Whats the tolerance on the ABS sensor?
07-08-2013, 05:48 AM
#4
Not sure I understand what you are saying...even if you change the gear you still have the same size tire... My question is I have a 27.7" rear tire and a 25.5 front. I am obviously over the max by the lights on the dash. How close do I need to be to get the ABS working correctly? 1", .75"?
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07-08-2013, 09:36 PM
#9
from the way i understand it, the ABS sensor reads how many rotations your tire makes and and compares it to the others, under braking if there is a difference bigger then X in tires speeds then the abs activates. if the tire speeds have a difference bigger then X (x = max tolerance of sensor from front to rear) while not under braking, the ABS disables itself if this continues for a certain amount of time, like on a dyno.
Now i am no expert, but when GM explained it to me, this is how i understood it. i believe what he is asking is what is the max tolerance that you can have between the tire sizes and the ABS still work and not fault out.
Now i am no expert, but when GM explained it to me, this is how i understood it. i believe what he is asking is what is the max tolerance that you can have between the tire sizes and the ABS still work and not fault out.
07-09-2013, 03:57 AM
#11
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You clearly don't have an understanding of how the ABS system works. The speedo is run by a sensor in the transmission tail. It estimates speed based on transmission output shaft rotations. That's with fixed info of everything BEHIND it, like gear ratio and tire size. Change one of those and your computer's calculation will be wrong. A tune will fix this. None of that matters to your BCM (body control module) and ABS computer (underhood). The ABS system measures tire rotations only. All 4 tires must spin the same speed or within a certain percentage of each other. If one or more are too far different from the rest it will render the system inoperable. It cannot properly calculate tire spin for TCS and tire lock-up for ABS with sensors reading incorrectly. This is hard coded into the ABS computer and cannot be changed. If you run 28s on the rear and 26s on the front, your ABS/TCS will not work, period.
07-09-2013, 04:35 AM
#12
You clearly don't have an understanding of how the ABS system works. The speedo is run by a sensor in the transmission tail. It estimates speed based on transmission output shaft rotations. That's with fixed info of everything BEHIND it, like gear ratio and tire size. Change one of those and your computer's calculation will be wrong. A tune will fix this. None of that matters to your BCM (body control module) and ABS computer (underhood). The ABS system measures tire rotations only. All 4 tires must spin the same speed or within a certain percentage of each other. If one or more are too far different from the rest it will render the system inoperable. It cannot properly calculate tire spin for TCS and tire lock-up for ABS with sensors reading incorrectly. This is hard coded into the ABS computer and cannot be changed. If you run 28s on the rear and 26s on the front, your ABS/TCS will not work, period.