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The tach and speedo were working intermittently until I was on the interstate cruising about 65 and sped up to about 85. Got up to about 80 or so and both the speedometer and tach needles did a swoop to the right and then stopped working all together. No lights or anything. The only thing these two components have in common is a ground that I'm aware of so I assumed this is the problem. There's no continuity between the harness side (under the seat) of the tach and the ground stud. This leads me to believe there is a broken wire but I can't find it. The wiring harnesses look fine and unmolested.
Any suggestions other then removing the entire wiring harness? Is it feasible to run separate grounds? Or, is this a common fault with a simple solution?
I'm not sure exactly what you have, but you might have another ground (if it's working) in position #11 in connector 20B that you could tap into if a bad ground (position #12) is your problem.
I'm not sure exactly what you have, but you might have another ground (if it's working) in position #11 in connector 20B that you could tap into if a bad ground (position #12) is your problem.
I really appreciate the diagram. I now realize I misspoke in my OP. The continuity check I did was actually on the speedometer side and not the tach and it was Pin C on the 65a connector (no continuity to ground). There was continuity between pin 12 on 20a and ground. By looking at the diagram, the ground from the speed sensor to the speedometer is its own circuit and has nothing to do with the other ground circuit that connects to the tach. Or does it? Could the speed sensor be the culprit? I'll take a closer look at it anyway...
I don't think that the speed sensor would have any effect on the tach.
FYI …. a good place to get wiring diagrams is the HD Service Info Portal https://serviceinfo.harley-davidson....cle/lookupForm
I think you can enter your VIN and it will give you a link to the wiring diagrams. One of the nice things about the site, is that it usually allows you to zoom in/enlarge portions of the diagrams so the old eyes like mine can read them.
Here's a link to the "Wiring Diagrams & Electrical Troubleshooting Guide - 1997 All Models" that can be found by doing a search for "1997 wiring" from the home page. https://serviceinfo.harley-davidson....%3D1997+wiring
Problem fixed! It ended up being a bad pin (12) in the 20B connector (behind the headlight). It wasn't seating correctly within the connector so I removed it, cut it off, added another one, and now is all good.
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97 Dyna Speedo and Tach not working
