diamond white

Any ideas? 3Dr been laid up prior winter, just brought it home for the summer and the damn ABS light is.... The system was ok when last used, worked as advertised. Have parted and remade all connectors from wheel sencers and the electric pump is cycling when it should but fault still present. So where to now, im sure its only a dirty plug. Ideas welcome...

JamesH

iTrader: (21)

I had a similar prob on my Saff, turned out to be a purple relay under the passenger side dash!

cozmeister

iTrader: (1)

The pump motor relay. The green one nearby is the relay for the ABS power system. There's also an orange one in position VII in the fuse box which cuts power to the ABS system while starting the engine. It's a little unclear which cars have this orange relay - some claim it's 4x4s only, while my understanding is that it's 2wd Sierras only - mine certainly has one, and that's 2wd!

If you're hearing buzzing with the key at 'I' then the relays are probably OK.


Would you like a copy of the Ford ABS Diagnostic manual?

opposite lock

iTrader: (3)

mine was always good then suffered this problem too, for 9 months and 3k tut tut (dont tell anyone) light always on, coming back from blackpool msd , last 80 miles or so me pal drove , we then noticed the light was gone, abs working, not sure if msd fixed it without saying (im sure they would of) or the car liked my friend lolol pmsl . Also found a rear number plate light back in action too.

diamond white

Thanx guys, will look at the relay's and i'll get some electrical cleaner and retrace my steps so far, im back on shift till the weekend before i can get my mits dirty, but will get back to you all, so fingers crossed!
Cosmeister if the problem persists then will take you up on your offer of the ABS Bible, speak soon...

ASHCOSSIE

mine has a probem where the light comes on as should and goes off but occasionly flickers on, and even with the light off it still locks up wheels

t4 and greys

iTrader: (5)

also worth getting a wire brush on the grooves for the abs on the driveshafts
they usually rust over and the sensor wont pick up the grooves !!
worked on mine anyway

Glenn_

iTrader: (1)

when the car is running but stood still does lie light go out or is it just on all the time.

diamond white

Glenny Boy... In answer to your question. ignition on n start, ABS lights on till pressure built up in accumulator, then lights go out, approx 10 secs, well within spec. If pressure present in accumulator, ABS lights will stay on until the lights cluster on centre console (above clock etc) have done their bite check. The problem arises when you drive off and will stay on till ignition switched off. Abit long winded i know but thats the problem blow by blow...

cozmeister

iTrader: (1)

The general rule of thumb is that if the yellow light's off until you reach ~15kph, it'll be a wheel sensor/toning ring (teeth) fault.

Start with basics first: there are two fuses - a 30A one attached to the purple relay (pump motor) and a 20A one attached to the green relay (ABS system). If either is popped, the system won't work. Both brake warning lights (red and yellow) will be lit.

If the yellow light's on before you start moving, it's either a wheel sensor wiring fault (ie, shorted/broken coaxial cable or disconnected), OR, one of the level/pressure sensors is reporting a problem. The valve blocks are pretty reliable, so it's rarely that. If the pump motor's not working, the pressure will be low, which will bring the yellow light on, shortly followed by the red one.

A faulty or unpowered ABS ECU can also cause the yellow light to stay on. The hydraulic pump is not controlled by the ECU - its relay is energised by the pressure switch in the hydraulic unit. This is so that full braking power will still be available but without anti-lock. If you have a mate nearby, get him to pop over and swap ECUs - you'll soon see if it's knackered.

On occasion, flushing clean brake fluid through the system can sort it out if it's a piece of grot or loose sediment gumming it up - but most problems with the Sierra ABS are electrical to some degree.

RichieST

iTrader: (2)

I would try cleaning up the sensors and toothed rings first, chances are they've got a bit rusty where its been sat over the winter.

diamond white

Thanx guys.... guess who's going to be a busy little bee. Will go through it all as sugested, when im on my days off. Will report back if im making honey, or whining if not....

Glenn_

iTrader: (1)

As already said sounds like a pick up ring covered in grease or shit lol.I wouldnt even try to attempt to get the sensors out of the hubs.I would just remove the drive shafts and front hubs to clean the pick up rings.My abs light was on a few weeks ago.I knew it was the osf wheel.The sensor came out ok cause ive had it out many a time.


There was a bit of grease inbetween the teeth.I stuck a small screw driver in the abs sensor hole and cleaned the gaps between the teeth.It took some doing but its sorted now.