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ABS brake sensor
My ABS light is on. According to message center, the sensor is bad on axle 2 L. I’m assuming this is drive axle, driver side.
According to my shop manual, the sensor is mounted outboard at the wheel as opposed to the dreaded mounting inside the diff. Anyone changed one and have any hints?
1999 XLV X-6872, liberty #440 -
23 Replies
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Before you change it, see if it has just backed off from the sensor ring. I had mine all pushed in while at JAX and have not had the light since. They said it was common, especially if the wire was too tight and pulled on the sensor at all.
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Exactly what Mark said.
If it doesn’t reset the light after pushing it in it can be checked with an ohmeter before replacing it. If it is mounted outboard it sounds like the Knorr-Bremse calipers, and their shop manual available throught the Prevost publications page gives the resistance value.
They are just held in place with a spring steel sleeve and can back out.
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Joel, I think on a 99 the rear ABS sensor is inside the rear dif housing. If so the 3rd member has to be removed in order to replace.
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We also have an ABS light on which has been traced to drivers side drive axle. Learned the sensor has 95 hits to turn on ABS dash light, ramdomly going on and off.
The sensor is inside the rear end running in oil bath. That itself now turns this repair into big dollars
This means the axles must be pulled then the differential removed from the bus. Sensors are priced at appox $600 each and suggested both be replaced. This appears to be a very poor design with large labor cost to even access the sensors.
Doing some research there is a kit available to mount sensors external but carry’s a high price tag plus additional labor cost.
Has any PC member been through this repair ?
2000 HS-45… 4:56 ratio…. Rockwell third member
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Al, We have the internal sensor and it has been determined that other than triggering the light and the message it has no impact on the functioning of the ABS. I just reset the message board after starting and the warning light has now become a comfortable old friend. Not worth fixing. Geo.
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Geo, open up your PC email I’ll send you my cell number for ABS talk.
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Al, done….I think ???
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The sensors that are on the differential housing are expensive to replace. The differential housing does not have to be removed, but it does have to be opened and the labor is expensive.
The ABS function is inoperative if the ABS light is on, but the brakes work as designed. The only downside to the lack of ABS is in a panic stop situation or on ice or wet surfaces the ABS will prevent wheel lockup and that is very helpful in shortening the stopping distance. Without ABS you are totaly responsible for modulating the brakes to prevent wheel lockup so you cannot just stand on the brakes and let the system modulate braking pressure for you.
If you rear end someone, even though you stopped in the shortest possible distance by skillfully modulating brake pressure as needed, and the other driver’s lawyer or accident investigators read the codes in your ABS and sees long term the ABS has been defective you might have a problem beyond paying for some body work.
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I had used the wrong terminology in my post above. Differential does not need removal.
Access to the rear end is through the differential pulling both axles.
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Put a piece of black type over the light on the dash and have a great trip. That’s what bernie told me how to fix it.
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Me too, ignore it.
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Sounds like the 1999 is inside the diff. Anyone know the chassis cut-off number?
FYI…cut-off date for the change from internal to external sensors is supposed to be mid-1998 production per Prevost parts dept so mine should be external. Thanks for the tip about reseating the sensor in the sleeve. I’ll try that first.
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Not sure they got it right Joel, Al’s is a 2000, 1999 shell and has the internal. Maybe it carried in to the 99 year. Thanks for checking, I was hoping to avoid that nightmare.
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That sensor placement was not one of the smartest choices due to the cost associated with labor to replace a fairly cheap part.
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Got under the bus yesterday. My bus is equipped with drive axle drum brakes and the sensor wire goes through the backing plate and seems to make a right angle turn. Maybe secured against the inside of the backing plate requiring removal of the drum or is this the way the internal sensor is wired?
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