• Hi everyone, I keep reading on the manual about jumping TEN and GND before doing various adjustments/checks. What Id like to know is why must I do this? What is jumping these terminal points doing? Id like to adjust my idle as its a tad low, and I have to bridge these points, which personally I dont understand why when its just an idle adjustment.

    Please dont assume I know anything, Ive come from the bike world and while I know alot about what Im doing there, I got no clue here. Idle adjuster screws poke out of the side fairings of bikes, with no need to bridge anything, just tweak and go. Maybe its the difference between carb and FI.

  • Hi mate,
    never even heard of that before, but i did a quick google search for 'ten' and 'gnd' + mx3 and it bought up this:


    hope its usefull in some way


  • I am not 100% sure what it actually does but has helped me out a couple times on idle control

    on a MX5 I had there was a vacum pipe disconnected when i put it back on it reved all over the place then grd ten and it ran perfect after it

  • I think, and kinda logical that it resets the ECU, allows the ECU to write default values, or ignores ECU saftys.

    without a full reset (Which I think is Disconnect NEG battery, Pump Clutch)

    More thenlikly wrong tho.

  • The only thing i have used them for in the past is fault finding (pulling codes), they give you codes via the LED flashing. Not sure how it relates to setting your idle control. Have you tried putting a multimeter on your idle control to see if it has the correct voltage output?


    Sorry if you have already seen this but its very helpful.

  • When you jump TEN and GND you are putting the car in diagnostics mode.

    I believe if you adjust the idle without doing this the ECU will try and compensate for less or more air using the IAC (idle air control valve). So if you want to do it right you should jump TEN+GND and set the idle a bit lower than you want it (IIRC 650 to get 750).


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