76 FXE tach wiring question
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Cruiser
Joined: Jul 2016
Posts: 241
Likes: 33
From: Syracuse IN
76 FXE tach wiring question
I can't find a new tach that is made for my 75 FXE, which sends its trigger signal from the voltage regulator ('74 and '75 models have this setup).
As an alternative I have a new tach. made for 76 and later models, that takes the trigger signal from the coil.
On back of the tach there are two posts.
One says 'IGN' and one says 'TRIG".
Does the 'IGN' connect to a switched 12V positive source, and the 'TRIG' connect to a coil post?
Thanks
As an alternative I have a new tach. made for 76 and later models, that takes the trigger signal from the coil.
On back of the tach there are two posts.
One says 'IGN' and one says 'TRIG".
Does the 'IGN' connect to a switched 12V positive source, and the 'TRIG' connect to a coil post?
Thanks
Thread Starter
|
Cruiser
Joined: Jul 2016
Posts: 241
Likes: 33
From: Syracuse IN
Checking the top coil post I determined that it was a switched 12V source, so ran a wire from there to the 'IGN' terminal on the tach.
Then ran a wire from the bottom of the coil to the 'TRIG' terminal on the tach.
Bike would not fire.
Disconnected the switched 12V wire from the top of the coil.
Bike would not fire.
Disconnected the wire from the bottom of the coil running to the 'TRIG' terminal and the bike fired.
Checked the connection at the tach to make sure the 'TRIG' connector wasn't touching anything other than the tach terminal post.
It was fine, there was clearance between the terminal connector and the tach case.
Tomorrow I'll pull the wires off both tach terminals to see if there's anything allowing a ground connection.
Maybe there's a nylon washer or similar missing that isolates the terminal connection and ensures the tach terminal post is the only contact.
Then ran a wire from the bottom of the coil to the 'TRIG' terminal on the tach.
Bike would not fire.
Disconnected the switched 12V wire from the top of the coil.
Bike would not fire.
Disconnected the wire from the bottom of the coil running to the 'TRIG' terminal and the bike fired.
Checked the connection at the tach to make sure the 'TRIG' connector wasn't touching anything other than the tach terminal post.
It was fine, there was clearance between the terminal connector and the tach case.
Tomorrow I'll pull the wires off both tach terminals to see if there's anything allowing a ground connection.
Maybe there's a nylon washer or similar missing that isolates the terminal connection and ensures the tach terminal post is the only contact.
Seasoned HDF Member
Joined: Jul 2014
Posts: 8,610
Likes: 3,377
From: Cental, MI
I have Never witnessed what is being described
What in the wide world of sports is Coil triggers doing down at the Charging system???
Coil triggers is what every tach I have ever seen, works on..
I guess I need Educated..
Edit; On my '79, (yes, Different from the '74 in the original charging system) the tach is simply wired at the coil.. White is 12v, Black (on mine), is triggers.. On Later models there is a Pink wire that is the Triggers to the Tach..
Bottom line, Every H-D Tach I have seen, triggers off trigger side of coil (even from points) and 12v from white wire side of Coil (comes from Run/Off handlebar switch)
One More Edit; It is important to Know, that the Real Dyna-S ignition Must Be wired White=12v... The Chiwanese Copy of the Dyna-S, Can Wire Bassackwards.. 12v Blue.. white triggers. This Can and Has screwed people up..
What in the wide world of sports is Coil triggers doing down at the Charging system???
Coil triggers is what every tach I have ever seen, works on..
I guess I need Educated..
Edit; On my '79, (yes, Different from the '74 in the original charging system) the tach is simply wired at the coil.. White is 12v, Black (on mine), is triggers.. On Later models there is a Pink wire that is the Triggers to the Tach..
Bottom line, Every H-D Tach I have seen, triggers off trigger side of coil (even from points) and 12v from white wire side of Coil (comes from Run/Off handlebar switch)
One More Edit; It is important to Know, that the Real Dyna-S ignition Must Be wired White=12v... The Chiwanese Copy of the Dyna-S, Can Wire Bassackwards.. 12v Blue.. white triggers. This Can and Has screwed people up..
