ABS Warning Light - Intermittent

[jameschong]

The ABS warning light has been appearing intermittently over the past few days.

It appears randomly, once or twice immediately after starting (i.e., it doesn't extinguish after pressure has been built up in the accumulator) and several times over the past few days, while driving. But in all cases, the Brake warning light doesn't come on - only the ABS warning light.

Turning the ignition on and then back on again extinguishes the warning light.

I replaced the accumulator last year, after it failed to hold pressure, causing the ABS and Brake warning light to flash if I braked suddenly. The problem has since disappeared.

Is it caused by a dirty sensor perhaps? It doesn't appear only when I brake - it doesn't seem to be correlated to braking.

Thoughts?

[Ezra]

Hi James,
I experienced similar symptoms; eventually linked it to 'high snow line' and 'rain' i.e. the sensor where it meets the magnet in the wheel hub had become frayed. As a result, water improved the connection; wiggling the wire to the sensor had the same effect. Changed the sensor (very easy) and its been fine since. I also checked the other sensor at the front and it too had frayed - changed that too and all is well.
Ez

[900t]

The "ANTI LOCK" light on its own indicates a fault in the ABS system, usually electrical fault. There is a procedure to short some pins with a paper clip at the ABS control unit that makes the ANTI LOCK light flash and it will tell you what is the stored code, like the check engine light.

[jameschong]

Originally Posted by Ezra

Hi James,
I experienced similar symptoms; eventually linked it to 'high snow line' and 'rain' i.e. the sensor where it meets the magnet in the wheel hub had become frayed. As a result, water improved the connection; wiggling the wire to the sensor had the same effect. Changed the sensor (very easy) and its been fine since. I also checked the other sensor at the front and it too had frayed - changed that too and all is well.
Ez

Hi Ez,

Turns out the right-front sensor wire had frayed to the point of breaking the connection. It's the one on the bottom, compared with a relatively newer one (left-front) I got from a half-cut c900 on the top of the picture.



You can clearly see the fraying at the base of the sensor. I checked the resistance and it was open.

I changed it (yes, a simple job) and the ABS warning light went off.

Interestingly, I initially pulled the ABS fault codes and it came out as 4444, 1241 (right front), 1311 (rear left). I suspect the faults had been around for a while but no one bothered to clear them (by cycling through the fault codes) after rectifying it and it's been there ever since.