Fixing Trimble EZ Guide Plus “Low Accuracy No Corrections” in 2021

The Trimble EZ Guide Plus was our farm’s first entrance to precision guidance in the mid-2000s. While we’ve since moved several tractors to a GreenStar autosteer system, the lightbars have stuck around for spraying and some odd tillage for their simplicity and affordability.

The last few years, keeping these running has felt like a stubborn insubordination to obsolescence as dealers and neighbors tease us for using such old guidance; but here we are, adjusting satellites and finding some runway to squeeze a bit more life out of what we have.


The scope of this guide is pretty narrow: we had one lightbar with working corrections, one without. I changed all the corrections to match the working one and that fixed the issue. So this is a recipe that I superstitiously follow without fully understanding the theory of specific satellites. For example, you probably don’t need to worry about MSAS (looks to be a Japanese corrections network) but who I am to question success?

Our equipment:

  • EZ Guide Plus
  • v4.11
    • I’m told this is the last version made for these
  • Hurricane L1 Antenna


  1. Navigate to Config menu > GPS > Corrections > Edit
    • You can get to the Config menu by scrolling all the way down on the icons along the right side of the run screen. It’s a wrench icon.
  2. You should see Edit WAAS, Edit EGNOS, etc. You’ll need to enter each of these pages and set them to the following values.
    • In each of these pages, scrolling up or down will change the value in the dropdown, pressing OK will advance you down the list.
  3. Edit WAAS
    • PRN-122: Off
    • POR: Off
    • PRN-125: Off
    • PRN-138: On
  4. Edit EGNOS
    • AOR-E: Heed Hlth
    • IOR: Off
    • IOR-W: Heed Hlth
    • ARTEMIS: Off
  5. Edit MSAS
    • MTSAT-1: Ignore Hlth
    • MTSAT-2: Ignore Hlth
  6. Edit Other
    • (everything should be off)

Back up and out of the menu, and see what happens. ¯\_(ツ)_/¯

Best of luck!

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