New Combination Digital Speedometer/Analog Tachometer

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Jul 4, 2010 | 02:10 PM

#41

FBRR

Tourer

Joined: May 2010

Posts: 348

Likes: 5

From: The mitten state

While I am not an expert on all things Harley, I am a retired calibration engineer. The difference between years, even with the same "ECM" part number, does not mean the same SOFTWARE or calibration.

My guess is with the change in transmissions and gear ratios, the Software "pulse per mile" to the speedo will be wrong, if you use the 09 or 10, part number. While the TACH may or may not have the same input, you may have an issue that your speedo is not acurate with past model years. That would be my guess why it is model year specific!Hope that helps!

Jul 4, 2010 | 05:48 PM

#42

dyna rider

Club Member

Joined: Dec 2007

Posts: 4,192

Likes: 168

From: Knoxville, Tn

Speedo /Tach

I'm pretty sure the signal data that feeds the tach is from the crank position sensor. That why the coil doesn't work for the tach signal on the newer bikes.

Jul 4, 2010 | 08:03 PM

#43

8541hog

Ultimate HDF Member

Joined: May 2008

Posts: 6,642

Likes: 48

From: Ogden, UT

Quote:

Originally Posted by dyna rider

I'm pretty sure the signal data that feeds the tach is from the crank position sensor. That why the coil doesn't work for the tach signal on the newer bikes.

That is true on HD tachs, but aftermarket tachs can run on the coil signal, mine does. Just depends on the tach.

Jul 5, 2010 | 07:49 AM

#44

rjohn61987

Intermediate

Joined: Oct 2009

Posts: 33

Likes: 0

From: Show Low, AZ White Mtns

Works fine on my '06 WG. Dealer puts your miles on the new speedo/tach and gives you DMV form. Mine was plug and play.

Jul 5, 2010 | 09:27 AM

#45

Airborne350G

Thread Starter

Club Member

Joined: Jun 2007

Posts: 3,435

Likes: 28

From: Living in open carry state :D

Quote:

Originally Posted by rjohn61987

Works fine on my '06 WG. Dealer puts your miles on the new speedo/tach and gives you DMV form. Mine was plug and play.

Thanks, you are another one that states it is working on an older model. Good to know.

Jul 6, 2010 | 10:58 PM

#46

lampshade29

6th Gear

Joined: Jul 2008

Posts: 13

Likes: 0

From: Goodyear,AZ

I am have been mulling this combo since I saw it on the Softtail CVO model when that came out. I really want to buy this for my 08 FXDC but I was wondering the difference between the 09 vs 08 now that I hear it works with older bikes that is great news.

I have two questions how did the older bikes get the tach to work and is the odometer accurate?

Thanks guys.

Jul 7, 2010 | 07:59 AM

#47

ColdCase

Road Warrior

Joined: Apr 2009

Posts: 1,360

Likes: 4

Quote:

Originally Posted by 8541hog

Stock HD tachs on bikes with ECM's do get the tach signal on the Data Bus, I learned this when I installed my Dakota Digital, that is why HD tachs are plug-n-play.
You can get a tach signal from the front cylinder coil if the tach you are hooking up will accept the signal, if it is a HD tach designed for the ECM, most likely that wont work.

ECU pin three has a tach signal. HD and other aftermarket tachs work well off that signal. The tach signal at the speedo connector is less reliable. You can use a tuner like TTS to adjust for gear ratio changes, and bring the speedo back into calibration.