If we look at the voltage and resistance readings we can predict what the ECU is looking at. With a basic circuit consisting of two resistors in series, we can take a look at how it works. Look at the Diagram in figure 1. We have an unknown that we can calculate using the electronic formula called Ohms Law. Here is a link to an
ohms law chart.
The three things we are concerned with is Current (I), Voltage (E), and Resistance ®. Current is the unknown. Let’s look at 3rd gear. V = 3.03 volts. R= 1500 Ù. Using the formula I=V/R 3.03/1500 = .00202 amps (or 2.02 milliamps). Glancing at the other gears we see that as resistance goes up the amount of voltage dropped across the resistor goes up. Looking at the formula, current will go down as well. Because we also checked it with an open circuit. (Neutral with infinite or maximum resistance) We can see our source voltage. 5.06 volts. 5 Volts is a very common voltage to using in logic circuits. Computers for example use 5 and 12 volts, with 12 volts usually reserved for fans and drive motors. The 5 volts source.
Because we only have two resistors in series and we know the source voltage is 5.06 volts, we can calculate more of the unknown to confirm. The two resistors in series have to drop a total of the voltage applied. If you put two 1.5kÙ resistors in series, you would measure 2.53 volts in the middle. Each resistor would drop 2.53 volts. So we dropped 3.03 volts on R2 in the GPS. The remaining voltage dropped in R1 is 2.03 volts.
Now, flip the Ohm law calculator and we can calculate the resistance of R1 R=2.03/.002.02. 1004.95Ù or 1kÙ .
So can we consistently come up with the same results, know that R1 is not going to change. Let’s calculate all of them to see what we get.
Now this is a little bit of a spread from the 1000Ù Let’s say user error on the initial readings, some charge/discharge time of any filter capacitors in the circuit etc. I can bump the source voltage from 5.06 to 5.08 and it will tighten up the R1 calculations quite a bit.
So, if we want the Hayabusa to think it is in 3rd gear all the time, I can cut the pink wire and connect a 1.5KÙ resistor from the pink wire going to the ECU and to the ground (black wire) If I want it to think it is in 5th gear, put in a 6.8KÙ resistor.
This is what a “simple†TRE is doing. The ECU then responds as if it is in 5th gear at all times. It does not go to backup mode, it just responds with the 5th gear settings for timing and fuel.
From what I can tell, if we disconnect the GPS Sensor cable we will lose the ability to put the sidestand down while allowing the engine to run. The voltage will go to 5. volts. Documentation is slim on this. One of two things will happen
1) Throw a c31 code and the ECU will go to the 6th Gear position.
2) Act like it is in 6th gear because the voltage window is still near the window. Of the 6th gear.
RPM will be limited to 10,200 regardless of the gear selected. JC says he has verified it is limited to 10,200. I don’t remember him saying if he got a code.
) Bingo, Code 31. Thank you, PROFESSOR! Locked 6 is the dash warning for code 31. 