Last edited by Racepres; Aug 24, 2022 at 09:36 AM.
Thread Starter
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Cruiser
Joined: Jul 2016
Posts: 241
Likes: 33
From: Syracuse IN
My factory manual for the '75 shows only the wiring for the tach that gets its signal from the voltage regulator.
'74 and '75 FXE had this setup.
Since I can't find a replacement tach that uses this system, I'm attempting to convert to the later model setup.
I have a NOS tach for a '76 and later FXE.
It is my understanding from others that the signal for 'TRIG' terminal on the tach comes from the spark coil.
And that the 'IGN' terminal on the tach needs to be attached to a 12V switched positive source.
So I attached a wire to the top of the spark coil as it is switched 12V positive.
If you know the correct way to connect the later model tach, I would appreciate the guidance.
'74 and '75 FXE had this setup.
Since I can't find a replacement tach that uses this system, I'm attempting to convert to the later model setup.
I have a NOS tach for a '76 and later FXE.
It is my understanding from others that the signal for 'TRIG' terminal on the tach comes from the spark coil.
And that the 'IGN' terminal on the tach needs to be attached to a 12V switched positive source.
So I attached a wire to the top of the spark coil as it is switched 12V positive.
If you know the correct way to connect the later model tach, I would appreciate the guidance.
Thread Starter
|
Cruiser
Joined: Jul 2016
Posts: 241
Likes: 33
From: Syracuse IN
EDIT
So it appears that I have the wiring correct for the later model tach.
I'll check for possible grounding at the tach itself.
If that doesn't correct it, I'll assume the tach is toast and look for another.
So it appears that I have the wiring correct for the later model tach.
I'll check for possible grounding at the tach itself.
If that doesn't correct it, I'll assume the tach is toast and look for another.
Seasoned HDF Member
Joined: Jul 2014
Posts: 8,610
Likes: 3,377
From: Cental, MI
My factory manual for the '75 shows only the wiring for the tach that gets its signal from the voltage regulator.
'74 and '75 FXE had this setup.
Since I can't find a replacement tach that uses this system, I'm attempting to convert to the later model setup.
I have a NOS tach for a '76 and later FXE.
It is my understanding from others that the signal for 'TRIG' terminal on the tach comes from the spark coil.
And that the 'IGN' terminal on the tach needs to be attached to a 12V switched positive source.
So I attached a wire to the top of the spark coil as it is switched 12V positive.
If you know the correct way to connect the later model tach, I would appreciate the guidance.
'74 and '75 FXE had this setup.
Since I can't find a replacement tach that uses this system, I'm attempting to convert to the later model setup.
I have a NOS tach for a '76 and later FXE.
It is my understanding from others that the signal for 'TRIG' terminal on the tach comes from the spark coil.
And that the 'IGN' terminal on the tach needs to be attached to a 12V switched positive source.
So I attached a wire to the top of the spark coil as it is switched 12V positive.
If you know the correct way to connect the later model tach, I would appreciate the guidance.
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Thread Starter
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Cruiser
Joined: Jul 2016
Posts: 241
Likes: 33
From: Syracuse IN
The signal wire must have been grounded.
The nylon surround on the signal post was missing, so I sliced a rubber electrical grommet in half and slipped it over the signal post to keep the connector away from the tach case.
My FXE has the gauge holder that uses metal cups on the bottom. There is enough lateral space in the mounting holes on the cup bottom to allow the cup to touch the signal terminal.
Carefully reassembled and the tach is working like a champ.
The nylon surround on the signal post was missing, so I sliced a rubber electrical grommet in half and slipped it over the signal post to keep the connector away from the tach case.
My FXE has the gauge holder that uses metal cups on the bottom. There is enough lateral space in the mounting holes on the cup bottom to allow the cup to touch the signal terminal.
Carefully reassembled and the tach is working like a champ.
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