1999 3.0 Checking n ABS Sensor - BMW but any - hm
Hi all,

my ABS light and taction light have been on for some time.... in very cold weather sometime it goes off but but only for a second or two.

I took the motor today to my local indepant garage and they plugged her in to the computer... it spat out 2 faults

31 Speed Senor Front Right Suspension
32 Speed Senor Rear Right Suspension

(I'm in prague....so comm's is a little difficult, but the guy gave me the print out)

He also said it was not possible to clear the problems.

When we say right I mean right as you sit in the car...

I got the car home.. now the most simply test I know for an ABS sensor is to check if they are Open Circuit or not...

Checked the front right... open circuit.. happy days
Checked the rear right... open circuit.. happy days think I'm tracking down the problem.. just to be safe check the left side..

Front and Rear Open circuit.. okay.. now I'm mega confused... I know how to use a meter fine.. checked the meter is working etc... dunno.. not a clue..

I thought that the speedo also worked off the rear sensors? everything else works fine on the car accept the ABS/Traction (and of course the cruise control)

SO... has anyone had 4 x sensors go duff in one go? am I doing something STUPIDLY wrong?

I'm tempted to call the local dealer - (I presume that's how you meant to spell it?)tomorrow and have her checked there too....

Edited by Dynamic Dave on 27/01/2009 at 18:29

1999 3.0 Checking n ABS Sensor - BMW but any - Dynamic Dave
See if the following helps -

www.topbuzz.co.uk/maintenance/testing_abs/testing_...m
1999 3.0 Checking n ABS Sensor - BMW but any - elekie&a/c doctor
These sensors are known as "active sensors"and cannot be tested with ohm-meter.They are non-inductive and do not have any residual magnetism.They are Hall effect devices and run at around 6 volts.hth
1999 3.0 Checking n ABS Sensor - BMW but any - hm
Been a long time since I used HJ.... GREAT site..


Dear Sir, please humour me..

If I put my meter across the sensor should I not get any reading? I would have expected some kind of resistance. I get an open circuit...

I suspose I should have spun the disc's... errrr

I have already been on the top buzz site and was execting a reading from the meter.

Tomorrow now I will check them again and make some thin fly leads for the voltage test.
1999 3.0 Checking n ABS Sensor - Fault Found - hm
Okay, did some more digging and it appears that I needed to actually read the Ohms not use the open or closed function on the Fluke.

I chose to measure the reading from main plug on the ABS block to save pulling the wheels off etc (this would also give me a good indication that the wiring to the block was good)

Right Front Pins 15 & 16 = Open
Left Front Pins 12 & 28 = 18.65Mohms
Right Rear Pins 30 & 31 = Open
Left Rear Pins 13 & 29 = 19.01Mohms

This test has confirmed to me that the two sensors are duff.....as indicated by the garage OBDII computer. I plan to order two news ones asap.

Also worth noting... the Speedo gets her signal from the rear left sensor hence why it still appears to working even thou the ABS is playing up.

I will come back once I have new sensors with some closure to the thread.

Edited by hm on 27/01/2009 at 20:34

 

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