Count me in this crowd...
Called them, they were..., to put it nicely, not friendly ("you must be an idiot who can't install it right.") The guy carried on for minutes about how no one follows instructions (I did to a "T" except I soldered the ground wire for power to the harness ground wire that mounted at the coil and runs directly to battery negative), seemed miffed that I mentioned that I tried all the solutions people had online who had the same problem (like, "You're the first person I've heard of with a high reading and jumpy tach!").
Apparently, ground isn't ground (even hard soldered to a wire directly grounded to battery - through a soldered loop term) for Trailtech.
So after running a new harness and integrating this into it, I cut both power and ground, soldered new wires to both, then ran both to battery poss and neg, totally dedicated wires directly to batt. Same thing. 6k RPM showing for idle. And a bit jumpy.
For the sensor wire, tried everything from two to 6-8 wraps. Same.
Ran sensor wire away from any other wires or conductors, using zip ties to hold it away just to test if it might be picking up noise from anything else. Same.
At this point, and given the attitude at Trail Tech (Gosh..., speaking of tech, was one for mil-spec builds and repairs for a decade before another decade as an engineer - including a diesel cycle redesign in India, but..., I must be a dunce since I can't get a tach to work..., of course), they're getting this whole thing back.
Bottom line, I've mounted probably a dozen or more tachs and never had this issue. Because they can't seem to figure out how to coil out noise in their design or whatever it is, anyone with a problem with it is to blame.
The time spent trying to correct this is equal to three times the cost of this unit at this point. Time to stop, dissect the whole thing out, pack it up and return it, with a, "no more Trail Tech motto."
I'll run something else, but not paying for their product that's this hit and miss with people. And certainly not for someone to waste my time and act like they did on the phone.
Edited by TomJ2, April 20, 2016 - 03:02 PM.