ABS and Traction Control lights on when engine cold

sassy_one

Hi

I have had a problem now for a few months, whereby my car's ABS and Traction control lights will come on prior to start up and stay on once the engine has started.

I have a Ford Mondeo 2.5 V6.

I have now managed to work something out and these are my findings:

The ABS and Traction control lights come on when the car is first used in that day, after 5-10 miles they will go out after the brakes have got warm/hot.

I have jetted the inside of the wheels (sensor, housing and brake drum) will a high pressure jet wash and found that after you have done this and the discs are cold again they come back on.

I have cleaned all the wheels and jetted them so doubtful it maybe a sensor down, it will stay off throughout driving range once hot until left over night again.

What could these signs be/mean?

The brakes are working fine and DO NOT lock up on an emergency brake and the brake fluid is clean and the correct level, the servo does NOT get hot either and there are no drips off any of the brake lines

I have also plugged a faults code reader in and even when the light is on, the fault code reader is telling me 'No fault codes found' and I have also kept the code reader plugged in throughout driving one day, which still showed no codes.

I'm at a loss now as I feel there's no more I personally can try, any ideals would be good.

Thanks

KillerWatt

Metal expands when hot, and both the ABS speed sensor and reluctor are made of metal.

As the fault is only present when cold, I'd be looking at an air gap fault to start with (especially as something as simple as a layer of brake dust can cause the problem you describe).

sassy_one

Thank you KillerWatt

I'm hoping for a sensor problem as don't fancy spending £££ on modules etc :eek:

I will take the tyres off during the week (good fun, not!) and have a poke around and see what I can see.

I will post my findings, if anything

johnnyroper

sassy-one wrote: »

Thank you KillerWatt

I'm hoping for a sensor problem as don't fancy spending £££ on modules etc :eek:

I will take the tyres off during the week (good fun, not!) and have a poke around and see what I can see.

I will post my findings, if anything

when you take wheels off have a check of the speed sensor resistence at each wheel.you should be looking at 0.9-1.1kohm for a good sensor.also make sure the reluctor rings are not corroded.

sassy_one

UPDATE GUYS


I have today had my car in for servicing and it is a sensor that is on its way out, so having to get a new one and all should be fine.

I feel lucky not to be having to pull out for modules etc.

Are the sensors easy to get out?
As I'm thinking of fitting it myself, and before anyone says, the screw isn't stuck as garage tried taking it out and came out fine, I know where the plugging goes too, just want someone to confirm its a simple job, and I don't have to remove any hub or anything (It's a front sensor, Ford Mondeo ST)