You know the kind when you press the pedal you almost go out the windscreen. What does this mean, if there is a fault where would it be located?
Maybe a dumb question but whats life without the odd dumb question 
If it’s the trl then the brakes are probably just wound on a bit to much. It’s a quick 5 minute job if you’ve got the right sized socket/spanner or if your not allowed to do your own repairs then it’s a 2 minute job for a fitter. 
Had it when I was working on agency for lafarge, phoned them just to let them know and I was gonna fix it and they were NO NO don’t touch it we will get a fitter out to you, 3 hours later he turns up I tell him what’s up 2 minutes later he was on his way. Doesn’t worry me I was getting paid by the hour 
Could also be a seized or faulty load sensing valve.
i’ve had this problem, i had an old DAF 95xf. we always pulled old trailers which was fine.
when we were taken over, we got some brand new trailers. i took one out and almost jacknifed.
i changed the ABS suzie for one with more pins than the old one. that did the trick.
I had one Tuesday Took advantage of the smoke effects from the tyres, I was all day in the London area, so it made an impact if you knew when to apply the brakes for maximum impact 
Love the smell of burning rubber.
And it was on discs too 
Sir +:
Could also be a seized or faulty load sensing valve.
+1
It’s great when reversing because when you touch the brake you see the trailer shoot up in the air as the suspension maxes out lol
I was shunting one night in McVities in Parkhead. I was moving this piece of crap trailer belonging to er… never mind there was no air in it so I bloody had to plug the lines in and when at max speed in R2 I swear I just touched the brakes and got this big almighty bang. I swear the trailer must have lifted at the back the brakes shot on so fast lol
It’s also great for drifting round roundabouts at night in the wet if you’re brave and have enough skill. Just don’t let plod see you unplug the abs suzi before hand
Oh how I miss trucking…not
Older trailer, probably load sensing valve
Newer unit -vs- older trailer, poss incompatible or faulty ABS/EBS cable
If it’s a new (2 years or less), likely to be the EBS command module (version 2). Our SDC trailer brakes turned into an on/off switch with no progression at all. Diagnosed to a faulty command module, which was on back order as so many were being replaced under warranty!
Steve-o:
It’s also great for drifting round roundabouts at night in the wet if you’re brave and have enough skill. quote]I like it
Had the same thing the other night, going round an intersection, not fast but in the wet, tapped the brake and experienced a horrible lurch and the amber ABS light came on same time. No harm done, but a ‘brown-trousered-moment’ none the less! It was my old trailer, which spends most of it’s life parked up these days now we’ve got the super new ones. I’m told that come January they’re going to get rid of it, so they won’t bother sorting out the ABS…ring a chord with anyone?