Last night I installed a new Dakota Digital on my 17 SB, which has about 625 miles on it. I took it for a short ride and then remembered I needed to look at the stock odo to get the exact mile and set the DG odo. So I put the stock odo back on, and holly ***** it now shows 12,725 miles??

What happened here?

 

I'm pretty sure there is a Syncing process that must be adhered to in order to get the Speedo's to sync up. I know that on both my Fat Boy, and my Road King, I had to sync the speedo's to maintain the original and proper mileage. Was that what you did?

 

Speedo is not the issue.

I bought the bike new. Rode it about 600 miles. Last night removed the gauge and put on a new DG unit. Took a 2 mile ride, put the stock gauge back on. Mileage now shows 12,725.

 

Yeah, it sounds like the Speedo is EXACTLY the issue.
Like I said, there is a process when swapping speedometers that involves a cable and a link up with the bike with the new Speedo. You have to tell the new Speedo what the old Speedo had, in order for them to sync. Otherwise the new speedo uses some random figure as it's base.

 

I am not sure if you understand what I am saying or I am not understanding you.

The new speedo ( Dakota Digital) I already set to 625. But before I did that, I put the original speedo back on to see the exact mileage, and it showed 12725.

So, after disconnecting the original gauge and then putting it back on 24 hrs later, the mileage went from around 600 to over 12000.

 

What we have here is, failure to communicate.

 

The anti-tampering gremlin in your original speedo was let loose.

 

I know that with the Harley branded replacement speedos there is a synchronizing process. This is so you can temporarily switch out a speedo unit to test for malfunctions. The Harley ECU keeps track of the mileage, and transfers that data after a certain number of miles. Your Dakota unit may be different, but the newer Harley electronic brains definitely track the bikes true mileage. Best of Luck.

 

Did you leave it parked in a strange parking lot? Like in Ferris Bueller? You know those parking lot attendants put on extra miles.
Or you might have had a surge.

 

For future reference, maybe it will help someone else down the road.

On newer bikes, ECM will "marry up" only. Meaning if you connect a speedo that has higher than what is on the ECM, it will take that mileage. If it's lower, it remains on what ECM has. ( talking about after market speedos, if its another Harley speedo and already married to another bike you will probably get a Err code)

So, when I put the Dakota unit on, which had 12xxx miles, the ECM took it and showed that mileage. When I put the stock Speedo back on it still showed the 12xxx.

The 31 mile rule, which means after that the ECM is married to the new speedo, has nothing to do with it, neither has "Syncing".

The only way to fix this is to get an approval from HD Corporate. Then have the dealer send your ECM and stock Speedo to HD tech center and have them fix the mileage. Dealer wont be able to touch the miles.

To prevent this, make sure your Dakota unit is not used, or if it's used sent it to DD to have them reset to zero or to the miles that you want it to be on.

This is apparently to deter people from tampering with their odo readings. But Why not have the ECM hold on to the original no matter what?