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67 tach wiring dilemma

6

67390GT

New Member
I will try to explain my problem as best I can. I have a 1967 390 GT, originally came with a tach and all the proper wiring still exists(small miracle). Somewhere over the last 45 yrs the stock Ford tach went MIA, replace by some cheap piece of crap. Recently I purchased a Mustang tach cluster for a reasonably
decent price(compared to ebay). It was from a 1968 Mustang. I hooked up all the wiring(except tach) for the dash cluster and everything worked as designed: temp and fuel gauges and warning lights for alt, oil and brakes and the car started and ran fine. Next I located the connection that I need to plug into for the tach: pink resistor and red/yellow stripe wires. So far so good. BUT......the pink resistor wire has a male bullet connector(factory)and so does the black wire from the tach; likewise the ign wire(red/yellow stripe and the red wire from the tach have female bullet connectors! Huh? The red wire was repaired in the past sometime, but the black wire appears to be a stock Ford connection.
This dilemma leaves me with a couple of questions:
Do I switch the bullet connectors and hook up the tach as per wiring diagrams (tach red wire to red/yellow stripe and tach black wire to pink resistor wire)?
Do I hook the tach up with the wires as they are ie 'backwards' (tach red wire to pink resistor wire, black to red/yellow stripe) ??
Are 67 and 68 mustangs wired differently? I have seen plenty of differences.
What if the tach is hooked up 'backwards' ? Does it matter?
Why do things like this happen?
What is life?
Of course I don't know if the tach works or not, which doesn't help matters.
I hope this all makes sense.
Thanks for any knowledgeable help,
Tom
 
"67390GT" said:
Why do things like this happen?
Click to expand...
Murphy's law...

I wired up a 67 Cougar Tach in my non-tach 67 Mustang. I made a diagram of how I wired it. I don't know if that helps you any but it's all I got...
 

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From the main harness: pink resistor wire ending up in a male bullet; red/yellow in a female bullet.

Typically, one simply mates the male bullet on the main harness to the female bullet from the tach cluster and vice versa. My 1966 diagrams has the pink resistor wire going to the black tach wire.

There is almost no information on 67/68 tachs in the public domain, but I would keep with your current understanding of wire colors.
 
Thanks Mid for the reply. That's what my main harness has: Pink resistor male bullet, Red/yellow female. But the tach red wire is female and the tach black is male, which seems to be the opposite of the way it should be. Normally the black tach wire connects to the pink resistor wire. correct? but both of these are males. Any idea of the consequences of hooking resistor wire to red wire and red/yellow to black(backwards)?
Thanks, Tom
 
Tarified 1:I forgot about Murphy's law, that's probably why I just lost power to my garage, or is that related to the tach wiring too?
Your diagram is the way it should be, but the bullet connectors on my tach are on the 'wrong' wires. the red wire is female, should be male
 
Change the gender of the wires on the tach. Someone has monkeyed with it.

Probably what happened is that a PO opened the case, and found the two wires to the transformer broken. Not knowing which lead goes where, he may have soldered them on backwards. If true, then one really doesn't know the correct orientation of the leads. Open the case carefully and look for splices or repairs at the other ends of the wires.
 
"67390GT" said:
Tarified 1:I forgot about Murphy's law, that's probably why I just lost power to my garage, or is that related to the tach wiring too?
Your diagram is the way it should be, but the bullet connectors on my tach are on the 'wrong' wires. the red wire is female, should be male
Click to expand...
My car and Tach didn't have any factory connectors. Sorry I couldn't be more help, Murphy has been to my house a lot. Glad to see he is not stuck in just one place! Good Luck and welcome to the Fix
 
Thanks you guys for the help. That was my thought too, just switch the ends and go for it. Tach most likely doesn't work anyway. Cant forget the corollary to Murphys law: Given a 50/50 chance, you will choose wrong
Thanks again
 
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