Left vs. Right Rear ABS Sensors?

JHZR2 · 06-14-2018, 10:12 PM

Hello,

Im from over at the 1addicts board, but it seems in doing google and other searching, that the bulk of the knowledge exists in here. This is about my 2011 135i convertible (21k miles), which is, to my understanding, very similar to the E90 cars in many components.

What Id really love is an explanation of how the ABS/DSC system works with respect to the right vs. left rear sensors. If Im not mistaken, each is used for a different function. But how does one affect the other when one fails? Does anyone have a good grasp of the "extrapolation" errors, versus indications of an electrical fault, poor sensing quality, or something else?

Long story short, a month ago I got 32D3, 5DB1 and 5DB3 codes, which meant rear left sensor extrapolation and starting voltage readings. Replaced the sensor with a new ATE unit, and all errors went away. Didnt drive the car much due to rain (its a convertible), but today drove it about 40 miles. At the end of the day, lights come back.

This time its 32D6, 5DB1, 5DB3 and 5DC3, so now there's a pointer to the rear right sensor for both the 32D6 code and the 5DC3 code.

Ive learned from on here that the ABS sensors are flaky parts. That's fine, the rears are easy enough to replace. But why would the rear left errors re-emerge???? I mean, I know I put a new, good sensor in there, I know it caused the codes clear. And if it was just that both had a mortality around the same time, why would a new failure of the right cause a renewed failure of the left??

Thanks for any insight that you can provide!

ptpending · 06-15-2018, 01:06 AM

if you said about rains - you need to check if DSC module not flooded with water
this can be if drains under hood clogged with old leafs
the module is located under left cover near windshield
if you can do circuit tests you also can check circuit from module to sensor
there also such design flaw in left rear arch that wire loom (including DSC sensor and headlight level switch) rubs on the edge and breaks
you'll need to remove wheel and wheel arch cover to check this

JHZR2 · 06-15-2018, 06:02 PM

Thanks for this guidance. It's strange. I cleared codes, drove 20 miles today, and no return.

Drains were clear. No sign of stanfong water by DSC.

I have to really truly wonder if they both started to fail within a few hundred miles of one another.

cronus · 06-15-2018, 10:12 PM

Mine failed within a week of each other. Left one went first. The speedometer stopped working when the right one failed. My Indy said it's pretty common for multiple ones to fail within a short time period.

JHZR2 · 06-15-2018, 10:26 PM

Quote:

Originally Posted by cronus

Mine failed within a week of each other. Left one went first. The speedometer stopped working when the right one failed. My Indy said it's pretty common for multiple ones to fail within a short time period.

Interesting, thanks! After replacement did any issues come back with the sensors?

My speedometer has never stopped working other than a minor blip when the lights came on. I think the left does speedometer, the right does cruise control. I haven't checked cruise functionality.

Clearing the codes for engine and brakes worked for now and no codes have returned (yet). Buying the sensor to be prepared regardless. I guess the question is if I buy one or three and just bite the bullet.

Thanks!

lookalikehuuh · 06-16-2018, 01:54 AM

i had some similar issues a year or two ago... we fixed the issue by replacing the wheel bearing since apparently the sending unit inside had broken somehow and was causing all kinds of weird issues. Cost me tons of money in parts and a ton of time to figure that one out.

cronus · 06-17-2018, 11:14 PM

Quote:

Originally Posted by JHZR2

Interesting, thanks! After replacement did any issues come back with the sensors?

My speedometer has never stopped working other than a minor blip when the lights came on. I think the left does speedometer, the right does cruise control. I haven't checked cruise functionality.

Clearing the codes for engine and brakes worked for now and no codes have returned (yet). Buying the sensor to be prepared regardless. I guess the question is if I buy one or three and just bite the bullet.

Thanks!

No issues after replacing both sensors. I was really surprised that a failed speed sensor could affect the speedo.

ptpending · 06-18-2018, 12:41 AM

Quote:

Originally Posted by cronus

No issues after replacing both sensors. I was really surprised that a failed speed sensor could affect the speedo.

that's ok, one of the rear dsc sensors is used as speed source for speedo

ptpending · 06-18-2018, 12:43 AM

Quote:

Originally Posted by lookalikehuuh

i had some similar issues a year or two ago... we fixed the issue by replacing the wheel bearing since apparently the sending unit inside had broken somehow and was causing all kinds of weird issues. Cost me tons of money in parts and a ton of time to figure that one out.

thats is well know problem but you have to get into few potholes before

EnintyToo · 06-24-2018, 03:02 PM

My car kept losing the left rear speed sensor. Turned out to be the pulse ring on the half shaft rusted so bad it was scratching the face of the sensor, opening it up and moisture caused it to fail. I just put a small 1MM washer under the sensor body at the mounting screw tab.

