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JZ motors in everything!
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Okay THAT didn't work.

I jumped the resistor in the tach and it changed nothing. No tach unless i connect the wire from ignitor to the tach signal wire at the cluster harness plug.

With the wire connected tach works but no AC (no engine speed signal to A/C amplifier)

Where is the car supposed to get the tach signal from? Arghhhh...
 

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The Great Kruso
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You're working with an Aristo ECU, that is the only variance, everyone else here is referring to the TT ECU.
 

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Discussion Starter #26
that fix did work btw, I have usdm ECU / Harness in a 95 supra
just jumping that resitor did the trick
 

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2JZA70
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it should, there's nothing different from an NA tach other than a couple thousands rpm's more and a very cool logo ;)
I figured it would be a good option for those who dont want to pay $500 for a TT TRD tach when the TRD NA version can be had for $175. Visually they are the same.
 

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Hook up the wire from the TT Igniter A1 terminal (ext) to the blk/wht wire on the Diag connector (tach) and your good to go. Does not cost one dime and works just fine.
can someone please clarify and explain this step to more detail? is just jumping the resistor not enough?

thanks.. i have been waiting for this fix a long time.
 

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Raising the BAR
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?? This IS what they're talking about, how would that be hijacking the thread?



Thats what I was under the impression of but Kirk is right. Here's the writeup copied and pasted from Clubna-t as posted by Captdale.

Take out the tach and look at the circuit board. See the 33K ? resistor on the top right hand corner. Jumper the resistor with a wire. Put it all back together. Hook up the wire from the TT Igniter A1 terminal (ext) to the blk/wht wire on the Diag connector (tach) and your good to go. Does not cost one dime and works just fine.

Apparently the NA tach takes a high level signal developed by the distributor/Igniter circuit. The TT ECU and Igniter put out a low level signal for the tach. The NA tach current limits its high level signal by putting a 33K ? resistor in series with the input. When you jump the resistor the tach is no longer current limited and the low level signal from either the TT ECU (A16) or the TT Igniter either one will drive the NA tach just fine.




I have personally done this and it worked perfectly.
 

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^^^ That's what I did as well on my NA to TT mkiv
 

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When I plugged up my scanner I noticed that my tach is actually off by almost 500 rpms by redline when I jumpered the resistor like in the post. It's only off by 100 rpm at idle though, it seems it gets worse the higher rpm. I bought a used TT tach and measured the resistor and it's a 52k resistor. I went to radioshack and paid 99 cents for a pack of 52k resistors and put that in place of the NA 33k and it works perfect. It's not off at all anymore. Hope that helps for other cheap solutions. I'm looing for an NA TRD tach now that I know thats the trick:)
 

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When I plugged up my scanner I noticed that my tach is actually off by almost 500 rpms by redline when I jumpered the resistor like in the post. It's only off by 100 rpm at idle though, it seems it gets worse the higher rpm. I bought a used TT tach and measured the resistor and it's a 52k resistor. I went to radioshack and paid 99 cents for a pack of 52k resistors and put that in place of the NA 33k and it works perfect. It's not off at all anymore. Hope that helps for other cheap solutions. I'm looing for an NA TRD tach now that I know thats the trick:)
thanks for the input, much appreciated. is jumping the resistor is all you need? (can you answer my question in my post above?)
 

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I completely removed the na 33k resistor, and replaced it with a 52k resistor. That's all I did and the tach is exactly correct now.
 

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I completely removed the na 33k resistor, and replaced it with a 52k resistor. That's all I did and the tach is exactly correct now.
Ok, I have done the GE to GTE conversion, please don't be a cheapskate and use a patch wire. Buy the required resistor in case you get a spike in power!

This is my NA tacho, see the blue resistor? That is all you need!!!

guys, thank you. you just gave me the info i was seeking for a long time. thanks again. will try it and let you know of the results ASAP. *thumbs up*
 
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