N/A to TT Conversion: Tach fix?

[suprakaz]

Been looking around the forums for this fix, the Tach, what needs to be done exactly, is there a write up anywhere, anyone out there get their tach to work after completing the swap?

[94mkivTT]

All you have to do is get a tach from a Turbo. The 6spd will work on an auto, but you'll lose the P N D R etc. TRD tach will work also.

[JZ1]

Depends what ECM you are using.

[Kruso]

All you have to do is get a tach from a Turbo. The 6spd will work on an auto, but you'll lose the P N D R etc. TRD tach will work also.

+1, no other work around for it.

Kruso

[KirkMKIV]

+1, no other work around for it.

Kruso

There is a "work around" but it involves more than simply swapping out the NA Tach for a TT one.

[figo]

There is a "work around" but it involves more than simply swapping out the NA Tach for a TT one.

:stupid:

[Kruso]

There is a "work around" but it involves more than simply swapping out the NA Tach for a TT one.

I'm sure there's a way of doing it but none that has been identified on the boards. I have done one on a SC300 but when it came to the MKIV, I had to swap the tach altogether.

[KirkMKIV]

I'm sure there's a way of doing it but none that has been identified on the boards.

It has been discussed many times. Search for Dakota Digital.

But like I said, it's far easier to swap out the tach to a TT as I have done so myself.

[StarletGTT]

There used to be a write up here. All you needed to do was to bridge two wires together and the stock N/A tach worked on the TT. I have tried to find that writeup but no luck. So I had to find a replacement tach for my friends swap.

On the other hand

I have a Auto TT Tach FS. LOL $50 Shipped.

[Shitzu]

Check out post #9....

http://forum.clubna-t.com/showthread.php?t=7291

[Kruso]

I'll be damned, I must have searched for this for two days straight when I was doing mine. Stand corrected...

Kruso

[Jimbow]

I dont mean to threadjack but Im doing this also. so what if you use a TT ecm, will the NA tahc work? if not what do I have to do to make the NA tach work? my car is a 6speed also.

[Shitzu]

I dont mean to threadjack but Im doing this also. so what if you use a TT ecm, will the NA tahc work? if not what do I have to do to make the NA tach work? my car is a 6speed also.


The NA tach will not work with the TT ECM, you'll have a couple of options:

Replace the NA Tach w/ a TT Tach
MSD Tach adaptor 8920
Or Try the Mod above......

[Kruso]

I dont mean to threadjack but Im doing this also. so what if you use a TT ecm, will the NA tahc work? if not what do I have to do to make the NA tach work? my car is a 6speed also.

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


The NA tach will not work with the TT ECM, you'll have a couple of options:

Replace the NA Tach w/ a TT Tach
MSD Tach adaptor 8920
Or Try the Mod above......

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.


http://i91.photobucket.com/albums/k307/captdale/100_0711.jpg

http://i91.photobucket.com/albums/k307/captdale/100_0713.jpg

[suprakaz]

^^ thanks will try that out later

[Sketch_hs]

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"

From the ignitor that's terminal 4? Bottom right?

What is the wire on the "diag connector"?? I was thinking it means DIAGNOSTIC connector under the hood? There is no black and white wire there (97 harness)

[KirkMKIV]

I think that only applies if you are using the NA harness and TT ECU.

[Sketch_hs]

Where would you hook up the wire on a 97 tt harness ? Aristo ecu :(

Damn it.

[KirkMKIV]

Where would you hook up the wire on a 97 tt harness ? Aristo ecu :(

Damn it.

I may be mistaken, but you do not need to do any wiring aside from jumping the resistor if you are running a TT ECU and Harness. The person who wrote the "tutorial" was running TT ECU on an NA harness and 2JZ-GE.

[Sketch_hs]

How does the 97+ harness get the tach signal if there is no wire?

thanks guys---

Im going to jump the tach and put the harness back to stock i guess.

So normal if someone uses a TT harness, aristo ecu and NA chassis they would just swap the tach out for a TT with no other mods to that area?

[Sketch_hs]

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...

[Kruso]

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

[Sketch_hs]

Anyone got the Aristo pinouts?

[Marmoot]

On my NA-TT, I did the 33k Resistor bypass but I didn't need to do the Igniter wiring mod.

It worked fine.

[Marmoot]

P.S.

It is 95 SZ Supra with Aristo 2JZGTE engine.

[suprakaz]

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

[boosted_b20]

i jumped the resistor on mine and it works perfectly
...thanks Kruso!

[1GStoEnvy]

great info...

[SDstreetracer]

I wonder if this resistor bypass will work on the NA TRD tach?

[cleansimplelook]

buy a dakota digital from dr tweak and ask him where to adapt it to, cluster will work 100%

[supratter]

I wonder if this resistor bypass will work on the NA TRD tach?

it should, there's nothing different from an NA tach other than a couple thousands rpm's more and a very cool logo ;)

[SDstreetracer]

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.

[dj3BOUD]

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.

[Dj6ta]

?? 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.


http://i91.photobucket.com/albums/k307/captdale/100_0711.jpg

http://i91.photobucket.com/albums/k307/captdale/100_0713.jpg

I have personally done this and it worked perfectly.

[DenverSupra]

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

[MIsupra]

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:)

[dj3BOUD]

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?)

[MIsupra]

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.

