davy 6457

ok my abs has been giving me bother for ages and now its gone and learned another new trick,when i switch the ignition on the abs light comes on and then goes out as it should do! then when i start the car the light comes back on again and doesnt go out,any ideas on what has decided to play up now?

cozmeister

iTrader: (1)

1: Check your brake fluid level after the pump's primed the system. Should be on MAX when primed.
2: A wheel sensor fault will only show up if a sensor's disconnected, broken or after you start moving.
3: Do the brakes work normally with a good amount of assistance, except without anti-lock?

If the yellow light stays on after you start the engine, but is off before hand, the orange relay (VII) in the fuse box on a 2wd may be sticking. I believe this is an interrupt for when the starter's engaged. 4x4's have this relay built into the ECU, which is why the ABS ECUs can't be mixed and matched. If yours is a 4x4, see if you can borrow a 4x4 ABS ECU from someone to test that. The orange relay I think is still available from Ford.

davy 6457

well mines a 4x4 cossie but it still has the orange relay in the fuse box no.7. have tried another abs ecu from a xr4x4 cos there part numbers are the same but this made no difference,think i'll try changing the orange relay and if that fails then check the sensors

tabetha

I've had this once, was on for 5 miles, stopped depressurised system by repeatedly pressing pedal, turned key again still on, started up and went off then been fine ever since.
I still had perfect pedal/pressure all the time whilst light was on.
tabetha

davy 6457

ok changed the orange relay today from a 4x4 which the abs is working fine on made no difference also checked all the sensors and there all reading basiclly the same. what i did find out though was that if you disconnect the orange relay or the abs ecu and then reconnect them the abs light goes out and the abs works fine. of course this works fine until you have to stop and start the car again. oh and fluid levels are fine as is pedal pressure

cozmeister

iTrader: (1)

This means it's definitely electrical

There's two other relays that the ABS system uses, and it's more likely one than the other. There's a green one and a purple one under the passenger side of the dash. The purple one has a 30 amp fuse attached to it and the other has a 20 amp fuse attached to it - the 20 amp one is connected to a short green relay. swap that out and see what happens

davy 6457

ok lads put the thinking caps on!! ok i have checked all the wheel senors,replaced the orange relay in the fusebox,the main relay at the glove box changed the abs ecu and checked all earths and power supplys at the ecu according to cozmeister's abs diagrams and can find nothing wrong. so why oh why is the light still coming on and staying on when i start the thing??? any suggestions welcome no matter how random

cozmeister

iTrader: (1)

Something's being interrupted or shorted when you start it then. I'm convinced of that. If you were a bit nearer I'd pop over

Start it, yellow light stays on, despite going out before you started it. As it seems linked to the engine running (or at least starting, can you check the voltages etc still OK while it's running? Disconnect the ABS ECU and check for power, earths, wheel sensors, fluid level switch continuity at the multiplug.

Glenn_

iTrader: (1)

Nightmare mate hope you get it sorted.Ive got a fault on my abs but i havent had chance to look at it.

davy 6457

yeah checked all the earths and lives when running and during starting but nothing disappears or you dont get any low readings

Tony Rs

iTrader: (9)

Abs on the cossies is a pain my mates sapph 4x4 is playing up aswell! when hes slowing down almost stopping the abs kicks in and then stops him this happens every single time does anyone have any ideas too hope you get your problem sorted mate

Tony

tabetha

BIG TONY RS, try cleaning the sensor rings.
tabetha

cozmeister

iTrader: (1)

Agreed...the system shouldn't be able to activate at speeds below 5 or 10 miles per hour. If it is, the wheel sensors are feeding duff information to the ECU.


From what you describe davy, it really does sound like something's shorting or sticking.

Tony Rs

iTrader: (9)

Nice one guys

davy 6457

ok small bit of progress found out that the signal from pin 8 on the ecu is getting inturupted by something when you start,hense it doesnt take the earth away in the main relay to put the light out.therefore when it does that pins 3,20 dont get their live feed.funny enough though the system worked fine for 3 starts in a row then went back to arsein about

cozmeister

iTrader: (1)

Pin 8 switches on the main relay Which relays did you say you changed? The orange one and the green one? I think the green one's playing up I got one from Ford last year - Ł9

Glenn_

iTrader: (1)

Mine does exactly the same thing.I think i might have a cracked or worn pick up ring on my drive shaft.It has only ever done it since i changed the osf hub.Ive got a second hand abs sensor but i carnt see it being the sensor,but you never know.

Tony Rs

iTrader: (9)

Funilly enough his sapph is white too

Glenn_

iTrader: (1)

Ha ha ha thats mad.

davy 6457

yeah changed both green and orange got a trouble shooting guide from ford the other day so gonna go through it on sat see if it shows up any problems