1999 Speedometer Problems

[fatboyjrk]

Hello,
My uncle is having some issues with the speedometer on his 1999 Fatboy. Here's what I know.
While driving down the road sometimes the needle will get stuck, sometimes it will go to zero. Whenever either of these two things happen the odometer display goes away. It can stay this way for many miles. Normally happens when the bike is cold. We were doing some trouble shooting in the garage today and found that we could make the odometer blank out occasionally while revving the engine. This would happen whether we had the speed sensor plugged in or not. When the key is on and nothing is running there is approximately 13 volts at the orange wire and 11 at the green wire. I noticed that the odometer will blank out while the engine is cranking over to start (don't know if this is normal) and the green wire will drop to 8 volts. I don't notice this voltage drop when the odometer is blanking out while revving, but I may have missed it. The speed sensor is new. The bike has 12000 miles. He just purchased and installed a speedometer from a 2003 softail with 400 miles off of ebay and has the same issue. Any help would be greatly appreciated.
Jason

 

[glider]

Sounds like you are loosing continuity in the circuit. With a different speedo and speed sensor, you have replaced the more common problems found in these systems. Open the plugs in this system as well as the one at the back of the speedo under the console and check for corrosion or a poor connection , apply some dielectric grease to them as you go and you may locate the problem. It;s just a matter of going through the system from one end to the other to find out where you are loosing the signal.

 

[fatboyjrk]

Thank you for the reply. Is it normal for the odometer to go out during cranking? Am I correct in assuming that the orange wire supplies back lighting while the green is for the speedo/odo? Why does Harley split them up? Is there a regulator for this green wire that could be faulty? Could I feed both pins from the orange wire? I know the orange wire gets up to around 16 volts when your really cranking on it. I don't want to fry anything.
Thanks again,
Jason

 

[glider]

Check your cranking voltage. If it's too low that could be why you are loosing the odometer. 16V is excessive.

As far as the wiring colors, There's diagrams in the back of the factory manual, I don't have one for that bike.

 

[fatboyjrk]

Okay. I'll start tracing. I didn't not talk too good in the last post. When turning the engine over with starter voltage at green/white is low. When revving the engine to high rpms voltage on the orange/white is high. Thanks again for your help.