[onggie]

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!!!

http://static.zooomr.com/images/9638678_7ca2851fc9_b.jpg

[dj3BOUD]

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!!!

http://static.zooomr.com/images/9638678_7ca2851fc9_b.jpg

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*

[dj3BOUD]

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!!!

http://static.zooomr.com/images/9638678_7ca2851fc9_b.jpg

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. (btw my engine swap is a JDM on USDM car, will the fix work regardless?)

[WiLLs SuPra]

Sorry to bring this old post back up. But was wondering..I have a USDM 6-speed harness and an Aristo motor..but a N/A tach. Is ^^ this what I need done to make my tach work again? Get a 52k resistor and solder it on my N/A USDM 5-spd tach?

[Ryeno]

http://i91.photobucket.com/albums/k307/captdale/100_0711.jpg
remove the 33k one (three orange strips) and replace it with the 52k one.

I bought a 51K because that's what they had at my local electronic store. I was planning to confirm that guy once I got my engine running.

[HotSupra93]

Im doing the gte swap using aem and tt harness, do i still have to go through this ?

[Bigspoolin23]

http://i91.photobucket.com/albums/k307/captdale/100_0711.jpg
remove the 33k one (three orange strips) and replace it with the 52k one.

I bought a 51K because that's what they had at my local electronic store. I was planning to confirm that guy once I got my engine running.

Which resistor is it? The big blue one? or the small one in front or the smaller one behind it?

[Letsride]

The one to the right (small one in front of the smaller one).

[Dj6ta]

On my NA-TT, I did the 33k Resistor bypass but I didn't need to do the Igniter wiring mod.

It worked fine.

Same here.

[mysticblu999]

This helps alot

[zerofast2000]

Im doing the gte swap using aem and tt harness, do i still have to go through this ?

I'm wondering the same thing. I have a NA 5spd that I'm doing a full GTE swap and running AEM V1. Will my NA tach work or does the AEM V1 send out the same signal as the GTE ECU and still have to do the 52K resistor swap?

[Ryeno]

The stock configuration for tach on the non VVT-i engines is tach signal from the igniter so you'd need to do the resistor swap. BTW I measured it myself and got 51K, not 52k, coincidentally exactly what I bought before I even measured. I'm sure you can setup the AEM EMS to output a GE tach signal.

[zerofast2000]

Just picked up the 51k resistors today. They were only $1.50 for a 4pk at my local electronics store. Way cheaper than buying a $400 dollar TRD Tach that does the same thing as the NA one. I was wondering, is the resistor on the tach a 1/4W or a 1/2W? I didnt know which it was so I picked up both. Just wondering which one I actually need? Im guessing the 1/2W judging by the size in the posted pic.

[AE111]

I tried the 51k resistor mod but it didn't work, I was going to just jump it completely but tried a 16k instead and that worked fine, looks to read accurately. I'm a JDM 6-speed SZ-R to JDM supra TT motor, didn't think that would make a difference but maybe it does.

[kazumaTRD]

interesting information, and just wanted to check this out. found:

NA resistor color code: yellow, orange, orange = 43k
TT resistor color code : red , yellow, orange = 24k

FYI - visually inspected and confirmed with the ohm meter andthen found it to be within that range

[zerofast2000]

interesting information, and just wanted to check this out. found:

NA resistor color code: yellow, orange, orange = 43k
TT resistor color code : red , yellow, orange = 24k

FYI - visually inspected and confirmed with the ohm meter andthen found it to be within that range

My Setup:
1993 NA 5spd
2JZ-GTE Engine
'97 OBD-II US-Spec 2JZ-GTE Engine Harness
AEM V1 EMS

Tonights results:
1) I removed the stock NA tach resistor and replaced it with the 51K resistor but tach still did not work.
2) I removed the 51K and just jumped it completely with a small piece of wire. Tack appears to work correctly BUT...
I compared it to the signal my AEM is receiving. At idle it appears ok, +/-100rpm. using my 2step set for 4,000rpm, the tach and AEM read the same at 4100-4200rpm. However when i gradually climb in rpm's from idle to 2,200 rpm the Tach reads less than the AEM. at tach speed (2200rpm) my AEM reads 2,600.

From what I understand, My tach is not getting a strong enough signal. No resistor is needed. In reality, it seems like it could use even less resistance/stronger signal. But I don't know how to do that when I already jumped it, other than to boost the signal somehow. Anybody got any thoughts or opinions on this? Anyone else have this same issue on their car?

EDIT:

http://i76.photobucket.com/albums/j37/esvimonteiro/tach2.jpg
100ohm (the blue thing is a 100 ohm metal film resistor 1/4 watt) parallel resistance that will drop the tacho series resistance to close to 100ohm which gives a suitably high signal for the tacho to register. I used a piece of wire and welded it and works fine.

Just found this on Club NA-T. Anyone tried this 100ohm resistor mod?

[kazumaTRD]

had a spare NA tach....So I went to Radio shack and bought the only one closest to 24k, a 22k, replaced the 43k NA resistor and worked great. but could not compare to known source. btw, from what I remember, by jumping that NA resistor, voltage is being divided between the 43k and jumper,ohms law anyone? E=IxR

[zerofast2000]

had a spare NA tach....So I went to Radio shack and bought the only one closest to 24k, a 22k, replaced the 43k NA resistor and worked great. but could not compare to known source. btw, from what I remember, by jumping that NA resistor, voltage is being divided between the 43k and jumper,ohms law anyone? E=IxR

I had removed the stock NA resistor completely when I did the jumper mod. Im not a physics major, but just assuming that everything takes the path of least resistance, it wouldnt matter whether it had a resistor or not. Anyone with an education have some input on this? LOL