ABS warning light, Renault Master van

Should have said, it's 120k miles but generally in pretty good condition for the age.

First check would be that it has sufficient brake fluid and working brake lights.

Great, thanks. Brake fluid level was OK, checked the lights the day before but will have another look now, and also "wiggle" the electrical connector on top of reservoir.

Low brake light is going to put the general brake light on, probably same one as handbrake, rather than ABS.

I'd start by investigating whether a wheel sensor cable's failed, probably a front.

Must admit that was my first thought too. Presumably if my guy hooks up the laptop to it he'll get more information. The fault appeared after getting the front end bogged down in a muddy hollow, but I'd have thought not deep enough to foul anything. I got a landy to tow me out before letting it dig in deep.

Thanks all for the comments. Seeing him in the pub at 6.

Aha! The drip-drip-drip of pertinent information...

Did the light come on with ignition, or only when you started to move?

If the latter, then it's possible that the toothed ring is clagged with mud. If the former, then it's almost certainly a sensor or cable got clobbered or snagged.

Shouldn't be difficult to diagnose. Pull the wheels off and look.

Yes, sorry about that. I *think* it came on after I started to move. But as I say, I'd be slightly surprised at a mechanical cause, the mud was no more than half way up to the wheel rims. It turned out that there was a very sharp transition between MOT type hard standing and topsoil and I

But I will whip the wheels off when I get a chance. (It's parked up in a stable yard where maintenance is not particularly convenient).

But thanks again for the suggestions.

I wouldn't have any qualms about driving it in the interim. If the ABS is AWOL, you just won't get the ABS kicking in, it'll just lock up instead.

How often have you braked your horsebox so hard the ABS kicks in, up to now?

Certainly never with animals on board! In all my driving experience, I have only had one instance when I was glad to have it, and that was in a hire car about 20 years ago. Some idiot suddenly pulled into the fast lane just as I was passing, so offside wheels were locking as I pulled off the carriageway to within a couple of inches of the central crash barrier. He noticed me just as I got alongside and I just squeezed past without touching anything.

Too cold to grovel around looking this morning, but when I switched on the ignition the ABS light came on, then went out, but leaving the "service" light on. I then pulled backwards and forwards a few yards, and the service light cleared. Will see what happens in a 30 mile run on Saturday.

With the new information about the mud. Quite a few cars will throw up an abs fault light if you get some wheels turning without the others, so maybe if you had wheelspin in the mud, it may have confused the system temporarily, a few reboots later it has cleared itself, fingers crossed.

I once managed a 6 or 8 wheeled lock up in a Disco towing a horsebox. 4 on the (empty and relatively light) box and a good couple or so on the Disco (which had had the ABS removed.)

I don't understand people who will pull out in front of something that could weight in at anything up to about 6.5 tonnes.

Some systems will note a spinning wheel as a fault if it's for any length of time and take a while to clear it again. Seen this with a Focus with one wheel jacked off the ground.

It's either "Oooh, that looks slow, I don't want to be stuck behind that" or " " (since they didn't even bother looking).

Useful theory. There will have been a bit of wheelspin, but after that I had a 30 mile drive on normal roads and it was still present at the end. Still, perhaps it does need a full re-boot!

The temptation to keep going is always strong. And why is it that people who nip out in front never actually put their foot down to any degree?!!