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Discussion Starter #1
Hi all.
So i recently built a 954rr that i got last winter for $600 for the track. I rebuilt the motor to OEM spec and i must say, it runs amazing, i cleaned up everything, new crank rods, pistons, everything! Having a fresh motor is nice i must say.

Now that everything is back together i am stumped on this one where the tach is not working anymore. I am trying to figure out where the tach signal comes from. I know the yellow and green wire feeds the tach from the ECU so the ECU sends the signal to the tach. But what sends engine speed to the ECU that i can double check. I checked signal all the way back through the wire and im getting 0V but everything else works fiine.

Keep in mind this is my 2nd 954 so ive been swapping parts to make sure everything is working good. Tach works ECU works but I am not getting any thing to the ECU. Any help will be greatly appreciated
 

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Discussion Starter #4
Yep that is the first thing that I tried. I get 0V on two separate ECM's from both my bikes so i think I am not getting something IN on the ECM
 

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Discussion Starter #6
yep bought a brand new one 0 miles from honda. Everything works except the tach. I don't have a FI light trouble code which is weird if something was unplugged
 

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Maybe take a look at the black harness connector into the ECU could be a loose pin coming from spark wires to ECU , not reading the pulse
 

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Haven't looked in the manual so just spitballing, but the signal comes from the trigger coils in the ignition right? Since you had the engine out I would verify that it is hooked up correctly.
 

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Discussion Starter #9
I'm going through everything and I still can't figure it out I'm going to go through every connector once over because I really wanna get it on the track
 

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The signal should go from the ignition rotor pick up (aka pulse generator) on the right side of the crank to the cam pulse generator, then to the ECU, then from the ECU through the harness to the tach on the yellow green. If all of those components are good, and there are no splits/burns/shorts, its probably an ECU issue.

I'm speaking in general terms here, so if someone has more specific knowledge, I won't be offended.
 
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