My son picked up a nice 1999 FXDS. It has a problem with the speedometer. I have searched the forum, but haven't found an answer yet.

The speedometer comes on, I start the bike, all is well for a few seconds, then the engine light comes on in the speedo, the odometer reading goes out.

Here's what we have done so far: 1- cleaned the speedometer sensor. It had metal debris on the magnet. No help, problem remains. 2- Checked the battery, it is good, 12.7 volts. 3- checked the charging system at the battery and found some interesting results.

When first started the charge is in the 12V range, the speedometer is working fine, watched the charge on the meeter while the bike was running, and the voltage increased to 18.6V. When the charge voltage goes over 15 volts, the speedometer stops displaying the odometer, and the engine light on the speedo comes on again.

Is it possible the voltage regulator is bad, causing the speedometer to fail?

Any and all ideas appreciated. I don't want to troubleshoot by throwing parts at the problem.

 

Just an FYI......... it was the voltage regulator. Bought a new one, installed it, problem solved.

 

Yes - when the voltage exceeds 15, the speedo's usually stop working. That is a very common symptom when voltage regulators poop the bed.