Odomoter rolling backward. WTF

[iltl32]

So I JUST bought a used 2005 Monster Dark 620.  The guy told me the odometer wasn't displaying correctly (some of the display LEDs just looked off) because the bike was dropped (damage on cluster gauge confirms that).  Now that I put 100 miles on the bike, it looks like the odometer isn't just 'displaying' wrong, it's clearly showing the wrong numbers.  It rolled from 9870 back down to 9700 miles while I was riding!  My questions:

1. Is the 'true mileage' stored in the ECU or the cluster?  Meaning can I go to a dealer and have them check the true mileage from the ECU, or am I stuck with the mileage on the cluster?
2. Has anybody heard of this before?  Any ideas on fixes?
3. How much could I expect a new cluster to cost me (parts + installation)?  I know it involves the red/black key bullshit.  Ick.

I didn't even finalize the title transfer yet, and I don't know what mileage to list on the paperwork! Any suggestions?

[Nottsbiker]

Have you tried riding everywhere backwards? 

Sorry I'm not more help as my gauges are old skooll mechanical 

[sgollapalle]

I know that the old skool analog ones would turn back, if you turned the wheel backwards.. If they moved the same technology fwd to digital ones, there might be something near the wheel that is counting rotation of the wheel (both fwd and reverse) and the guy might have 'mistakenly' inverted the connections..
I've never looked that closely at how the whole setup works on the digital tacho..

[battlecry]

Did it roll back continuously, or did it change numbers to some that happen to be lower?

[iltl32]

It seems to just jump around.  It will go up for a bit, then drop back down.  And it never seems to correlate with a mile regarding any of the changes.

[motoxmann]

some of the display blocks may not be working. IE: a 7 may actually be a 9, a 5 may actually be a 6, a 1 may be a 7, ect ect

[chris1044]

Having experience in calibration for the auto industry...I find it VERY hard to believe this is actually happening, unless the motorcycle industry really is that far behind vehicles.

As you stated, it's jumping around...that's a problem with the internal circuitry.  Wiring the speed sensor so it read's "backwards" should do nothing (if that's even possible - would need to look at schematics). 

Does the trip meter work?  If so, I wouldn't sweat it...use the trip meter to track fuel mileage/miles to empty, and use the calender/trip meter to roughly gauge the service intervals.

[iltl32]

Yeah, looks like it's the display blocks.  They are totally F'ed.

Does anyone happen to know if they can replace just the displays?  I can't get a whole new gauge cluster because it has the whole immobilizer thing going on.

[Cloner]

Autoecu.com can repair virtually any instrument.  Dash.  Ecu.  Whatever.

I found these folks while searching for a replacement ecu for a '90 906 Paso.  They'll work on pretty much anything electronic.