Link G4+ Fury Standalone: R32 GT-R Attesa TPS Signal

[JediJams]

Hello,

I am currently planning out a patch harness for my Link G4+ Fury to my R32 GTR. One of the last things I'm trying to figure out is how to provide the proper TPS signal to the Attessa unit.

I have a few questions regarding this topic to help complete my patch harness, and to have a better overall understanding of the system in general. I have searched the forums and found that one solution is to use an adapter from Haltech (HT-038001) to send the proper signal to the Attesa ECU. However, this adapter is designed for an R34 GTR which requires a 1:1 scaled TPS output whereas the R32 GTR uses a ratio of 2:3.

Will there be any issues using a R34 1:1 scaled TPS output adapter for an R32 GTR ?

If there are no issues, what is the actual effect of having different scaling ratios?

Another question I have just out of curiosity is what this TPS scaling device actually does to the signal. 

According to this diagram from the wiring instruction for the Haltech TPS adapter, the OEM TPS signal (I believe it's Pin 38) is simply split and sent to the adapter for scaling, and scaled output is then sent to the Attesa ECU via Pin 56. However if the scaling ratio is 1:1, I am not understanding what this adapter is actually doing. Is it converting the signal from digital to analogue? I thought the TPS signal was analogue to begin with. Please correct me if I am wrong. This leads me to my next question:

What is the reason we can't just run the OEM TPS signal Pin 38 straight to Pin 56?
Could I just T the Pin 38 wire and run one wire to the Link, and the other straight to Pin 56?

I apologize in advance for any obvious errors in my understanding as I have pretty much learned everything I know about wiring (which isn't much) in the past week. I would really appreciate any corrections to any errors I have made.

Thank you.

[Vaughan]

1 hour ago, JediJams said:

However if the scaling ratio is 1:1, I am not understanding what this adapter is actually doing

1 hour ago, JediJams said:

What is the reason we can't just run the OEM TPS signal Pin 38 straight to Pin 56?

It's a buffer so that the input impedance of the attessa unit doesn't affect the voltage of the signal that the ECU sees. It is possible to make a small circuit using an op amp to do this job.

1 hour ago, JediJams said:

Will there be any issues using a R34 1:1 scaled TPS output adapter for an R32 GTR

If possible test what the ratio is on your factory ECU, my RB25de Stagea came back as 1:1.

[JediJams]

Hi Vaughan,

Thank you for clarifying the function of the adapter.

As for the scale ratio on my factory ECU, the ratio is 2:3. This means that the R32 Attesa unit receives a lower TPS voltage when compared to a R34 Attesa unit.

If I use the R34 1:1 scaled adapter on my R32, my R32 Attesa unit will see the higher 1:1 TPS voltage rather than the reduced 2:3 output from the factory ECU. However the Attesa system cannot send more than 50% of total torque to the front wheels so I'm assuming that this will just cause torque to be sent to the front wheels more frequently?

My major concern is causing damage to the system. As long as using the 1:1 signal doesn't fry something or cause greatly accelerated wear to any of the mechanical components, I'm happy.

[Vaughan]

I don't expect it to fry anything but if you do see a voltage of greater than the supposed range you may get the 4wd light on.

I used an NGTT plugin on my car which doesn't have the 4wd buffer circuit on it and so had to do something custom for the tps output buffer. I would have to look at it again to remember exactly how I did it but I used a GP PWM on a spare Aux output to create what was effectively a voltage that I could control the level of. I cannot remember if I added a pullup and I think I did do some kind of low pass filter. When I was configuring this I did regularly get the pwm wrong as the attessa unit had some kind of internal pulldown which I didn't know the value of so it was a combination of trial and error, the important thing to take away from this though was that I didn't manage to fry the attessa unit despite putting incorrect voltages into it so I believe it is reasonably resilient.

[JediJams]

I was able to find some information regarding using an AUX output and some circuitry to send TPS data to the Attesa unit as you mentioned. I will look into it further and decide whether to go that route or to just try the R34 TPS adapter and see what happens. Good to hear that the Attesa controller is seemingly robust. Thank you for your help!