I dropped the rear coil over units yeaterday to adjust the Konis, and had inadverdently left the ignition switch on. As you may know, dropping the rear units can cause some degree of tugging on the rear ABS sensor line. Anyway, when I got it back together, the ABS, DSC, and tire pressure monitor lights are all on. I have checked to make sure I didn't unplug the sensors, and a casual observation shows everything is OK. I did have to struggle with one of the ABS lines to get it back in the clip on the shock and am fearing I may have broken the wire internally.

Any ideas? How can I clear the lights assuming everything is OK?

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Does the checklight go off after a hard reset? (unpluggin your battery)??

 

Yes, the lights remain on after battery disconnect/reconnect

 

Provided that you did not damage the wires, all you need to do is drive greater than 15kph (~10mph). The MINI ABS system abides by ECE13 requiring that a series of tests are completed before resetting the fault. Pulling the battery will not do anything since these faults are typically in EEPROM (requires the controller to reset the fault not from battery backup). This is different than many engine controllers. Most likely you disconnected the wheelspeed sensor which sets a fault pretty quickly (usually under 1 second). If driving off does not fix it, you probably have a disconnect.

To troubleshoot keep the sensor connected (try to get some wire in to do measurements. I have not checked but I believe MINI uses Active wheelspeed sensors. This means they get power and ground from the ABS unit and send back a signal pulse. If you have access to a digital mulimeter you should be able to check for power to the sensor with the key in the on position. With the key in the on position, measure the voltage between the different connector pins. Wheelspeed sensors vary a little, but typically they are powered by 5 volts. If you slowly turn the wheel, you should see one of the connector pins toggle between two voltages and stay at one once the wheel is no longer moving. The between any two pins you should never have 0 volts. If you do, the sensor or connector is shorted or broken.

I'll see if I can find some better descriptions tomorrow at work. Unfortunately, I will not get exactly the MINI sensors, but I should have something very close.

 

Thanks for the input. Driving definitely does not reset as I drove for 50 miles at speeds up to 60 mph. I'll try reading the voltage at the ABS connector as you suggested.

The more I think about it, the more I think it would have been very difficult to damage the wire internally. I only wrestled with the rubber gromet, amd that wire seems to be pretty well armored. I probably did some damage at the hub connector. There is a memebr of BAMA (Birmingham Area MINI Association) that is a BMW mechanic with his own shop. I'll take the car to him if I can't diagnose/fix in the next day or two.

 

Ok, I checked with our sensor expert. I was thinking of a different sensor so ignore the first troubleshooting.

The sensor is two-wire. power and signal. It's a current interface so you need to load the signal down to test the sensor.

Keep the sensor on the vehicle and disconnect the ecu from the connector.
You can use a 9 volt battery to power the sensor without damaging it.
The hard part will be to determine the power versus the signal side.

You will need, 9v battery, 115 ohm resistor, and a voltmeter. The resistor is your load to measure the sensor signal. The 9 volt is to power the sensor.

Connect as follows:


Measure the voltage across the resistor. It should read around 0.8V or 1.6V depending on the wheel's position. slowly turn the wheel and it should switch between these states. If it doesn't, swap the two signals (power and signal are probably reversed). If it reads 0V, the sensor is shorted or broken. If it read much over 1.6V (like 8v or so) the sensor is damaged.

If the sensor is ok, but you still have a fault, you may have a problem between the ABS unit and the sensor.

 

Thanks. I'll try it and let you know what I find.

 

The problem has been traced to an internal short in the sensor wire. The clips that hold the ABS wire and the brake line on the Koni's are VERY tight. Wrestling with one of them caused the internal short.

I strongly recommend that anyone installing Koni's open the clips up by filing or by spreading before installation.

BTW the Koni's are that extra little bit when you are looking for the last of the 9/10ths in stock handling.

Thanks Mattcoon for your help!

 

>>The problem has been traced to an internal short in the sensor wire. The clips that hold the ABS wire and the brake line on the Koni's are VERY tight. Wrestling with one of them caused the internal short.
>>
>>I strongly recommend that anyone installing Koni's open the clips up by filing or by spreading before installation.
>>
>>BTW the Koni's are that extra little bit when you are looking for the last of the 9/10ths in stock handling.
>>
>>Thanks Mattcoon for your help!
No problem. BTW. I updated the drawing to help understand what I meant with the circuit. When I talked to our Whees Speed Sensor expert he chuckled a little and said, "You know, we don't design the wires to hold a suspension." Glad it worked out for you.

 

What did you do to repair the internat short?

 

Hi: I'm new to this forum. I can't seem to open up the image on how to set up the 9 volt battery and 115 ohm resistor to check the abs sensor. Can you please forward it to me. Thank you.