ABS light on... and then off...

[Rob Bell]

Driving to the Brooklands Sprint on Saturday and I noticed that the ABS light remained on. Unusual, because the Bosch ABS 5.0 is usually bullet proof and rarely causes a problem. I re-started the car and the ABS light remained on for the remainder of the drive to Brooklands.

More oddly, the light extinguished itself during the competition and has not reappeared since.

I attached up the pscan and read the ABS ECU. A right-rear wheel sensor fault. I errased the code, and it did not return.

I drove the car in the live data mode, and all four wheel sensors returned realistic and comparable numbers.

An intermittent fault then.

Anyone else had the same?

I am going to see whether the fault returns - it could be either sensor-related or a problem with the reluctor ring on the drive shaft/stub axle, but would be interested to hear if anyone has encountered anything similar on an MGF? (I have had similar issues on a Freelander, but for some reason, that system is particularly sensitive to faulty sensors and corroded/ broken reluctor rings!)

[RobboMC]

I have had an intermittent ABS light come on and off a few times, and interestingly I've done a track day last month.

I expect however my light is due to the connection under the seat getting dislodged by my back side
rumbling around in the seat while on the track.

I'm off to the track this weekend so I'll see if it happens again,
though this one is more of a driver training center with concrete walls
so I'll not be driving with as much effort.

I don't have a pscan to find out the source of my light; probably should get one next.

[Rob Bell]

I'd definitely recommend one! So useful in circumstances like this.

If your seat is bringing a light on, it is probably the SRS rather than ABS?

[talkingcars]

.....I expect however my light is due to the connection under the seat getting dislodged by my back side
rumbling around in the seat while on the track. .....

But that would cause the SRS light, not the ABS light???

[RobboMC]

If your seat is bringing a light on, it is probably the SRS rather than ABS?

Ahhh yes, it's the red light so SRS.
It happened again this weekend, how can the SRS system know it's at a race track!!!

[Rob Bell]

My ABS error has returned, and this time, it isn't going away. Oddly, it was triggered by dropping a wheel into pot hole on the way to Prescott. Which was unfortunate, as I got speared into the armco when front wheel lock on an adverse camber. Only a mild dent in the front wing, so no disasater, but I needed to recalibrate my braking strategy as the havens opened and the track was soaking wet the whole day!

Got home. No signal from the right rear wheel sensor. I now need a bit of time to work out what when wrong and replace the sensor (assuming the sensor rather than the trigger wheel - and I think the intermittent initial presentation of the fault favours an electronic rather than a mechanical problem).

More soon!

[Rob Bell]

I attempted to remove a spare ABS sensor from a scrap hub and also the the ABS from the car - all to no avail. Despite swimming in penetrating oil, shocking with a hammer, applying heat (by adding weld to the screw head), nothing will budge either the screw holding the sensor from the scrap hub or from the car.

Epic fail.

Failure mode? Well, as it turns out, this is the sensor I had previously replaced myself after some rodent chewed its way through (read here: http://mgf.ultimatemg.com/project_shed/part6.htm) - but the reason why it failed was because the mechanic who changed the flywheel, clutch and gearbox for me, incorrectly routed the ABS sensor cable over the top of the upper suspension arm, so that the cable itself was being crushed between the arm and the bump stop on full compression (hence its sudden demise after fitting a pot hole on the way to Prescott).

Really: next time, I'll do this work myself... and then at least I'll only have myself to blame!!!