What does this button do?
Were the last words said on the space shuttle challenger!
Steve-o:
It’s a (O) with a sideways 8 in it… i this some sort of transmission brake in addition to the Jake? I drive an ERF ECT. 16 speed man if that makes any difference. Thanks
Should have made this a poll question…just to see how many really useful answers you would have got to all the daft ones 
Personally I think it`s something to do with chameleon mode…it allows you to change into an MAN and back to an ERF at will…helps to confuse VOSA Patrols.
Sorry only drive Volvos and Mercs
isnt it the button you press before taking a quick nap? or making a brew on the motorway 
your all wrong
warning if you press this button it causes several other warning lights to flash up in a random mode when ever it feels like
its a money making scheme by the makers to make sure it has more time in the workshop than on the road 
Leave it alone, you will wear it out, then it will cost more money to replace.
Leave it alone, you will wear it out, then it will cost more money to replace.
Never a truer word said in jest but whatever you do …
…DONT PRESS THE RED BUTTON!
I’ve checked the ERF ECT manual I’ve got and can’t find any mention of a button like you describe.
Although I’m sure I recall seeing something similar myself…perhaps on an older DAF 85, I’m trying to rack my brains but I can’t remember at all what it was for.
Its slightly worrying though isn’t it, thread has had over 1129 views by “professional drivers” and not one of us can remember what the button does and its not like its an uncommon vehicle!
Alex
The only button that i can think of that may be similar is a trailing axle or lift axle button.
like o—oo
or it is maybe a booster button 
I think the last ERF I drove was a B Series with a 13 speed box
Quinny:
03 plate TGA ERF/MAN.If the switch you describing is what I think it is,iirc,it’s an exhaust brake switch,that when you have it in the on position,activates the exhaust brake,when you take your foot off the throttle.
Ken.
This is what I reckon it is too.
I’ve been lucky enough not to drive one for a few years though, so…
is it a 6x2 without a lift axle, if yes its the air dump button
Can’t believe this thread got brought back from the dead… It was so when you take your foot off the (try to) go pedal the exhaust brake would go on.