ABS & Serv lights after travelling above 50mph.

[aj40k]

[FONT=lucida grande, tahoma, verdana, arial, sans-serif]Hey there, my ABS and SERV light come on in my Clio (2002 1.2 16v) whilst driving at speed (50+), as soon as this happens the ABS kicks too early when it's not needed (Can feel it vibrating under the pedal.) and due to this the effectiveness of the breaking is greatly reduced.[/FONT]

[FONT=lucida grande, tahoma, verdana, arial, sans-serif]The car drives and brakes fine for any length of time below 50mph but as soon as I get to a dual carriage way etc the light comes on after a few seconds.[/FONT]

[FONT=lucida grande, tahoma, verdana, arial, sans-serif]I've taken it to multiple garages and they've all said it's an intermittent breaking error and that a diagnostic check doesn't detail what the error is.[/FONT]

[FONT=lucida grande, tahoma, verdana, arial, sans-serif]The only other advice I've been given is to take the car to a Renault dealership and have them run a diagnostic at the cost of £100, is there anything else I can try before doing this? I'm hesitant to shell out this much money as the Mechanic I spoke to at the dealership didn't seem confident that there machine would give any more information.

Thank you in advance.[/FONT]​

 

[sbridgey]

Checked the ABS rings?

 

[aj40k]

Yeah, I've had all the rings checked by mechanics who say they can't find any cracks or damage. The drivers side ring looks a bit tired (the teeth seem slightly warn) but none of the mechanics pointed this out as a possible cause.

Thanks for your reply.

 

[Sash]

Tbh, it sounds very much like a broken ABS ring, my bro has the exact same problem!

 

[aj40k]

Yeah, from everything i've found on the web it seems to be the common cause for the problem, that's why I've taken it to multiple garages to get it checked. It's very frustrating not being able to find the cause.

 

[northy]

I would say the air gap on the abs ring to sensor is too big.

Make sure the gap is set within tolerance and the rings are clean and rust free it should be fine again.

 

[northy]

Measure with a feeler gauge the gaps. The rears are larger than the fronts but use one side against the other to find the gap that's odd!

Rust wears the sensor down then when the ring is cleaned / changed the damage had been done wearing against the sensor and the sensor looses track of the ring at speed!

 

[aj40k]

I would say the air gap on the abs ring to sensor is too big.

Make sure the gap is set within tolerance and the rings are clean and rust free it should be fine again.

Hey, thanks.

How would I go about checking the air gap and finding out the tolerance and is it something I could adjust myself?

 

[northy]

Oh and if a ring is worn, change it.

My bet is a rear bearing has gone, caused wheel wobble that's resulted in the ring rubbing away the sensor ; )

 

[northy]

If the gap is larger on one side to the other (out of tolerance) change the ring and sensor to restore the correct gap!

Sensor cannot be reset unfortunately mate.

Let me know how u get on!

 

[aj40k]

Thank's a lot mate. One of the rear wheel bearings has recently been changed and the front drivers side ring looks more worn than the left. Trouble is i dont have the tools to take the rears brakes off and see if there is an obvious difference.

Also, the car was driven 100 miles on the motorway after the bearing being changed, with no error. This drive was to get its MOT. On the drive BACK from the MOT the problem started. Is there a part of the MOT process that could have caused the problem?

 

[northy]

U can check the gaps dead easy - get a feeler gauge from halfords. Take each wheel off and measure the gap by slotting in the gauge until it just starts to bite. Do it on all 4 wheels and record your results.