tach wiring
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Road Master
Joined: Jun 2009
Posts: 1,126
Likes: 2
From: PA
tach wiring
Ok, I installed my 07 SE bars on my 09 SG several weeks ago, and I've gotten about 600 miles in so far. It was suggested that in time the needle would settle down and work right over time because that's how it happened when bberck initially bought them, but so far, it's still not working right.
I had originally tapped the signal wire into pin 3 on my PCV where it plugs into the ECM, but have since taken it all apart and bought the actual connector pin for the stock ECM plug. It's wired properly into pin 3 on the stock ECM plug now.
What happens is this: When I first start the bike, the tach will work, and idle, and if I get on the throttle a little, it will come up, and there is a slight delay before the tach comes back down to idle. When I start to ride, it's almost like it sticks at the top end, and unless I physically tap the tach, it won't come back down. Also, it won't go over 3000 rpm.
The only thing that I can think of is that the wire I used to connect the signal is bigger, and possibly causing a resistance issue. Is that possible?
Do you guys have any other clues you could offer up?
I don't doubt for one minute that it's something I've done, or not done, when installing it, I just, for the life of me, can't figure out what it could be.
Also, this was installed on a 08 SG previously, and mine is an 09. I do have the service manual, and I'm fairly certain that it's pin 3 on mine, just as it was on the 08.
I had originally tapped the signal wire into pin 3 on my PCV where it plugs into the ECM, but have since taken it all apart and bought the actual connector pin for the stock ECM plug. It's wired properly into pin 3 on the stock ECM plug now.
What happens is this: When I first start the bike, the tach will work, and idle, and if I get on the throttle a little, it will come up, and there is a slight delay before the tach comes back down to idle. When I start to ride, it's almost like it sticks at the top end, and unless I physically tap the tach, it won't come back down. Also, it won't go over 3000 rpm.
The only thing that I can think of is that the wire I used to connect the signal is bigger, and possibly causing a resistance issue. Is that possible?
Do you guys have any other clues you could offer up?
I don't doubt for one minute that it's something I've done, or not done, when installing it, I just, for the life of me, can't figure out what it could be.
Also, this was installed on a 08 SG previously, and mine is an 09. I do have the service manual, and I'm fairly certain that it's pin 3 on mine, just as it was on the 08.
Last edited by Pa-Rider; Mar 18, 2010 at 09:18 PM.
Club Member
Joined: May 2006
Posts: 14,564
Likes: 9,223
From: the 50s & the 60s
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If it was me, I would either.........
.....pick up the signal right at the speedo harness. (picture below)
DataBus/DataLink
the hot and ground are right there as well.
or
.....buy the correct harness and plug in where it says To Main Harness (below)
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Road Warrior
Joined: Apr 2009
Posts: 1,360
Likes: 4
The ECU pin 3 is the most reliable way to obtain a tach signal.
Sounds to me like you have a defective tach, perhaps one that the needle rubs a bit either on the glass or scale, tapping the tach is a dead give away.. I've had a few aftermarket tachs for the car do this after rough use, the axle pin that needle swings on bends and friction builds up. Not sure your tach has a warrantee of if it can be taken apart to fix the obstruction or bend axle pin or squirt some silicon lube in to loosen thing up.. they look pretty tightly sealed, at least the one in front of me does.
Sounds to me like you have a defective tach, perhaps one that the needle rubs a bit either on the glass or scale, tapping the tach is a dead give away.. I've had a few aftermarket tachs for the car do this after rough use, the axle pin that needle swings on bends and friction builds up. Not sure your tach has a warrantee of if it can be taken apart to fix the obstruction or bend axle pin or squirt some silicon lube in to loosen thing up.. they look pretty tightly sealed, at least the one in front of me does.
Last edited by ColdCase; Mar 19, 2010 at 10:28 AM.
Elite HDF Member
Joined: May 2008
Posts: 4,579
Likes: 10
From: S.E. MO
I will add some additional info and jackjr keep me informed on wether you get it working right or not.
Mud he has a wiring Harness from the 07 FXDSE that has the tach hook ups on it. On my bike it worked for the ground and the power but if you followed the signal wire to the main harness the spot was blank on my bike. I know on some they can pick up the signal at the speedo but on my 08 this wasnt a option.
Jackjr you may follow the tach signal wire from the speedo harness and see if your bikes main harness has a wire on it. If it does try getting the signal from there. Also check the ground since the tach cup is kind of tight and make sure it isnt making contact maybe even put a piece of tap over it.
This tach did the same thing to me over a year ago when I first installed it. I too thought it was a mechanical issue but after a couple rides it started working properly. A year and over 10k miles it never did it again and I never thought anymore about it. This makes me think it may be a signal or ground issue that worked out on its own for me. If it is mechanical the only thing I did when I was messing with it was take the bike out and run the RPM's up real high a few times. Maybe this helped I am really not sure.
Mud he has a wiring Harness from the 07 FXDSE that has the tach hook ups on it. On my bike it worked for the ground and the power but if you followed the signal wire to the main harness the spot was blank on my bike. I know on some they can pick up the signal at the speedo but on my 08 this wasnt a option.
Jackjr you may follow the tach signal wire from the speedo harness and see if your bikes main harness has a wire on it. If it does try getting the signal from there. Also check the ground since the tach cup is kind of tight and make sure it isnt making contact maybe even put a piece of tap over it.
This tach did the same thing to me over a year ago when I first installed it. I too thought it was a mechanical issue but after a couple rides it started working properly. A year and over 10k miles it never did it again and I never thought anymore about it. This makes me think it may be a signal or ground issue that worked out on its own for me. If it is mechanical the only thing I did when I was messing with it was take the bike out and run the RPM's up real high a few times. Maybe this helped I am really not sure.
Thread Starter
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Road Master
Joined: Jun 2009
Posts: 1,126
Likes: 2
From: PA
I'm going to take a look at things again when I get home, and hopefully get it resolved. Pin 3 on the plug side of the stock ecm plug was blank, but I bought the pins that go in there from the local dealer, and wired it all up. Prior to that I was tapped into the PCV plug. Same effect. When I get home this evening I'll pull the harness out of the neck and see if wiring it through the harness will make a difference. I'll keep you all posted.
(and I'll pull the cup off the tach and check that as well - sure can't hurt..)
(and I'll pull the cup off the tach and check that as well - sure can't hurt..)
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2nd Gear
Joined: Apr 2010
Posts: 6
Likes: 0
From: Rockwell, NC
I am also having a problem with the HD tach. I found the wires coming out of the speedometer and hooked them up correctly. When I turn on the ignition key, the tach needle immediately becomes erratic and jumps all over the place up to around 2K RPM. When I start the bike, it continues to be erratic and is not responsive to increasing the revs. I redid the datalink connection and feel I have a good connection. I also ran a ground wire directly to the battery. After reading one other post, I found the correct wire at the ECM and tapped into it there. Same results.
Last edited by jerhofer; Apr 24, 2010 at 06:14 PM.
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