I have noticed on a number of the many occasions when a left ■■■■■■ moves on by that the ABS light is glowing on the dash, particularly the Scania’s (cos its easy to see) 
Would this be deemed as a defect by our friends at VOSA? or is this just maybe down to the trailer specs?
Woody,IT means in most cases that the system is working
or that the tactor unit has ABS but the trailer is not fitted with
such a brake system.
Or the fuse is pulled and the limiter off 
Trailer ABS light glowing could mean faulty ABS. Other possibility is that trailer has perfectly well working ABS brakes, but trucks ABS-system is only thinking them to be out of order. I don’t know what causes latter behavior, but it isn’t anything unusual.
I’ve heard something about different aged ABS systems having different number of conducting wires (5 and 7?) which makes light to show up in newer trucks towing trailer with older ABS system. I don’t know if there’s any truth in this, but you can always do “visual” check when coupling. Couple seconds after ABS cord is plugged there should come clear “click” noise from every axel having ABS detector. I don’t know for sure if this always means ABS is working (it usually means), but if you don’t hear any click’s then it’s sure something is wrong. With artic an running engine might prevent hearing of these sound, so checking this way might require turning engine off and leaving keys to “ignition position”.
I used to have loads of trouble with the ABS light on my Scania, seems it didn’t like older trailers.
I thought that it was a flashing Suspension warning light that meant the fuse was out… 
Kyrbo you are right there are different pin set ups on ABS.
My volvo and any other i have driven has always at some point dissagreed with the trailer and abs light has come on
Discopete:
Or the fuse is pulled and the limiter off
You know too much
Lovlyperson:
Discopete:
Or the fuse is pulled and the limiter off
I’m paid to know too much!
i always thought that pulling the fuse stopped the indicators working
having never pulled one i’m not sure
where i work they are painted in and checked weekly by the yard spy
If the wrong fuse is out it stops the charging circuit… not good !!! 
I got pulled in at Wetherby a couple of years ago by Vosa, when the examiner checked the dash he saw the ABS light on and said it was a fault, I pointed out that it always came on when it was stationary and the ignition had been off.
It was a Merc Powerliner, he was determined to write a PG9 for it as faulty so I told him to wait a few secs whilst I pulled forward, the first thing he said after that in a loud voice was DO NOT PULL OUT !!! he must of thought I was going to do a runner but just moving the truck 10ft saw the light go out and he was not too happy as I was proved right
Scanias are the worst for matching up with trailers, you can guarantee you always get a light on the dash illuminating atsome point during the week with ABS 1 showing as a fault
Apparantly though it is an offence to drive a truck with an ABS warning light lit up.
brit pete:
Woody,IT means in most cases that the system is workingor that the tactor unit has ABS but the trailer is not fitted with
such a brake system.
If it’s lit, it ain’t working. Sometimes it’s an incompatibility between the system on the unit and the system on the trailer.
Conor:
brit pete:
Woody,IT means in most cases that the system is workingor that the tactor unit has ABS but the trailer is not fitted with
such a brake system.
If it’s lit, it ain’t working. Sometimes it’s an incompatibility between the system on the unit and the system on the trailer.
Not true.
ABS light can come up by “incompatibility” between truck and trailers systems, but it doesn’t automatically mean malfunctioning.
I’ve been couple times at “slippery condition track” (oil on steel plates) with a -02 model Scanny which had trailers ABS light lit all the time. We were just told to ignore that light. Despite the light, ABS were working perfectly as A-frame trailer did stay in straight line, no matter how hard you were braking. That definately isn’t the case if it would’ve meant ABS not working like Conor stated.
Another case is with -05 model FH12 which also thought trailer has malfunctioning ABS. When asked from Volvo garage they just told to ignore it, as they can’t do anything to stop it coming up. They said it’s just incompatibility issue which makes trucks computer to think trailers ABS isn’t working while in reality trailers ABS system still works just like it should.
We regularly have an ABS lamp showing while the ABS is working perfectly well, it is due to incompatibility most of the time.
The trailer I had this week though didnt have ABS, it had leaf springs and a cable operated handbrake. It followed like a moslems wife and could carry 28 tonne.
Woody, dont be so nosey, I will hide my ABS light with a ■■■ packet 
All said and done, how would one convince our VOSA brethren that together with other incompatibilities on our trucks and trailers that “all is well” despite the trucks management telling them otherwise. I can well imagine the lively debates held at their various check points, which now seem to be an all too common sight around the country. Or, does one presume the officers “understand” our vehicles as well as we do? 
Woody:
All said and done, how would one convince our VOSA brethren that together with other incompatibilities on our trucks and trailers that “all is well” despite the trucks management telling them otherwise. I can well imagine the lively debates held at their various check points, which now seem to be an all too common sight around the country. Or, does one presume the officers “understand” our vehicles as well as we do?
I know from experience that you can’t / they don’t 
I got a delayed PG9 for exactly this fault. (It was deleted from my companies records, when it was proved not to be an ABS fault)
It’s an incompatibility fault rather than a faulty ABS. It can be cured by fitting a jumper wire between the two correct pins at the back of the ABS socket on the unit or trailer. Unfortunately I don’t know which pins are the correct ones. Doing it yourself wouldn’t be a good idea anyway (any problems would then be blamed on you doing a home wiring job). You should report the ABS warning light as a defect on the unit - relating to the trailer, to your tm. Your tm should then get the workshop to fit the jumper wire.
The incompatibility is only on older trailers with one make of ABS fitted, again I can’t remember which make. The make of ABS fitted to Scania tractor units in particular, is especially bad for showing the yellow warning light.
This is a well known and documented fault. If you like you could probably find it on the net. I doubt it’ll be easy though.
(If you find it, give us a link to the site, I’m sure that several people might like to download a document to carry, just in case )