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Hello all, new to the forum, first time Caddy owner, first post.

I've found lots of great info around here but am having one problem I haven't found an exact duplicate of in the forums.

I recently bought a 1988 Seville. When I first start the car the odometer reads "ERROR" but shows the mileage after about a second (approx. 79k). It seems to be counting accurately when compared to the trip odometer. Every now and then while driving "ERROR" will also show but go back to the mileage after a second or so. Could some type of communication problem be causing this error message to show? What connections should I check in order to try and resolve the problem?

When I check the error codes I get BCM error "B556 history." I understand this has to do with the EEprom in the BCM, but am not sure where to go from here.

Thanks in advance. Any help is greatly appreciated.
 

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94 FWB, 93 SDV, 94 FWB (sold), 90 Brougham (sold)
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3,730 Posts
Don't worry about it. Our 90-92 Broughams have the digital dash as well, and we all pretty much have the same symptoms. Nothing to worry about it, it's just 2 bad grounds somewhere that can be fixed for about $150.00

Brian
 

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1995 Sedan Deville Spring Edition
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Well,

this is probably an internal malfunction of the IPC (EEPROM related, probably a checksum error due to a failed write operation or similar such screw-up) and can only be repaired by a GM speedo shop. It is interesting that the mileage does sometimes show up. This seems to indicate that the EEPROM was not entirely corrupted, but rather that the CPU detects some problem with the EEPROM. It will not be a wiring or ground problem outside of the cluster itself, as such a problem would likely cause the whole thing to fail intermittently.

Also you may contact Mr. Whizard, one of the supporting vendors on here - he does digital cluster repair to address this problem. While I have not had occaision to use his services, he has been well regarded by others who have, and they appear to be a very capable outfit - check out their website that is linked from the supporting vendors forum. I know I'd give them a shot if I needed a cluster repair, considering dealer service will run several hundered dollars minimum.

Kdirk
 
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