Bouncing Tachometer

Energy One
cvegmond

cvegmond

Member
I've read all the posts on the issues with the tachometer and I've come to the conclusion that either the printed board of the tachometer or the EHC is screwed up.

I ride it the worst of rain storms to work and wash this 2007 K-9 at the car wash. I've had the bike 4 months and the electrical system is a "freak".:job:

The BD Dealer doen't seem to deal in BD parts. They don't have the EHC or the tach board, not can they promise to get them. I feel very un-loved.

QUESTION: "IF" I install this "wire-plus" EHC elimination kit will the tachometer behave as it used to...before my repeated wet high speed commutes? This Jake Low Down Chopper fellow seem straight up but this wire-plus set-up isn't cheap.

What do you think?

thank you, cvegmond

P.S. My first post our your helpful forum.
 
BigDogBro1

BigDogBro1

Made in the USA
Your introduction post please,

The tach signal wire comes from the S&S ignition module and doesn't go through the EHC controller. It is a wire connection most likely if the bike is running okay. You need to clean all connectors and install dielectric grease in them. Could be connection in speedo head as well.

Check all the tach signal path connections first.

There are many posts here on it. Check the How to's for help as well.

http://www.bigdogbiker.com/forums/how/218-how-where-shrink-wrap-your-wires.html

A Wire+ won't help this.

 
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cvegmond

cvegmond

Member
The Tach and the Intro Post

Thanks. I check all the plugs associated with the tachometer. I read on this forum that the rpm sensor sends a signal to the ignition module and to the EHC. The EHC passes that signal to the tachometer.

I could be all wet.

When I get home tonight I will check the wiring diagrams in the service manual.

The tach went wacko during a 110 mph burst down the beltway and not during a rain storm. Perhaps something has vibrated loose. I will open the speedometer housing and check.

I'll work on this intoduction now.

cvegmond
 
BigDogBro1

BigDogBro1

Made in the USA
Nice intro....

YEP I'm afraid, you are all wet.

Before you rip apart the speedo head, it would be easier to check THOSE connectors in the tach signal path as I recommended earlier.

The cam sensor sends the RPM signal to the S&S ignition module.
BUT if you look at the schematic you will see that the tach signal DOES NOT PASS THROUGH THE EHC CONTROLLER CHIP ON ITS WAY TO THE SPEEDO HEAD.

The EHC box is just a connection point and the tach signal is only used to log RPM cruise data and such.

The EHC (controller chip) is wired in a parallel circuit.

Like I mentioned earlier, if your engine is running fine NOW the the EHC is not the cause.
 
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Coolbreeze

Coolbreeze

Active Member
As the tach board gets wet and dries over and over, it starts to corrode the solder joints on the back of the board. You don't have an S&S ignition in your K-9. You have a Thunder Heart ignition. If all your connections are good, you need a tach board. Pull your tank. You could have some rubbed wires under.
 
DRBarnhart

DRBarnhart

Insert title here...
We may be saying the same thing here but this is what I get from the wiring diagram...

The crank position sensor sends pulses to the ignition module. The ignition module, among other things, translates these pulses into RPM which is sent to pin A-5 on the EHC. Inside the EHC the tach signal continues on providing a tap to the optional tach port at pin B-48 and provides an input to the main controller so it knows what RPM's you've been running at. The signal then continues on exiting at pin B-47, running through a couple of connectors, ending up at pin H or the tach PCB.

So what does all this mean? That there's a few connectors to check including those on the EHC. Also, it would be possible for the EHC to be causing your problem since the signal does go through it.

I'd start with checking for crud on the sensor, then check connectors, then check the tach board itself for corrosion/loose solder joints, and finally do a general visual check of the wiring to check for chafes.

See what you find and go from there...

My :zz2cents:

Dennis
 
Brew

Brew

Troop Supporter
I say pull your sensor and clean it and see if that helps. Sometimes they collect crud and you don't get a good signal which can cause the jumping problem...Just saying!
 
jimizee028

jimizee028

TRUE COLORS COLLISION
where is sensor located??? of course I have this same issue ,but after this being the 3rd speedo on my bike I refuse to replace it or any parts of it,I really would like the new speedo off the 2010's if possible to use with our bikes...I also have 2007....so wheres the sensor guys????
 
Brew

Brew

Troop Supporter
It located on the right side corner of your transmission and has a single screw that holds it on...:2thumbs:
 
DRBarnhart

DRBarnhart

Insert title here...
The crank position sensor is on the front of the engine, left side (near the top of the oil filter), just inboard of the connector going to the stator.

Dennis
 
Brew

Brew

Troop Supporter
Yep your right Dennis, I had the speedo meter in mind. My bad...:zzdisappointed: That's me and my slective reading again...
 
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garv

garv

Member
My tach started doing the same thing, and it ended up being my charging system was going bad. shortly after the stator went so i changed the entire charging system and the problem was fixed.
 
cvegmond

cvegmond

Member
garv said:
My tach started doing the same thing, and it ended up being my charging system was going bad. shortly after the stator went so i changed the entire charging system and the problem was fixed.
Click to expand...
My charging system seems to be working fine. The battery is not dead and the bike starts.

I check the crank sensor. Cleaned it but it looks fine.

Then I checked all the plugs from the sensor to the speedometer housing. Everything is clean, dry and plugged in tight.

I will open the speedometer housing tomorrow.

Where is the ignition module located? To my surprise it's not behind the timing cover, like a Harley. Is it the metal box next to this EHC?

Thanks, Cor.

P.S. Removing the plastic battery covers are a pain in ass.
 
cvegmond

cvegmond

Member
Dirty sensor

Brew454 said:
Also check your sensor it have crud on it...
Click to expand...
I would assume that if the sensor is dirty and missing the crank pick up then the bike would run bad, as the ignition module would miss the engines timing.

If the bike runs good but the tach is bouncing around then the issue has to be between the ignition module and the tach printed control board in the speedometer housing?
 
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