020, 03:08 PM

Weird day at the Glen...

Got a VSC light at track. Then massive left front lockup going into 6. Had an off. With damage

Had thrown yaw rate sensor code.

Took it back out, did a few laps up to 7/10ths, was fine for a few laps, then vac light came on again and brakes went slightly nuts again, but fortunately no off.

Thinking about disconnecting ABS to prevent but looking for ideas...

WTF...

NoHaveMSG · 09-14-2020, 03:09 PM

Running PD?

kinghurl · 09-14-2020, 03:15 PM

Quote:

Originally Posted by ZDan

Weird day at the Glen...

Got a VSC light at track. Then massive left front lockup going into 6. Had an off. With damage

Had thrown yaw rate sensor code.

Took it back out, did a few laps up to 7/10ths, was fine for a few laps, then vac light came on again and brakes went slightly nuts again, but fortunately no off.

Thinking about disconnecting ABS to prevent but looking for ideas...

WTF...

Is this a stock brake system? Calipers, rotors, master cylinder? Did the sensor failure correspond to the locked wheel? Seems like a scary failure regardless. Really bad for a stock setup.

Sent from my SM-G955U1 using Tapatalk

ZDan · 09-14-2020, 04:18 PM

Same thing with 5 second hold or pedal dance.

Just disconnected both ABS fuses. Kinda think this should work...

ZDan · 09-14-2020, 06:10 PM

Stock PP brakes with CSG Spec C2 pads in front, Winmax W5 in back. Setup had zero issues at Palmer. Practicing on Conti ECS tires today's so way undertired but again no probs at Palmer.

Tried pulling both ABS fuses but every light on dash lit up including Check Engine, revs limited to 4000ish. Re-installed small 25A ABS fuse and cleared CEL, ran some laps. No ABS so I could lock fronts, but controllable now, whereas before one front (usually left) would lock first and car would pull hard to right or STRONGLY hunt left/right.

CSG Mike · 09-14-2020, 07:09 PM

Try putting ABS fuses back on, but deleting (removing) a wheel speed sensor. You'll not have ABS, but the car should drive mechanically.

rice_classic · 09-14-2020, 07:10 PM

Since the yaw sensor is built into the ABS block, it could be a sensor that is failing causing that weird braking event and pulling one of the fuses would explain why the cars works more as intended when the ABS block is disabled.

Could also be a dirty or failing wheel speed sensor as well.

rice_classic · 09-14-2020, 07:11 PM

Quote:

Originally Posted by ZDan

Stock PP brakes with CSG Spec C2 pads in front, Winmax W5 in back. Setup had zero issues at Palmer. Practicing on Conti ECS tires today's so way undertired but again no probs at Palmer.

This might be your problem - your car misses the Hoosiers and is complaining.

redlined600 · 09-15-2020, 09:36 AM

Does your reader show chassis codes as well? Any of those pop up?

ZDan · 09-15-2020, 12:49 PM

Normal readers didn't give any info. Guy here with laptop and Toyota software did deeper dive to find yaw sensor error.

Running fine today with big 40A ABS fuse pulled. ABS light on of course, also VSC malfunction light. Weirdly the red "BRAKE" light also on as if parking brake set, but car running great today. Do 4 laps in 14s, best lap 2:14.32, better than I expected before the event! Tires seem to need a few warm-up laps tho, 1st 4 laps were slower which doesn't bode well for great time trial (3 laps), but just glad to be runnin decent laps!

ZDan · 09-15-2020, 01:16 PM

Quote:

Originally Posted by CSG Mike

Try putting ABS fuses back on, but deleting (removing) a wheel speed sensor. You'll not have ABS, but the car should drive mechanically.

Didn't get a chance to try pulling a sensor, but seems to be working fine with 40A ABS fuse pulled...

ZDan · 09-15-2020, 05:32 PM

2:14.002 in the time trial!

rice_classic · 09-15-2020, 08:23 PM

Quote:

Originally Posted by ZDan

2:14.002 in the time trial!

I'm operating under the assumption that the ABS block is also responsible for brake bias. By pulling the big fuse, did you notice your front:rear bias to be any different? Easier to lock up one end vs the other than before?

timurrrr · 09-16-2020, 03:43 AM

Quote:

Originally Posted by ZDan

Normal readers didn't give any info. Guy here with laptop and Toyota software did deeper dive to find yaw sensor error.

