Motorcycle Repair: 1999 FXD Dyna Superglide speedometer, fxd dyna, speedo needle

Question
Hello,

I have a 1999 FXD Dyna Superglide with 28,700 miles and it usually runs great.

The other day on the x-way my speedo/odometer stopped working and the engine light came on.  The back light stayed on.  Up on the surface street the speedo would work in unison with the turn signal, but I lost the turn signal timer.

At home I put the speedo into diagnostic mode and got a D02, D06, D08, and D10 error codes.  I started troubleshooting by following the flow chart for those codes in the service manual.  It was telling me to get a new speedo.  The service desk guy at a dealer near me said it was dollars to donuts that it was the sensor.  So I bought one and tried it.  It didn't help.

At this point the speedo would work at idle, but would blink out when I revved the engine.  So I cleaned my old sensor and re-installed.  Then I cleared all the codes in the speedo and started again.  This time the only code I was getting was "D08 Speedometer power overvoltage (White/Green)."  The flow chart said to check for voltage fluctuation while wiggling the harness.  I did this with the key on, but the engine not running.   No fluctuation.  Then I started the engine.  I got 13V at idle, but when I revved it, it went to 18V.

Was I checking this right?  What is an acceptable range on voltage?  Will I fry a new speedo at this voltage?

I don't think I'm setting any engine codes.  At idle, the speedo needle goes to zero, the odometer is on, and the engine light is off.  When I rev it, the needle drops, the odometer goes blank, and the engine light goes on.  I've set an engine code before and you can really tell when you start the bike.  The light stays on a long time, 10 or 12 seconds.  Its not doing that this time.

Sorry for the long winded question.  Any help would be greatly appreciated.  Thanks.

Julian

Answer
If you are getting 18 volts that is to much. The stator should be only putting out around 13.5 to 14 volts. Before changing the speedo I would check the voltage regulator and stator. That might be where your problem lies.
Good luck and happy riding
Mike