General "memory" (basic setting or coding lost) Question

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stefdds

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When you remove the instrument cluster, often the basic settings in the ABS system are lost.


I've read several threads where as Bruce commented here that when ever a Instrument cluster or (I think) a ABS unit is physically disconnected the coding or, in this case, the basic settings are lost for one or both units ; why is that? Many times the power / battery is disconnected from the system for long periods of time and this coding lost condition or loss of basic settings does not occur. Is that loss by design ?
 
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Uwe

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Yes, I believe the loss is by design. However, it's not a problem when the battery is disconnected.

It's only a problem if the car (and thus the ABS module) is powered up while the instrument cluster is missing, or while a "foreign" instrument cluster is in place. In either case, the programming in the ABS module will then assume it is no longer in the car it belongs in, and will then wipe its coding and/or basic settings.

-Uwe-
 
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stefdds

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OK, thanks Uwe. (and happy Saturday btw)

I understand now, especially with the instrument cluster (mileage record).

Does the same scenario as above occur if the ABS module (ie. pump with brake lines running to it - under the hood) is changed with a donor unit ? (I think I have read those threads, but just want to verify) If it does (ie ABS gets wiped), thus it is necessary to have the AScan and Basic settings of the original ABS module saved/copied as it will need to be coded or adapted (?).


Also, how about if the original ABS module was removed for say access to other repairs (battery power disconnected) and then once repairs are finished the same ABS module is reinstalled. Any "wipe" problems in that situation?
 
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Uwe

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Does the same scenario as above occur if the ABS module (ie. pump with brake lines running to it - under the hood) is changed with a donor unit ?
Depends. If the control module is replaced, yes. If just the hydraulic/mechanical bits are replaced, it might lose Basic Settings, but it shouldn't lose Coding.

Also, how about if the original ABS module was removed for say access to other repairs (battery power disconnected) and then once repairs are finished the same ABS module is reinstalled. Any "wipe" problems in that situation?
In principle, there shouldn't be.

-Uwe-
 
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