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J-Man
Dodge Dakota
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2/21/2004
19:25:37
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 Subject: Tachometers
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Message:
I bought a cheap aftermarket tachometer for my '96 3.9. In the installation instructions it says to connect such and such a wire from the tachometer to the negative terminal on the ignition coil. When I look at my ignition coil, I see two wires coming off the negative terminal. Great! Which one is what? Is one of them a ground wire? Does anyone know what I am supposed to be doing here!
Thanks J-Man
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droogie
Dodge Dakota
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2/21/2004
20:51:31
| RE: Tachometers
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Message:
Check with Larry, I'm sure he would know if no-one else.
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J and J Auto
GenII
 
2/21/2004
21:06:40
| RE: Tachometers
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Message:
OK
There are 2 connections on the coil
I wish they would mark them but they don't
+ side
- side
you need to go on the minus side and the other
wire from the tach to ground
The light on the tack you need to pick up your
dash lights in the cab, usualy you can just go
on 1 side of the insterment light fuse for that
Here is how you tell which is which
First go in the power dist box and pull the fuel
pump relay its a squre box it looks like
now unplug the 2 wire connector on the coil and
with a volt meter black - lead on a good ground
red + lead from volt meter one of the coil wires
Have someone crank the motor over
one will run a steady voltage + side
one side will go up and down that is - signal
side that you need.
you can just use a cheap anolog volt meter you
don't need a digital to check these.
find the - minus pulsing side and that is the one
you need.
Now put your fuel relay back in and tap the - wire
run the other to ground and your tach will work
The reason you pull the fuel pump relay is so you
do not load the motor with fuel while turning over
to find which wire is which.
Larry
J&J Auto
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J-Man
Dodge Dakota
JOIN HERE
2/21/2004
21:19:26
| RE: Tachometers
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Message:
Thanks Larry,
You wouldn't happen to know what color stripes were on that pulsing wire, would you? I don't really have anyone around right now to crank the engine for me, but I guess I might have to wait.
Thanks again
J-Man
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J and J Auto
GenII
2/21/2004
21:39:04
| RE: Tachometers
IP: Logged
Message:
I am not sure on the 96
grey and black with a strip but don't know which
is which off hand
best to check them unless you have a wire diagram
handy, I don't right now all packed up for the
move to the new shop
You could do it yourself just put the - jam in
neg bat cable and the + in 1 side set the meter
where you could see it while turning over, I
always end up checking myself the guys always
bitch when I bother them for something simple like
that LOL
roll the window down and reach in and turn it over
Larry
J&J Auto
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J-Man
Dodge Dakota
JOIN HERE
2/21/2004
21:43:29
| RE: Tachometers
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Message:
Thanks tons Larry. It is really appreciated! I haven't been able to find a shop or a dealer yet who knew.
J-Man
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J and J Auto
GenII
2/21/2004
22:09:19
| RE: Tachometers
IP: Logged
Message:
The modern technition is taught to hook the
vehicle to there diagnostic machine and if the
machine says there is nothing wrong they tell the
customer the same nothing wrong
They do not have a clue as to how these things
work, what does what and why or how to fix
anything just replace parts if they show bad, I
think they are also taught how to bull $hit the
customer into beleaving it
I have no use for the modern tech even when you
talk to them they are completly lost
Larry
J&J Auto
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killerdakota@
Dodge Dakota
JOIN HERE
2/22/2004
08:44:23
| RE: Tachometers
IP: Logged
Message:
if you look at the msd install pdf they say the colors
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piston
Gen II
2/22/2004
18:00:29
| RE: Tachometers
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Message:
Larry, That is something I pride myself on while at work. In school we were taught how to diagnos but at work everyone just replaces parts its like an assembly line. They guys at work give me crap for checking but I get a heck of a lot less comebacks, sorry I know its off topic but I feel strongly and agree with larry
Keep The Shiny Side Up
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J-Man
Dodge Dakota
JOIN HERE
4/04/2004
18:42:46
|  RE: Tachometers
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Message:
Well, finally got around to trying to hook up the tach today, and mangaed to get nowhere. I checked to connector for the pulsing signal, didn't find one, so I took my best guess and spliced in. No dice. Alright, ran new wire and spliced in to the other one, that way if I was wrong, and actaully had it right the first time, then I could just switch back. So anyway, I can't get anything to happen. Nothing.
My tach has 4 wires:
black - ground
green - neg. coil
red - "on" selector on ignition
white - light
My question is this....
Do I have to have the red wire connected in order for the tach to work? I just connected the black and green, hoping to see somehting before I went ahead with the red and white wires. But does the tach require power to work? I though just hooking up the neg coild and ground should at least give me something. If someone can help me, I would really appreciate it. I want to get this thing hooked up today if possible!
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uh
Dodge Dakota
JOIN HERE
4/04/2004
19:49:41
| RE: Tachometers
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Message:
the only wire you don't need to connect is the one for the night lighting. if you leave any of the other wires off it don't work. after re-reading your post I see that you left off the red wire that powers the tach as does the black. the green wire to is it the signal wire. you left off the positive power wire and then you want to know why it don't work? aint that a bit like wiring a lightbulb to only one wire?
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J-Man
Dodge Dakota
JOIN HERE
4/04/2004
20:06:27
| RE: Tachometers
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Message:
I though the signal for the tach powered it as well.
Thanks anyway for answering my question.
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J and J Auto
GenII
4/04/2004
21:32:24
| RE: Tachometers
IP: Logged
Message:
Some tacks also need 12 volt
I have some old sun super tachs that requre a
ground, coil signal and a 12 volt red wire.
hook the red wire to the power
Larry
J&J Auto
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Scotty89Dak
Dodge Dakota
JOIN HERE
4/04/2004
21:54:43
| RE: Tachometers
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Message:
Luckily i'm working with a bunch of old fashion techs in my shop that are teaching me the tricks of the trade.
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J-Man
Dodge Dakota
JOIN HERE
4/04/2004
23:10:45
| RE: Tachometers
IP: Logged
Message:
Thanks guys,
Gott'er all hooked up and seems to be working great (as great as a $25 tach can be expected to work, anyway. I just have the lighting wire jammed in with the fuse for the lights right now, but I think I am going to hook it up to the dimmer switch when I have some more daylight left.
Anyway, Thanks again!
J-Man
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