Tachometer not tachometering

[tinman22]

since Occam's razor seems a little dull these days I feel the need to ask yet another question with what is probably an obvious answer.
My tach has not worked since I reassembled Johnny 5 which had suffered an electrical meltdown. Replaced were stator, reg/rec, tci box with a new dyna, new oem harness, 1 coil, v-boost motor and v-boost controller.
Prior to replacing the above parts the bike fired by only on cyl's 2-4 and had no tach. Currently the V-Boost is open and the V-Boost controller is in the truck in Ohio (every box I borrow, buy or steal all suffer from the if you twist me I will work problem) question is . Having the boost box in Ohio and therefore not plugged in would this cause the tach to not work?
Or was Mr. Ockham correct and my tachometer is just broken?

 

[Miles Long]

Occam would suggest that you begin by checking for battery voltage at the brown supply wire to the tach (with the ignition on), and that the black wire is a true ground.
If all is well, try another source for the pulse signal (grey wire). Disconnect the grey at the tach, and use a jumper wire from another coil feed wire. Mr.Occam would of course use the easiest accessible under-the-seat coils to try this.
Cheers!

 

[tinman22]

No not proper diagnosis! I really didn't think to test the harness as it is brand new but I suppose it could be the problem. I did check for proper hookup but my books don't show the same color wires. Mine are grey, black and brown the books show green/yellow, black/red and black. Looking at the back of the unit the wire closest to the temp gauge is the brown with the black in the middle and the grey on the left. I saw it wired this way in several pics of the display in reference to aftermarket tach hookup.

 

[MaxMidnight]

Having the boost box in Ohio and therefore not plugged in would this cause the tach to not work?
Or was Mr. Ockham correct and my tachometer is just broken?

No, the taco feed comes directly from the ignition control units grey wire.
The grey to the fuel pump relay and V Boost control unit are tapped into this wire.
In addition to Mr Longs succinct suggestion you could also check the continuity of the grey wire from ICU to tacho.

If that and the feed and earths are OK then your tacho is probably Donald Ducked.

 

[tinman22]

I did some digging last night? (3:45 a) and found a better wiring diagram,at least for me. In the factory manual it looks like the tach feed comes straight from the v-boost controlle. The diagram I found last night (color) is a bit different.
I'm going over to check it out right now.

 

[tinman22]

Bad tach. Ockham was a smart guy.

 

[blaxmax]

I have a 5" with shift separate shift light for $30 plus shipping.

 

[tinman22]

Could you post some pics? Is there a mount? Definitely interested. Heck at 5" I might even be able to see it!

 

[blaxmax]

Could you post some pics? Is there a mount? Definitely interested. Heck at 5" I might even be able to see it!

I'll send them in an hour. It does have a mount.

 

[blaxmax]

Could you post some pics? Is there a mount? Definitely interested. Heck at 5" I might even be able to see it!

Never used.

 

[tinman22]

Sorry the response is so slow. Been so busy it doesn't really feel like a vacation! Looks good. Does PayPal work for you? I can take care of it in the morning, Ill get you an address too ship to somewhere in Florida.

 

[blaxmax]

Sorry the response is so slow. Been so busy it doesn't really feel like a vacation! Looks good. Does PayPal work for you? I can take care of it in the morning, Ill get you an address too ship to somewhere in Florida.

pm sent

 

[Felex]

Bad tach. Ockham was a smart guy.

Any tachometer repair options? Or still find one that works?