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Right now my speedometer is inop, ABS light is on, as well as spoiler light. Based on reading, it seems highly likely that this is a faulty ABS speed sensor causing this.
My question however is that before I start replacing them ($120 ea), how could I tell which one is bad? Are there four, one on each hub?
Do you have a multi-meter and test the resistance/continuity of each sensor? Simple to do. Remove the wheel, disconnect the sensor connector and measure...
Do you have a multi-meter and test the resistance/continuity of each sensor? Simple to do. Remove the wheel, disconnect the sensor connector and measure...
I do have a multimeter.
I wanted to originally pull the sensors, but I hear they often get either stuck or the bolt snaps, was hoping to avoid this if possible
I don't think you need to pull the sensor from the carrier to test it unless you want to clean it. Just disconnect the sensor connector (located inside the black plastic cylinder) from the wiring harness and test the sensor while in the carrier. My sensors came out quite easily though. There is a small hex bolt that keeps them in and was hand tightened.
I do know one of my brake wear sensors is bad - do they share the same circuit? Would that be reason for the light?
On my car I made a jumper out of the existing sensors' pigtail and tied the jumpers out of the way on the struts. Seeing that the brakes get inspected by the state here in VA every year and I have cause to have the tires off from time to time I just rely on visual inspection of the pads and avoid the annoyance of dealing with the sensors.
I suspect I am not alone in this.
Andy
ABS works. All Speed sensors ohm at ~1700., If there was any fault the ABS would not work. The light flickers and one can feel the ABS working when active.
Not sure how but I am sure there is a test to see if the speedometer is getting a signal. I would think if an oscilloscope was attached to its connection it would display speed pulses.
spoiler light turned on. Likely completely unrelated.
The OBC does not receive a speed signal either.- how did you determine this?
When I use Durametric software and cable I believe one of the running data items is speed suggesting that the Motronic ECU has this data available to it.
What does that indicate?
In addition to my notes above, I would do the non-diagnostic simple stuff first:
Clean all the connectors involved with spray electronics cleaner.
Follow any ground wires, usually a brown wire or brown with a stripe on the pigtails and verify that the ground connection is not loose.
ABS works. All Speed sensors ohm at ~1700., If there was any fault the ABS would not work. The light flickers and one can feel the ABS working when active.
Not sure how but I am sure there is a test to see if the speedometer is getting a signal. I would think if an oscilloscope was attached to its connection it would display speed pulses.
spoiler light turned on. Likely completely unrelated.
The OBC does not receive a speed signal either.- how did you determine this?
When I use Durametric software and cable I believe one of the running data items is speed suggesting that the Motronic ECU has this data available to it.
What does that indicate?
Does anyone know how to test the speedo with an oscilloscope? Picked up one from amazon that's arriving today so I can test this.
Spoiler light activates with speed, no speed reading means there would be a fault. Spoiler can still be retracted up and down manually - based on having googled this issue, it's definitely related.
OBC receives speed signal from Speedometer, which gets it from the ABS ECU.
06-18-2018, 11:27 AM
Wheel Speed Sensor - Which one is bad?
