the GS you mention was a 91 model, correct? So it should have the 3 flasher keys, right?
If yes: how did you turn off the flashers? I emailed with the m-unit support, because I missed the input for the "flasher off" key. In all douments or wiring diagrams they only mention "left on key" and "right on key", but no "both off". They replied "there is none" and pointed me towards that several "auto off" modes you can program. But that's not what I like.
I replied once again with the specific question - radio silence until now.