Noise and pulsing
 

Agreed to do a couple of tip runs for granddaughter today.First run went smoothly,returned to hers and loaded up for second run.On setting off again the first 4 applications of the brakes brought a "grinding" noise[but not like worn out pads on discs]wasn't constant-more as though something was catching a a given point as the wheels rotated.At the same time I could just feel a "pulsing" through the car and a definite pulsing of the brake pedal.After the first 4 applications the noise and the pulsing ceased and all was back to normal again.On setting back off from the tip the same thing happened again,but this time only for the first 2 applications of the brake after which it cleared again but this time the ABS light lit up and stayed on!! Looks like being Saturday before I'll have chance to get underneath to see if I can spot the problem,so in the meantime has anyone any ideas/thoughts on the issue?
Car is a P1 V70 2.4 n/a manual. TIA.

Sorry forgot to mention it sounds to be coming from N/S front.

Hello Dippydog

Maybe you are hearing the ABS kicking in? It sounds like a buzz.

You could rule it out by unplugging the power cable to the ABS module (between the battery and firewall).

I dont have a picture to hand, but the cable has about 4 wires and goes to half way down the front side of the ABS module and pump unit.

If it is kicking in when it doesn't need to, most likely is a faulty ABS wheel sensor. Also possible but slightly less likely is a faulty ABS module. Is the speedo behaving normally?

What year is your car?

I guess you don't have a code reader?

HTH
Steve

PS

This video from Robert DIY shows the two connectors to the ABS module

https://www.youtube.com/watch?v=0zV8nGeGukQ

Go to 3:24

For diagnosis, you don't need to undo the big connector, just remove the power connector and abs will no longer kick in.

Obviously the car wont have ABS protection while this is unplugged so do so at your own risk (and avoid skids or harsh braking).

I don't think there is a fuse that you can remove to achieve the same objective (but check your users manual/electrical diagrams).

Steve

Thanks for your replies. The car was first registered 1st January 2000 I've never heard the ABS kick in on any car I've had with it fitted as I've not needed to brake hard enough to operate it,so I don't know what it sounds like.The noise definitely sounds to be coming from N/S front-is that where ABS unit is?No I don't have any form of code reading equipment.

Sorry just re-read your first reply,my battery is directly behind the N/S headlight and in front of the air filter box[effectively sandwiched between the two].

Sorry yet again! Yes the speedometer was working as normal at all times

Classic symptoms of a corroded or cracked reluctor ring. Have a really good look at both rings at the front, if they're dodgy then replace them. They're cheap and apparently not too difficult to change, although I've not done it myself.

Oddly enough although I've never suffered such a failure before so I don't know the symptoms my first thought was the reluctor ring.I believe they're reasonably priced-I'll have to look that up-and just in case that's my problem I'll consult the bible according to St Haynes as to replacement procedure.

Try https://www.jandrcvjoints.co.uk/
I've used them and very good.