Do you have any data acquisition system?
Can you log what you're getting from CAN PID 0xD0?
https://github.com/timurrrr/RaceChro...86.md#pid-0xd0

09-14-2020, 03:08 PM	#1
ZDan Senior Member Join Date: May 2011 Drives: '23 BRZ Location: Providence, RI Posts: 4,584 Thanks: 1,376 Thanked 3,890 Times in 2,032 Posts Mentioned: 85 Post(s) Tagged: 0 Thread(s)	Yaw sensor and braking trouble at track Weird day at the Glen... Got a VSC light at track. Then massive left front lockup going into 6. Had an off. With damage Had thrown yaw rate sensor code. Took it back out, did a few laps up to 7/10ths, was fine for a few laps, then vac light came on again and brakes went slightly nuts again, but fortunately no off. Thinking about disconnecting ABS to prevent but looking for ideas... WTF...

09-14-2020, 07:10 PM	#7
rice_classic Senior Member Join Date: Jun 2012 Drives: Nevermorange FRS Location: Seattle, WA Posts: 4,160 Thanks: 755 Thanked 4,200 Times in 1,803 Posts Mentioned: 77 Post(s) Tagged: 1 Thread(s)	Since the yaw sensor is built into the ABS block, it could be a sensor that is failing causing that weird braking event and pulling one of the fuses would explain why the cars works more as intended when the ABS block is disabled. Could also be a dirty or failing wheel speed sensor as well. __________________ SCCA T4 - FRS

09-15-2020, 09:36 AM	#9
redlined600 Senior Member Join Date: Nov 2014 Drives: Fr-s Location: MN Posts: 733 Thanks: 125 Thanked 492 Times in 266 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	Does your reader show chassis codes as well? Any of those pop up? __________________ Build log

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09-14-2020, 04:18 PM	#4
ZDan Senior Member Join Date: May 2011 Drives: '23 BRZ Location: Providence, RI Posts: 4,584 Thanks: 1,376 Thanked 3,890 Times in 2,032 Posts Mentioned: 85 Post(s) Tagged: 0 Thread(s)	Same thing with 5 second hold or pedal dance. Just disconnected both ABS fuses. Kinda think this should work...

09-14-2020, 06:10 PM	#5
ZDan Senior Member Join Date: May 2011 Drives: '23 BRZ Location: Providence, RI Posts: 4,584 Thanks: 1,376 Thanked 3,890 Times in 2,032 Posts Mentioned: 85 Post(s) Tagged: 0 Thread(s)	Stock PP brakes with CSG Spec C2 pads in front, Winmax W5 in back. Setup had zero issues at Palmer. Practicing on Conti ECS tires today's so way undertired but again no probs at Palmer. Tried pulling both ABS fuses but every light on dash lit up including Check Engine, revs limited to 4000ish. Re-installed small 25A ABS fuse and cleared CEL, ran some laps. No ABS so I could lock fronts, but controllable now, whereas before one front (usually left) would lock first and car would pull hard to right or STRONGLY hunt left/right.

09-14-2020, 07:09 PM	#6
CSG Mike Join Date: Jul 2012 Drives: S2000 CR Location: Orange County Posts: 14,529 Thanks: 8,918 Thanked 14,175 Times in 6,834 Posts Mentioned: 966 Post(s) Tagged: 14 Thread(s)	Try putting ABS fuses back on, but deleting (removing) a wheel speed sensor. You'll not have ABS, but the car should drive mechanically.

09-15-2020, 12:49 PM	#10
ZDan Senior Member Join Date: May 2011 Drives: '23 BRZ Location: Providence, RI Posts: 4,584 Thanks: 1,376 Thanked 3,890 Times in 2,032 Posts Mentioned: 85 Post(s) Tagged: 0 Thread(s)	Normal readers didn't give any info. Guy here with laptop and Toyota software did deeper dive to find yaw sensor error. Running fine today with big 40A ABS fuse pulled. ABS light on of course, also VSC malfunction light. Weirdly the red "BRAKE" light also on as if parking brake set, but car running great today. Do 4 laps in 14s, best lap 2:14.32, better than I expected before the event! Tires seem to need a few warm-up laps tho, 1st 4 laps were slower which doesn't bode well for great time trial (3 laps), but just glad to be runnin decent laps!

09-15-2020, 05:32 PM	#12
ZDan Senior Member Join Date: May 2011 Drives: '23 BRZ Location: Providence, RI Posts: 4,584 Thanks: 1,376 Thanked 3,890 Times in 2,032 Posts Mentioned: 85 Post(s) Tagged: 0 Thread(s)	2:14.002 in the time trial!

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