Rpm not working with haltech Ecu . Help pls

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Leo40z

Well-Known Forum User
Hi all

My rpm doesn't work in my 1974 240z ever since I fitted my haltech sprint 500 Ecu .I'm no longer using a dizzy as I'm using a coilpack .

On the laptop everything is enabled and I've gone through voltage settings but still nothing .i do get a rpm reading once the Ecu is plugged into my laptop but I don't fancy driving around with on my passenger seat . Lol

I've taken the signal feed wire from the back of the tacho black with white wire and wired into the tacho output of the haltech . But still nothing .

Can the tacho work with this setup ?

Many thanks

Leo
 
L

Leo40z

Well-Known Forum User
Nice one Sean . If the tacho was a easy job to remove i might of gone for the second option. I'm not removing that dash again that's for sure . Lol

Try and come past next week Sean if your about . ? Or I can come to you depending on weather . Lol


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Sean287

Sean287

Well-Known Forum User
Amen to that, the gauges are a right ballache to work on! We'll sort something out mate. I'm not back to work until the new year. I'll drop you a message after Crimbo.
 
Farmer42

Farmer42

Club Member
Leo40z said:
Nice one Sean . If the tacho was a easy job to remove i might of gone for the second option. I'm not removing that dash again that's for sure . Lol


It shouldn't be difficult to remove the Tach on it's own without removing the dash. I'm sure someone will correct me if i am wrong but on the older models, unless it has been changed, the gauge is held in place by 3 butterfly nuts to a bracket at the back. You should be able to undo these and push the tach forward, sliding it out of the dash.

Otherwise, I had a similar problem a while back when I fitted electronic ignition. I followed the wiring diagrams from the following link which showed that I needed to join 2 wires together that led to the coil. I know you have gotten rid of the coil but the wiring should still be the same that led to it.

http://atlanticz.ca/zclub/techtips/distributor/index.html

Might be worth a try.

Good luck
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L

Leo40z

Well-Known Forum User
Farmer42 said:
Leo40z said:
Nice one Sean . If the tacho was a easy job to remove i might of gone for the second option. I'm not removing that dash again that's for sure . Lol


It shouldn't be difficult to remove the Tach on it's own without removing the dash. I'm sure someone will correct me if i am wrong but on the older models, unless it has been changed, the gauge is held in place by 3 butterfly nuts to a bracket at the back. You should be able to undo these and push the tach forward, sliding it out of the dash.

Otherwise, I had a similar problem a while back when I fitted electronic ignition. I followed the wiring diagrams from the following link which showed that I needed to join 2 wires together that led to the coil. I know you have gotten rid of the coil but the wiring should still be the same that led to it.

http://atlanticz.ca/zclub/techtips/distributor/index.html

Might be worth a try.

Good luck
Click to expand...


Morning mate .

I've just spent an hour going through the net . You are right about the tacho ,it can be removed from the front but the wing nuts could be a pain .lol

I removed by dash about a year ago as my loom needed changing . I think I bent the tabs back and just removed them from the back .

I will 100% give it a go . As for the wiring I'll have to go through it .


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johnymd

johnymd

Club Member
You probably already know by now that the 240 tacho uses an inductive pickup to sense the spikes in the coil. It doesn't just receive an input signal. Connecting one of the wires from the tacho loop to the ECU tacho output will not work. I got mine working with my 1jz ecu but it was so long ago, I cant remember how. Then I changes to an autometer gauge so I cant even see how I did it. There should be a whole load of info on the net as its a really commonly asked question.

Sorry I cant help.
 
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Leo40z

Well-Known Forum User
johnymd said:
You probably already know by now that the 240 tacho uses an inductive pickup to sense the spikes in the coil. It doesn't just receive an input signal. Connecting one of the wires from the tacho loop to the ECU tacho output will not work. I got mine working with my 1jz ecu but it was so long ago, I cant remember how. Then I changes to an autometer gauge so I cant even see how I did it. There should be a whole load of info on the net as its a really commonly asked question.

Sorry I cant help.
Click to expand...


Come on johnymd you must remember something ? Lol


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S

SKiddell

Well-Known Forum User
Correct me someone but we there not 2 different types of Tacho, one voltage sense (early car) and the other more common current sense (later cars)

Mines definitely current sense (white coiled wire at the back of the tacho) I used the original coil feed, it now feeds the coil pack and produces an identical current spike which is then sensed by the tacho (as John says), works fine and has been for 10 years now.
 
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Leo40z

Well-Known Forum User
If I remember correctly when doing the wiring for the haltech we used the black with white wire so does that means that's the early or later model ?
 
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Leo40z

Well-Known Forum User
Which wire do I connect my tacho wire to ?



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Leo40z

Well-Known Forum User
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S

SKiddell

Well-Known Forum User
As previously mentioned, that white wire is the inductive loop and feeds the original coil

Try this...... leave everything as is...take the live feed (to the old coil) in the engine bay and directly feed the coilpack (assuming the Haltech is current sinking on the coil lines)or the live you have used to feed the coilpack, break into it and pass it through the white loop
 
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Leo40z

Well-Known Forum User
Sort of confused now .

I remember checking for continuity from the back of the tacho to the engine bay and the black and white was my circuit . But I can remember which wire it was on the back of the gauge .

I've bought a Dakota tacho interface so I need to fit that.

All my wiring is completely finished to high standard and I don't want to start ripping things apart .lol

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Leo40z

Well-Known Forum User
I know mate . Lol I just powered it up last light to make sure it works . I've just now found the tacho wire so I'm going to fit and see what happens


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