BMW ABS WARNING LIGHT.

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Thu 24 Oct 2002 08:04
BMW ABS WARNING LIGHT. - Matt C
My wifes 1993 K reg BMW 316i has, for sometime now, had the ABS warning light illuminated on the annunciator panel. After taking it to the local 'BMW specialist' they explained that it is probably one of the wheel sensor, which they went on to say showed no obvious signs of damage. If I wanted to find out what the actual problem was I would have to take it to a BMW dealer and have it put on there computer (at the current cost of a BMW technicians time). I found some info on a website saying that BMW ABS problems are usually to do with a sticky ABS pump motor relay, wheel sensor or the ABS ECU (expensive). I have checked the relays and they seem to be fine. Does anyone have any knowledge on this matter, I would be grateful if anyone has
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Thu 24 Oct 2002 09:24
BMW ABS WARNING LIGHT. - nick
No experience of this car but you should be able to test the wheel sensors yourself. I've done this on a Rover 800 and it worked well. Enabled me to get a sensor from the scappy for £20 instead of £140 plus VAT from the dealer. I was able to test the scrappy one as well. You need a multimeter that will preferablably measure microvolts but you should be able to get away with millivolts. Jack up the wheel whose sensor you want to check. Trace back the wiring from the sensor until you come to the plug where it joins the loom. Disconnect this and stick the probes from the meter in the bit leading to the wheel, not the loom end. Spin the wheel and if the sensor is working you should see the meter give an intermittent reading. I used a millivolt meter and the needle just twitched very slightly. If no reading then the sensor is bust, but it might just need cleaning.
The sensors are just a magnet and coil positioned close to an iron toothed wheel on the hub. As the teeth go past the magnet as the wheel rotates a current is induced in the coil and this is fed to the ecu contolling the abs. (you could use an ammeter rather than a volt meter if you like). A build-up of metallic crap on the sensor magnet can occur so just cleaning this off may help. Hope this helps!
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Thu 24 Oct 2002 15:03
BMW ABS WARNING LIGHT. - Matt C
Cheers for that Nick. I'll give it a go, it may save me some money!
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