ABS light and hard brake pedal - help required!
 

Came out of work tonight to find my ABS light come on after a few minutes of driving. The brake pedal also seems harder when pressing than before. No funny noises that I could hear though.

Any ideas? Was only going a short distance so when I stopped I felt the brakes all round and the front drivers was the only one hot to touch, the others had a moderate heat on them as you would expect. Could it be something to do with this.

Hi mate, first check the fluid, if thats ok then apply your foot on the brake pedal and switch the car on, if the pedal goes down slightly then its not your servo, also check your brake pads and discs. do the following checks and if they are ok then check the abs sensors, if they are ok then it could be a sezized caliper.

Thanks for the reply.

Fluids are all okay and when I had a quick look earlier the discs and pads didn't look that bad.

Went out and tried pressing the brake pedal, turned the car on and it didn't move noticeably downward any further. Would there be noticeable movement when turning the car on?

It feels like the pedal goes stiff and stops long before it "touches the floor" like you expect to be able to do with a normally functioning brake pedal. Feels almost like it stops half way to where it should be able to be pressed.

Its too dark now to check the ABS sensors so will need to be tomorrow. Also, the ABS light is now on as soon as the car is started up.

Does it sound more like a siezed calliper or a component failure?

Pedal should sink a few mm when the engine is started, if it isnt then it could well be the servo has gone, after the engine has been running, does the pedal pump up solid? or is it constantly soilid.

Didn't feel like the pedal sank at all when started. When driving the pedal can be pressed, but it is just harder to press with less travel downwards.

If I pump the pedal with the engine running it doesn't solid up, but it remains stiff to press all the time.

Does sound like a servo problem.

Check the hose that runs from your intake manifold to the booster (black..cylindrical...on the driver side). There is a valve in it, to allow the booster to hold the vacuum even if the engine is shut off, allowing assistance for 1-3 stops. If the valve is clogged up, maybe there is no vacuum assistance = hard pedal.

Start the engine...let it run..switch off. Pull the vacuum hose off the booster...does the boost go "whooosh" and pull air in?

I'll check out the valve tomorrow for vacuum and report back.

Also meant to ask at the start, would a seized calliper cause the brake pedal to go stiff like it is?

Seems like the servo is the most locigal thing at the minute judging by everyones responses. Will see what results tomorrow brings and go from there I suppose.

Thanks for all the help so far folks.:thumb:

Edit.

Little update on this. Servo is working fine and none of the callipers are seized on.

Got a friend to scan the car and the only fault code showing up was something to do with the brake switch. He reset it and the ABS light stayed off for the last 2 days.

Yesterday the pedal went back to being normal with plenty travel and easy to press. This morning the pedal was heavy again and the ABS light has returned tonight. I've only got the spoiler brake light showing so will check both cluster bulbs tomorrow.

Starting to think these are both unrelated to one another. Brakes wise I think one of the brake pads (maybe even both rear pads) aren't fully retracting when the pedal is pressed and released, meaning the pad is sticking on the odd occasion and giving the heavy pedal. Maybe flexing the pad more than in-out movement?

ABS light I take it must be down to a faulty switch (dirty contacts or something).

What does everyone else think?

Are you any further forward on this ABS light problem?

Ive just had new discs/pads/lines/fluid fitted and now the ABS light is on all the time. Machinic said either its the synthetic brake fluid I had supplied or a ABS sensor as the car was up on a ram with wheels hanging down it may have pulled/broke one... His machine cant read ABS problems so I'll pop to main dealer see what it is.