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G4x plug-in on 04 fxt. Fault 85/86

Link G4 Plus Software Tutorial

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After installing a new link g4x in my 04 fxt(an 04 sti disguised as a Forster) I was going through all my input calibrations before initial start up so I could calibrate timing. Everything is checking out and then the last input I was calibrating was the e-throttle and TPS tables. I’m running into abit of a head scratcher.

inputs are as follows:

tps(main) - an volt 2

tps(sub) - aux 9/10

tps(sub)relay - ign 8

all my min max voltage error ranges are above and below what voltages are being registered.

im getting two fault codes, 85 and 86 which reference the aps main and sub are above or below the min max.

When I calibrate the TPS. It’s able to move the throttle body open and closed(I can hear it and I see the virtual slider moving up and down) but it seems the e-throttle won’t move with it so it fails. However if I move the pedal I’m seeing the voltage rise and fall between 1.04v and 3.94v.

Let me know what y’all think and if you need any additional information

Appreciate you


Bonus question. The e-throttle table 1, with APS% vs RPM. Is at all zeros, does this mean it will default to a linear relation ship between E-throttle position and throttle plate position? Or do I need to tell it to be open at the respectable percentage across the rpm range for every percentage cell if I want it to be linear.

I think you need to fill out the E-throttle 1 target table. I would start with just 0-100 for 0-100 APS Main % for all RPMs. This is used to limit the throttle if you want. For example, and 1000 RPM, there is probably no more air going in above about 60% throttle position, so you could map 0-100 APS % into 0-60, or peg it as 60% from 60-100% APS.

I suggest reading the help for "Electronic Throttle", and "E-Throttle First Time Setup".


-TPS (Main) and TPS (Sub) should both be AN Volt Inputs. APS (Main) and APS (Sub) should also be AN Volt Inputs.

-The Aux 9/10 is the output to the Throttle Motor.

My guess is also that you need to populate the APS vs RPM E-Throttle 1 Target table for it to work.

Thanks y’all! I’ll double check my in/outs as I did recall them from memory when I wrote this. And will fill out that table. Appreciate it!


I now have a functioning relationship between the APS and TPS. But now I'm learning about fault 77. Which points to a tracking error, looking at the voltages on AN 9/10 there is an 8.7% discrepancy at closed and a 3.6% discrepancy at open. Ive done some unplugging and replugging of the plug at the Pedal and some tugging and pushing of wires and I witness a tiny bit of fluctuation of voltage on the (main) when i do this. If there isn't some way to account for a consistent difference in the software I'm guessing ill need a new pedal? What do you think?

I would also assume this is why I'm seeing 7.4% open throttle and only 96.2% at WOT on the TPS slider even after a successful calibration. Seems odd to me that this wasn't a fault on the stock ECU which was functioning well only 4 days ago, but these things happen of course.

As always I appreciate your time and efforts giving me your opinions!


Have you done the Accelerator Position Sensor calibration? If not, that should solve error 77.

I did the calibration spanner in the tps menu and it passed but did not see one in the e-throttle config window. But I guilty of not searching for an APS config if that’s a different specific config aside from e-throttle. I’ll check er out tomorrow! Thanks so much!


Sorry for the slow reply, I dont check in here very often. FYI you will get much quicker help on the Link forum if you get stuck. It sounds like you haven't done the APS calibration. This is step 8 in the setup guide that David suggested above.

You will need to put E-throttle in setup mode to unlock the calibration tool. Then follow instructions on screen.

For sure I’m started to read all of the read me with the link software. Certainly very thorough! Thanks for all the help, I’m sure I’ll be back. Hopefully with less RYFM questions 😂


We usually reply within 12hrs (often sooner)

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