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I've seen speed sensors contact tone wheels when the structure was dynamically loaded. It doesn't take much contact, barely making scratches on the sensor if at all. With the low surface speeds involved and small tone wheel tooth spacing, the sensor most likely has a very small design clearance, like a few thousands. From the appearance of the crud on the end of the sensor, the clearance is in the area of 10 thou., with no sign of contact. To measure clearance, place a little bit of modelers clay or similar on the end of the sensor, bolt down the sensor without moving the tone wheel, remove sensor and see how thin the tooth marks are in the clay. To detect contact, a thin coat of dark color lacquer or bluing on the end of the sensor will show if things are contacting in sweepers. If contact is an issue, the sensor could be spaced out with a washer shaped shim under the mounting boss. A good place to start maybe something like 5 thou thick, like a piece of tin can.
I was concerned about the tone wheel being loose also. Poked around a bit trying to get it to move and concluded that it was not likely with time and a bit of rust to help hold it. Our ABS light and action is at low speeds which indicate contact, or loss of signal from a large gap, or wiring issues. At moderate and higher speeds the signal will be more substantial, with ABS issues are more likely caused by sensor contact. Can you feel any play in the wheel bearings?
Talking about contacts, the wiring connectors should be exercised to help assure good electrical contact. Looking over the control connector contacts and finding and checking the sensor connections maybe a good idea. Wonder if the control has internal solder contact issues like door locks modules and relays? Happy hunting..
posted by 70.58.213...
, Mon, 17 Oct 2011 04:21:17
, Tue, 18 Oct 2011 05:41:47
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