KA with stock Tach (IT WORKS!)

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Re: KA with stock Tach (IT WORKS!)

Postby Dimebag » 22 Mar 2008 07:44

Hey, right on - I'm glad it all worked out for you! nice work with the splices.
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Re: KA with stock Tach (IT WORKS!)

Postby DMS » 06 Apr 2008 13:07

I have a little experience with the Nissan Ignitor systems. Alot of the Nissan tach circuits with an ignitor in the circuit as the signal have a resistor in series on the neg signal wire from the coil.

i cant remember if the 240sx engines had the same thing. I know that the older VG30 vehicles and 280zxt systems had this resistor for sure. Its been along time since I touched one of those systems and cant remimber, but i think the resistor is just there to drop the voltage... which means you might be able to burn up your tach. Its located under the driver side dash in most vehicles and is usually forgotten when everything else gets pulled. Just some extra input

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Re: KA with stock Tach (IT WORKS!)

Postby Dimebag » 06 Apr 2008 15:08

The resistor you are talking about is shown in the wiring diagram. Considering the way the stock tach measures "flyback impulses" on the positive side of the coil, I don't imagine it could be burned out by this resistor.
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Re: KA with stock Tach (IT WORKS!)

Postby DMS » 25 Apr 2008 09:55

I meant if you didnt have the resistor in place.

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Re: KA with stock Tach (IT WORKS!)

Postby 510rob » 25 Apr 2008 15:28

The white wire going through the tach is exactly that - a wire passing through a pulse transformer. In plain english, that means the tach is electrically isolated from the ignition circuit. That can be taken one step further to say the current limit of the system is based on the heat capacity of the wire+insulation of that white wire & the pulse transformer...

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Re: KA with stock Tach (IT WORKS!)

Postby inline4 » 08 Apr 2009 22:23

I'm having a hell of a time getting this to work, am I that dense?

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Re: KA with stock Tach (IT WORKS!)

Postby Dimebag » 09 Apr 2009 08:03

ok, quick review.

1 - Identify connector F30 - it is a two-wire connector on the bottom of the 240 coil next to the high-tension coil wire that goes to the distributor.

2 - the two wires in connector F30 are color coded. The one you are interested in is B/R (black w/ red stripe)

3 - you will need to cut that B/R wire and splice the two white wires from the factory tach to each end of the B/R wire you just cut. There is a great picture showing this with blue splices.

4 - Don't forget that the factory tach itself has a power wire that needs to be hooked up.

5 - as per the previous instructions, if you think you have it all hooked up correctly and it doesn't work, try swapping the ends of the the two white wires where they are connected to the B/R wire.

good luck.
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Re: KA with stock Tach (IT WORKS!)

Postby inline4 » 10 Apr 2009 12:12

I only have the three wires coming out of the black grommet.

I dont have the two white wires. am I missing something?

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Re: KA with stock Tach (IT WORKS!)

Postby Dimebag » 10 Apr 2009 21:31

inline4 wrote:I only have the three wires coming out of the black grommet.

I dont have the two white wires. am I missing something?


Are you hooking up a factory tach? That's what these instructions are for. If you don't have the two white wires, then I'm guessing you have something else.

post of photo of what you do have.
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Re: KA with stock Tach (IT WORKS!)

Postby inline4 » 10 Apr 2009 21:52

Image

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Re: KA with stock Tach (IT WORKS!)

Postby Dimebag » 11 Apr 2009 12:34

hmmm, interesting. Here is what an unadulterated factory tach looks like.

IMGP3844.JPG


Maybe yours was 'modernized'. Are your wires labeled?
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Re: KA with stock Tach (IT WORKS!)

Postby rnorrish » 11 Apr 2009 14:16

there is definitely something missing there! :shock:
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Re: KA with stock Tach (IT WORKS!)

Postby inline4 » 12 Apr 2009 00:02

peering inside, there seems to be some resistors soldered in. this tach worked when i had the L16 in the car, I just don't particularly want a dead gauge. it had 2 wires running to the coil, and one attached to one of the wires behind the dash.

I also had I believe some type of hitachi electronic ignition?

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Re: KA with stock Tach (IT WORKS!)

Postby arkitekz » 13 Apr 2009 09:22

Your right Inline, your tach seems to be in different condition than mine. You may have to chime one of the electrical gurus in here to help you figure it out.


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