Tachometer needle jumping (HELP!!)
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Cruiser
Joined: Jun 2008
Posts: 139
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From: USA
Tachometer needle jumping (HELP!!)
I purchased a used HD tachometer from a friend of mine. I had to make my own wiring harness and I hooked up the ground and the light/power wire. I coiled up the trigger wire at the ECM and had the dealer make that connection to the #3 terminal at the ECM. The tach seemed to work ok but I never really rolled it on since I had it hooked up. Today I started to put it thru the gears and opened it up. As soon as the tach reached approx 3500 rpm the needle started jumping + - 1000 rpm's. If I were to throttle up at about 1/2 throttle the needle is fairly smooth thru that same range. Also when stopped and revving the motor it seems fine also. I checked all the connections and they seem tight and OK. The only thing that comes to mind now is possibly a bad tach or could it be RF getting into the trigger wire under hard 100% throttle and load. I did use a solid (no strand) wire for the trigger wire. I don't know if I should have used stranded wire for that. Does anyone have any thoughts?? This is on an 07 fxstb. Again normal riding seems to be perfect on the tach.
I posted this on another site because I need ALL the input I can get.
(I am told it could be the solid wire, and I am leaning in that direction)
Thanks in advance.
__________________
I posted this on another site because I need ALL the input I can get.
(I am told it could be the solid wire, and I am leaning in that direction)
Thanks in advance.
__________________
Road Master
Joined: Mar 2007
Posts: 1,177
Likes: 23
Crank Position Sensor may be loosing sync. Do you know anyone that owns a SERT?
If the SERT tach signal is solid then it most likely is vibration and wiring issues internal of external of the tach.
If the SERT tach signal is solid then it most likely is vibration and wiring issues internal of external of the tach.
Last edited by whittlebeast; Aug 20, 2008 at 07:37 AM.
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Cruiser
Joined: Jun 2008
Posts: 139
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From: USA
tach needle still jumping, thought it was fixed.
I thought it was fixed but it is doing it again. Same thing. Ckecked all the areas that I could. I turned the ign. to on (motor not running) and tapped the tach housing quite hard with my hand and the needle did jump 600 rpm or so. Turned the ign. off and did the same thing (tapping on the tach) and no jumping. Bad tach??? Seems like an internal problem to me but what do I know. The dealer said he could not get the tach to work at the speedo connection when he tried to hook up the signal wire for me. (that's where the instructions for a 07 fxstb say it should go) They did get it to function when they hooked it to the #3 terminal on the ecm. Any thoughts?? Bad tach?? What is the correct part number for a 2007 FXSTB night train. (mini tach 2 5/8" black face no shift light)
Thanks guys.
Thanks guys.
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broken, connection, fuel, harley, hd, hooking, jumping, jumps, jumpy, needle, rpm, stopped, tach, tachometer, tachometers
