G'day,
I replaced the speedo on my Heritage in July 2009 with a combination speedo/tacho gauge kit, part no.74746-08. Since then there have been a couple of problems. The latest was when the speedo needle decided to do its own thing. 100k/h down my driveway, 25 k/p along the freeway. Both times it was replaced under warranty. After the last service, when the speedo was replaced, the ABS light comes on and stays on. The service manager says this is because the the unit is looking for the ABS connection where there isn't one.  Short of installing ABS brakes, is there a solution for this ?

in regards to the odd speedo readings Id be thinking the VSS (vehicle speed sensor) may be the culprit? They can get a buildup of contaminants on them which can cause havoc. If the case i think it may give an error code when looking them up  https://www.fuelmotousa.com/p-29661-harley-trouble-codes.html

Do you still have the old speedo to put back in & see if the problem persists with it? While there dab a little dielectric grease on the connection as well