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I did my ge auto to aristo gte with usdm auto swap using an aem v1 and the tach didnt work, I got the aem v2 and the tach still doesnt work, does anyone know what resistor I need to buy? Seems like everyone is trying different resistors and nothing is guaranteed to work.
 

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so does using the jumper really work? i've seen in this thread, a little bit of yes's and no's. would it just be less of a hassle to just buy a six tach? & if so, does anything have to be done to that tach? or can i just put it in, and be done with it? Any helps appreciated.
 

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If you just jump it with a wire your RPMs will read over 500rpm wrong at redline. I soldered in a 16k resistor over top or the existing one and redline and idle RPM indications on the tach look spot on.

Other people have removed the existing resistor and replaced it with a 52k resistor and this worked also. (I tried soldering a 52k resistor overtop at first but got no reading on the tacho, not sure if I made a mistake but when I tried a 16k it worked first time.)
 

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Raising the BAR
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Jumper wire worked on mine until I put in a 1ZZ coil setup
 

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Stock Twins King
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Ishii and I are trying to get to the bottom of this issue. There are too many "works" and "Doesn't work" responses. I have 3 tachs and last night we tried many different resistors and jumpers. Nothing worked. I have lots of test equipment.

What I am not sure of is whether any of the tachs I have are really NA or TT. I suspect one is a NA just because there are several resistors on the board that are different to the others. There is really no part # other than the I/C has a different PN. But no Toyota # that can show for sure if it is a NA or not.

What would be awesome, is if anyone has NA tach laying around where they can take a real good detail shot of the board. Then I can compare the layout and IC # on it.

If there is a way to definitively do a "how-to" knowing it is the correct way, I can do this.

So basically, the NA reads the tach signal off the igniter directly, or high voltage. The TT reads it from the ECU which is a lower level voltage signal. Hence why resistors appear to work for some. So the NA tach might have a larger resistor, like the 43K whereas the TT has like a 23k. Jumping it makes no sense at all. And probably would lead to premature tach failure.

I know I can make it work NP with a $90 Dakota Digital interface, but I want to see if I can do it with resistance changes.

So ya, a picture of the NA tach board would be awesome.

Stu
 

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The Great Kruso
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Stu, I was on top of this back when I did the tach fix on the two Supras and the SC I performed the fix on. I've forgotten quite a bit of this since then but I do remember having walked away from it with nothing left to mystery. The engine harness was another variable that changed how all this worked out. What harness are you using on this car?
 

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BoostAddict4Life
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i still never got my aem v1 to output a tach signal from the ls7 point and the tach jumpered. my tach just sits dead after my lq9 coil swap.
 

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Stock Twins King
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Stu, I was on top of this back when I did the tach fix on the two Supras and the SC I performed the fix on. I've forgotten quite a bit of this since then but I do remember having walked away from it with nothing left to mystery. The engine harness was another variable that changed how all this worked out. What harness are you using on this car?
This all started a few years ago when I was doing retro's on the clusters. I would go to put the faces back on and attempt to calibrate them. I thought I was getting tachs that were broken cause I couldn't calibrate them. So on my dollar, I replaced them. Fast forward 2 years later, I dug these old tachs out and ran them with a Dakota Digital converter. All 3 work perfectly as NA tachs. So what I thought were bad tachs ended up being (probably) a NA-T conversion car and they never told me. So 3 people got a sweet deal!

But my assumption was these were all TT harnesses, but now I am not sure. As far as converting a NA tach to work on a TT car, I have yet to find away to do this. Other than buying a Dakota Digital converter for $80, then your golden. Toyota has totally different guts between these 2 tachs as I have studied them enough that adding/deleting a resistor wouldn't do squat for converting.
 

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Well, all I know is my LS7 pin in my AEM v2 is my tach output, and I did the jumper wire on the back of the tach. It works fine for me. I dont know if the tach is getting the signal from my LS7 output, because I am running LQ9 coils.
 

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Stock Twins King
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Well, all I know is my LS7 pin in my AEM v2 is my tach output, and I did the jumper wire on the back of the tach. It works fine for me. I dont know if the tach is getting the signal from my LS7 output, because I am running LQ9 coils.
Well then i suspect the AEM is doing the coil conversion (Hi-Output) for you. Which could even mean you might not even need to have jumper-ed it. Unless you tried, and it didn't work.
 

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You know I didnt try. Ill make it a point this weekend to remove the jumper and see what effect that has on my tach. I dont have any awesome equipment to measure, but hopefully my findings can help.
 

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Discussion Starter #80
This definitely worked. I went from a stock 95 N/A manual setup to basically a stock TT swap using the w58 still, all using stock ECU's. I also later swapped to AEM v2 and v160 and it still works.
 
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