ABS activating when not braking ! - primera-taxi
I recently bought a W reg Primera at auction and am very pleased with it apart from an apparent ABS fault.
At low speed around 10 mph or less there is a whirring noise from under the bonnet followed by a ratcheting noise. The noise can appear when braking to a halt, when accelerating or when not touching the pedals at all. However if I'm touching the brake when the noise occurs I can feel the ABS system 'pulsing' when the ratcheting noise occurs.
The engine bay was filthy when I got the car home so I tried re-making the ABS pump / actuator earth. No difference; and the wiring pin looks OK. Do I have any choice other than letting my local Nissan dealer run a diagnostic check on the system.
ABS activating when not braking ! - Aprilia
Nissan agent would be the easiest route, obviously.

You could check the ABS pump relay, brake light switch (for sticking) and check the resistance of the wheel speed sensors (and give them a clean).
ABS activating when not braking ! - Deryck Tintagel
The activation could be due to a faulty sensor or tone wheel. You could try re-gapping the sensors from the tone (toothed) wheel on the hub but you will need to raise the wheel to check the whole circumference.

I would expect that a faulty sensor connection / ECU or excessive run-out on the tone wheel to cause a fault code
ABS activating when not braking ! - primera-taxi
I put the car into my local Nissan Dealer for an ABS diagnostic check ( £61 ) and the problem was diagnosed as a damaged (near side front)tone wheel. The tone wheel is an integral part of the CV joint and I will replace it with one from a breakers yard, soon.
My thanks to Deryck and Aprilia for their replies.
ABS activating when not braking ! - DL
I was going to mention the reluctor rings (on the CV joints) but it appears I'm a bit late!

A common problem on Rovers aswell.

groups.msn.com/honestjohn - Pictures say a thousand words.....
ABS activating when not braking ! - Deryck Tintagel
Good to hear that you are sorted.

Just added a profile: used to work on ABS electronics systems for HGV and this was one of the things we soon learnt to look for!

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