ABS Sensor Replacement
- Thread starter JHZR2
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The gunk to me looks like metal shavings. There's a magnet in there, so it will attract any stray ferrous metal. I wouldn't think there was enough there to cause a problem though. But I could be wrong--cleaning and reinstalling is easy enough to do.
Testing could be hard. I strongly suspect it's an IC, so the sensing element is interpreted and then a typical digital signal is generated. If you could probe the wires with everything hooked up, it could be fun to read the voltages and see what is going on. Is it 2 pins or 3 pins? You could always apply 12V through a 1k resistor to probe around, while measuring current, and take a guess as to which is VCC, GND, and output (if output exists). Edit: might need to drop to 500ohm once VCC is found, in case ICC is well above 6mA. But that might identify VCC at the least.
Testing could be hard. I strongly suspect it's an IC, so the sensing element is interpreted and then a typical digital signal is generated. If you could probe the wires with everything hooked up, it could be fun to read the voltages and see what is going on. Is it 2 pins or 3 pins? You could always apply 12V through a 1k resistor to probe around, while measuring current, and take a guess as to which is VCC, GND, and output (if output exists). Edit: might need to drop to 500ohm once VCC is found, in case ICC is well above 6mA. But that might identify VCC at the least.
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To me, judging just from the pics available, the top of the sensor looks to have some residual rust, I presume from the flange it sits on, and it has dirt stuck to the grease, I highly doubt it's metal, but who knows. But looking at the top of the flange, the hole for the screw is in perfect condition, no rust. So I can only guess, that water somehow can enter through the knuckle and from underneath, not from the top of the sensor.
IS the sensor bad, or will it function when you get all the ferrous material off of it?
I think the grease is probably just to prevent any water intrusion of the sensor if water gets into that area.
I have low speed false activation on my avalanche, i know the small sensor bolts are going to snap off. I may end up replacing the hubs.
I think the grease is probably just to prevent any water intrusion of the sensor if water gets into that area.
I have low speed false activation on my avalanche, i know the small sensor bolts are going to snap off. I may end up replacing the hubs.
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Originally Posted By: JHZR2
IMO the real question is what is the best way to test it?
Some can be tested with an Ohm meter 1000-2500 ohms other will require a scope. The Power probe with scope function I made a thread about will easily test this accurately enough to determine if its good or defective.
That one looks like it might be okay just a lot of metallic debris. This can come from rust flaking on the brake backing plate or tone wheel or iron content metallic pads (most).
This is common on some Euro cars with exposed sensors and metallic pads, Citroen XM and later C6 models were common for this ailment (IIRC the C6 sensor looked very similar to the BMW you have).
On the other hand I wouldn't jump through to may hoops for $40 either.
IMO the real question is what is the best way to test it?
Some can be tested with an Ohm meter 1000-2500 ohms other will require a scope. The Power probe with scope function I made a thread about will easily test this accurately enough to determine if its good or defective.
That one looks like it might be okay just a lot of metallic debris. This can come from rust flaking on the brake backing plate or tone wheel or iron content metallic pads (most).
This is common on some Euro cars with exposed sensors and metallic pads, Citroen XM and later C6 models were common for this ailment (IIRC the C6 sensor looked very similar to the BMW you have).
On the other hand I wouldn't jump through to may hoops for $40 either.
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