I'm having issues with the ABS system on my Focus.

I had issues with the light coming on about 4 weeks ago, and put it into my Ford Dealership who linked the car up to the IDS system and it was diagnosed as front wheel sensors.

These were replaced and the system bled via the IDS system and the light issue was sorted.

However, I now have the symptoms of the ABS pump activates each time I press the brake pedal. Even under light braking the pump will operate. The ABS light remains out, and no fault codes are stored.

Today I thought it might be the brake light switch so replaced that, and I also disconnected both fuse boxes and the ABS pump quad lock connector in case there was moisture or corrosion in the connectors, but the issue remains.

Have any of you guys heard of or experienced this issue?

Why should the ABS pump think a wheel is locking when it's not?

What else could I try?

Any help would be appreciated.

Brian.

When you say the pump is activating you mean the ABS is kicking in as soon as you put the brakes on?

Could be that the car is seeing difference in readings from one or more sensors so as soon as you brake the system thinks you've locked a wheel. Don't know if any self tests would throw the ABS light on from this before you'd get as far as putting the brakes on?

With you having the wheel speed sensors replaced I'd have another look at them in case one of them isn't fully seated or there's an issue with the wiring perhaps.

Might be harder to check but may be something amiss with the ring which actually triggers the sensor, also believe that if a wheel bearing is on it's way out that can throw up ABS faults too.

Yes, as soon as the brakes are applied, even a little the abs kick in with the pedal pulsing and the pump operating.

I will recheck sensors again but the dealer said they were all ok on the IDS system.

I understand that my car, a Mk 2.5 uses a magnetic ring instead of a toothed ring. I did check the wheel bearings but they were smooth with no play, so thought that they couldn't be the issue. ..could they?

Sounds like a wheel bearing to me. Take it back to ford dealer and tell them they aint fixed it, they will see which wheel is playing up on dattalogger on ids.

My Mk2 1.8 TDCI was doing this, just the slightest amount of brake applied & it felt like the ABS was kicking in. I know you've had the speed sensor replaced but my issue was caused BY the speed sensor being knackered (it wasn't sending any data to the ECU). A replacement sensor fixed it & it's been perfect. I would take it back to whoever did the speed sensor & get them to plug in the diagnostics machine & check the speed sensors are all sending data & also data that is within specs.

(I found the ABS system will err on the side of caution & kick in all the time if it's not happy with the speed sensor readings).

I've not had the speed sensor replaced, only the wheel sensors.

Is the speed sensor on the gearbox? Did you replace it yourself, was it difficult?

I've not had the speed sensor replaced, only the wheel sensors.

Is the speed sensor on the gearbox? Did you replace it yourself, was it difficult?

Oops, my bad. I meant the wheel speed sensor, my front left sensor wasn't sending anything to the ecu as the wiring had detached!

When the diagnostics machine was plugged it it immediately showed it wasn't getting valid data from the sensor. Once it was replaced & the diagnotics confirmed it was sending valid data I took it for a drive & all was well again. A mate had his done at a different garage & had to go back & have the replacement replaced as they hadn't seated it quite right so wasn't working properly & it ended up knackered.

I would definately get them to plug it in & confirm the new sensors are actually sending properly.

Had the Ford Dealership on the phone today, and it's booked back in on Tuesday for further diagnostics.

The chap I spoke to said it could be the pressure in the ABS module dropping, which would mean a new module...gulp!

He also said it could be the magnetic ring within the wheel bearing, which has maybe corroded, as was suggested above by iantt

not a betting man but im still saying bearing, ,or lets hope it is as its the cheaper option

Just an update on the problem I was having.

Had the car back into the local Ford Dealer, and after a lot od investigation it turns out it was indeed the ABS module that was at fault.

The module is split into 2 parts: a mechanical side and an electronic side. The fault on my car was with the mechanical side which houses the valves for the brake lines. Because of this no fault was being thrown up by the electronic side, and as a result no fault codes were stored and no lights were illuminated.

The constant clicking I could hear was the motor on the pump operating to build back up the pressure back up in the valve, which was leaking away.

The "block" as the call it came in at £182 + vat plus fitting - a lot cheaper than the whole module.

So, the issue is now resolved! Thanks to all those who replied!

Brian.