06-14-2018, 10:12 PM	#1
JHZR2 Major 74 Rep 1,001 Posts Drives: 91 E30, 11 135i cv Join Date: Mar 2009 Location: New Jersey iTrader: (0)	Left vs. Right Rear ABS Sensors? Hello, Im from over at the 1addicts board, but it seems in doing google and other searching, that the bulk of the knowledge exists in here. This is about my 2011 135i convertible (21k miles), which is, to my understanding, very similar to the E90 cars in many components. What Id really love is an explanation of how the ABS/DSC system works with respect to the right vs. left rear sensors. If Im not mistaken, each is used for a different function. But how does one affect the other when one fails? Does anyone have a good grasp of the "extrapolation" errors, versus indications of an electrical fault, poor sensing quality, or something else? Long story short, a month ago I got 32D3, 5DB1 and 5DB3 codes, which meant rear left sensor extrapolation and starting voltage readings. Replaced the sensor with a new ATE unit, and all errors went away. Didnt drive the car much due to rain (its a convertible), but today drove it about 40 miles. At the end of the day, lights come back. This time its 32D6, 5DB1, 5DB3 and 5DC3, so now there's a pointer to the rear right sensor for both the 32D6 code and the 5DC3 code. Ive learned from on here that the ABS sensors are flaky parts. That's fine, the rears are easy enough to replace. But why would the rear left errors re-emerge???? I mean, I know I put a new, good sensor in there, I know it caused the codes clear. And if it was just that both had a mortality around the same time, why would a new failure of the right cause a renewed failure of the left?? Thanks for any insight that you can provide!
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06-15-2018, 01:06 AM	#2
ptpending Colonel 456 Rep 2,749 Posts Drives: e91 Join Date: Dec 2013 Location: Poland iTrader: (1)	if you said about rains - you need to check if DSC module not flooded with water this can be if drains under hood clogged with old leafs the module is located under left cover near windshield if you can do circuit tests you also can check circuit from module to sensor there also such design flaw in left rear arch that wire loom (including DSC sensor and headlight level switch) rubs on the edge and breaks you'll need to remove wheel and wheel arch cover to check this __________________ E81 2007 130i 6cylinder Montego blue Retrofits: Harman Kardon, High-beam assistant, Removable tow hitch. Auto-dim folding exterior mirrors. Lumbar support. Perfomance Brakes.
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06-15-2018, 06:02 PM	#3
JHZR2 Major 74 Rep 1,001 Posts Drives: 91 E30, 11 135i cv Join Date: Mar 2009 Location: New Jersey iTrader: (0)	Thanks for this guidance. It's strange. I cleared codes, drove 20 miles today, and no return. Drains were clear. No sign of stanfong water by DSC. I have to really truly wonder if they both started to fail within a few hundred miles of one another.
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06-15-2018, 10:12 PM	#4
cronus 3 pedals 5 Rep 114 Posts Drives: 09 E90 335i Join Date: May 2009 Location: New Orleans iTrader: (0)	Mine failed within a week of each other. Left one went first. The speedometer stopped working when the right one failed. My Indy said it's pretty common for multiple ones to fail within a short time period.
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06-16-2018, 01:54 AM	#6
lookalikehuuh Major 700 Rep 1,227 Posts Drives: 2006 330i, 2007 335i Join Date: Sep 2014 Location: San Diego, CA iTrader: (0)	i had some similar issues a year or two ago... we fixed the issue by replacing the wheel bearing since apparently the sending unit inside had broken somehow and was causing all kinds of weird issues. Cost me tons of money in parts and a ton of time to figure that one out.
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06-24-2018, 03:02 PM	#10
EnintyToo Enlisted Member 22 Rep 39 Posts Drives: E90 325 Join Date: Jun 2018 Location: Central East Coast iTrader: (0)	My car kept losing the left rear speed sensor. Turned out to be the pulse ring on the half shaft rusted so bad it was scratching the face of the sensor, opening it up and moisture caused it to fail. I just put a small 1MM washer under the sensor body at the mounting screw tab.
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