I replaced the stock speedo with a HD speedo/tach combo on a 07 Softail. It’s a plug and play setup. It worked great for about 150 miles but now the tach won’t settle below 3000 RPM even when the engine is off. So 3000 RPM is the new 0 and idle is up around 4000.

The parts guy says the unit needs to be ‘flashed’ to the bike. The instructions, service manual, and electrical manual say nothing about this.

Has anyone seen this happen and know how to zero it or do you think it’s just a defective unit?

 

I had the same problem with the speedo/tacho from HD but it was happening with the speedo. The dealer said they'd been having a lot of problems with the combined units andreplaced it 3 times, in the end I gave up and put a bar mounted Tacho on.

 

Thanks. I discovered yesterday (by accident) that if you cut power by popping out the maxi-fuse. It re-zeros the speedo and tack. So far the tach seems to be working normally. We'll see if it lasts. This make me wonder if the problem isn't in the ECM.

Steve