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Old 12-24-2012, 12:17 AM
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bluebee bluebee is offline
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Location: San Jose, California
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Mein Auto: 02 BMW 525i M54 auto 130K
Originally Posted by geobrick View Post
Has anyone else had the trifecta return within months of a successful repair?
Not many. Most of the repairs seem to work (whether they be the 'rebuilt' module or the brand new modules). The rebuilders generally give a decent warranty; not sure about the new modules (I'm not a big believer in warranties - but if you have one - make use of it).

Originally Posted by geobrick View Post
Wouldn't the car need to be moving before it knew a sensor wasn't reporting wheel speed?
Dunno. I could imagine, say, a shorted wheel speed sensor (or an open, or anything in between) delivering the wrong signal input to the initial test routine of the ABS control module - even without the vehicle moving.

The wheel speed sensors and the ABS control module are the two fragile components of the ABS system, but, as you know, there are over 20 sensor inputs to the system which can go bad.

Most of the time though, it's either the wheel speed sensor (rarely, if ever more than one at a time), or the module itself.

Details in post #48 of this thread:
- E39 trifecta diagnostic DIY
Please read the suggested threads and add value, either by pictures or by descriptions, so the next person stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need
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