Weird ABS symptom

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alan s
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Weird ABS symptom

Post by alan s »

I said "symptom" because it's not really a problem.
I start the BX16V and all is normal. however, the ABS light doesn't go out. Drive down to the gate, hit the brake pedal and out it goes and the ABS works.
Other times, I drive out, get out to open the gate, drive through, stop to close it and as I take off the ABS light comes on then. I drive to the top of my road (700 metres) and as I stop at the main road, foot on brake pedal, off goes the light.
Silly part is, once it goes off, that's the way it usually stays and the ABS works as any BX16V ABS should.
Any thoughts anyone??


Alan S
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BernieLugg
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Post by BernieLugg »

Make sure you hit the brakes before its next "roadworthy"?! :shock:

Not sure, I would be checking the ABS sensors on the wheels to see if one is perhaps sticking / shorting. Are the ABS rings all in good condition?

If you park up without applying the handbrake - (leave it in gear) and then restart - does the problem occour then? If not it may be a front sensor or ring which is playing silly buggers.
pmhpmh
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Post by pmhpmh »

Can you also provoke the problem by varying the height of the car when sationary? I had an intermittent that was very random, but also braking and height dependent. If so it maybe that braking is causing suspension movement sufficent to aggravate a boken wire to a rear sensor. Very common fault.

To fault it can be time consuming until the fault becomes 'hard' enough to reproduce whilst the car is static.
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jeremy
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Post by jeremy »

I thought that if the thing was functioning properly, once the light came on it was supposed to stay on until the system was reset - ie by turning off and re-booting via the ignition key. I've had a couple of sensors fail (one preperly - needed new rear sensor and one from a frayed screen (front one) in a replacement section of cable that I hadn't routed very well. I think that when the front one failed it would sometimes re-set itself on the move as i remember being surprised when it happened.

If the computer can reset itself - I think you have a broken sensor lead (probably screen) - which is where the fun starts. I found mine (was looking for a back one and found the front one) by connecting the output to an old radio with a separate amplifier input and driving round listening to Radio ABS. In amongst the hums and bangs (bumps make a surprising difference) I could hear crackles - the dud sensor.

I see no reason why you shouldn't connect to a jack plug and use a casette recorder and listen afterwards. You don't need to drive far or fast to hear whats going on - and your gate would sound far enough.

Of course the brake pedal does have a function in the ABS system - normally the system is in check mode - but when you apply the brakes the system changes to active and monitoring mode - waiting to do its job. I suppose now when you release the pedal, the thing goes back to check mode, the connection is made due to different heights flexing the cable, the cumputer gets the messages its expecting and puts the light out and functions normally.

Just as a comment - I can't recall anyone finding a computer fault on the ABS system.


jeremy
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Post by RichardW »

I checked on the BX ABS wiring diagram this morning, and there should be a feed from the brake light swtich to the ABS computer. Dunno what it does with the signal, but my guess is yours is either there when it shouldn't be, or not there when it should be. Are the brake lights working properly??
Richard W
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