[Brakes] ABS

[Sparki]

Hi all
I have just signed up on here, not really good with motors and rely on mechanics, how ever, your advise would be really be appreciated.
 i have a citroen berlingo 11 plate 1600 diesel. My front abs light is constantly on, but only after setting off, engine on no light set off  then light on, i had the sensors changed by national tyres 9 months ago yet the light still comes on and the meter says sensors, when i set off there is a grinding noise from the drivers side front then after that the light come on and it drives fine, at times the break pedal is very hard to press on setting off.

Please can you help or advise, BCC have looked and said sensors but they have been changed, any ideas welcome.

[Tomcat3]

Hi Sparki welcome to the forum, from previous posts on the forum it usually is the connector that the sensor plugs into or the wiring where it is held by a clip nearby. Have a search on the forum. The grinding doesn't sound good something is rubbing on the disc ie pads worn out or stone stuck in caliper.

[Sparki]

Hi Sparki welcome to the forum, from previous posts on the forum it usually is the connector that the sensor plugs into or the wiring where it is held by a clip nearby. Have a search on the forum. The grinding doesn't sound good something is rubbing on the disc ie pads worn out or stone stuck in caliper.

Hi Tomcat
Thankyou for your reply. I will have a look tomorrow, never seen a clip, so this i will find and look at the wires. No stone or worn discs or pads, both sensors were said to be gone? no one understands it that ive taken it to.   iiiIt was said the grinding was the ABS coming on?

[Lighty]

A common cause of this is the air gap between the tip of the sensor & the magnetic strip seal on the wheel bearing.
A slightly too large gap causes an irregular signal, so the abs thinks it need to work .
I would take a close look at the ring on the bearing for dirt or damage, even a small Nick in it will cause this.
Also check very carefully that the sensor is not sitting on corrosion as this can bend it away from the ring.

[Sparki]

A common cause of this is the air gap between the tip of the sensor & the magnetic strip seal on the wheel bearing.
A slightly too large gap causes an irregular signal, so the abs thinks it need to work .
I would take a close look at the ring on the bearing for dirt or damage, even a small Nick in it will cause this.
Also check very carefully that the sensor is not sitting on corrosion as this can bend it away from the ring.

Excellent point. Do you feel new brake calipers could be needed? 
Ive been to three garages, no one had any answers apart from sensors, which have been changed. BCC the dealer quoted silly money to replace them.
A big thank you, really is appreciated. Tomorrow iam going to have a good look at all point raised.

[GraemeT]

Hi - calipers sit independent to/from the ABS setup - so if you're sure it is the sensors then the answer would be no - check the hub and the ABS ring first.

We've just chased down a similar problem on the Mini (same engine, different braking setup so the solution maybe different) that was reporting front left and right sensor problems. Traced that back to water in the multi plug that goes into the BMW ABS unit- but only after changing both sensors. £5 worth of contact cleaner and ten minutes with a hair dryer fixed that  - so it may be worth seeing where the wiring from your ones go and double checking that the loom and plugs are trouble free.

[GraemeT]

p.s. turns out you may have the same ABS unit as the Mini - Bosch  (below) - mutiplug on the left of the picture can suffer from water ingression


 

[Sparki]

Hi - calipers sit independent to/from the ABS setup - so if you're sure it is the sensors then the answer would be no - check the hub and the ABS ring first.

We've just chased down a similar problem on the Mini (same engine, different braking setup so the solution maybe different) that was reporting front left and right sensor problems. Traced that back to water in the multi plug that goes into the BMW ABS unit- but only after changing both sensors. £5 worth of contact cleaner and ten minutes with a hair dryer fixed that  - so it may be worth seeing where the wiring from your ones go and double checking that the loom and plugs are trouble free.

Hi Graeme T
Thanks for your advise, changed both sensors left side clear now, right side bearings changed which has a ring to it also a counter ring which if a crack is present can cause the fault, ABS light stays on permanently now, how ever the plug under the wheel arch seems to be hard to get a reading off, left 6.16
right up and down but once a good contact made 6.14, so both seen to match, i feel it may be the plastic plug, how ever will be looking for the BMW ABS plug.
The grinding and pedals not working has now stopped with the new bearing in the left side, that was scary!
Thanks for your advise.
Bearings took the mechanic 3 hours, if it is the plug took me 5 mins, i will be happy though if it is. Pay to be a spark at last.
Also thanks for the picture

Thankyou so much.

Dave