Method of checking wheel speed sensor fault

**LandyAndy** · 12th January 2008, 06:56 PM

Hi Guys
Chatting to my Bro the other nite about my 3 amigos problem.
He said he has a stuffed(due to prang) falcoon hub with ABS sensor still attached.
He put his multi meter on it and found that it registers a static ohms value which changes when you rotate the hub.On a win here I thinks!!! I consulted the RAVE CD.Found that the D2 should register 950-1100 ohms resistance on the wheel sensors.All mine were slightly above the 1100 ohms static but not by mutch.BUGGER as I was hoping to find 1 open circuit!!!.
Did the test again,this time turning each wheel and registering the ohms,definately fluctuated heaps for each wheel as the wheel turned then settled to the start value.This tells me my wheel sensors are OK.
Im ready to do the same check on the SLABS ECU but I would like to see if you 2 that have the same problem at the moment get the same result or different(PM coming).
My next check is to test the readings at the SLABS,got all the info from RAVE but would love to hear at least one of you that you find a fault/no faults in a wheel sensor via the first method before I proceed.
Im not going to do any further tests to you 2 get in touch!!!!
Just hoping to draft out variables,the tests Ive done sofar wont hurt your ECUs.
Please try asap!!!!
Andrew

**Lucus** · 12th January 2008, 07:02 PM

Did you check for a voltage fromt he sensor while you rotated the wheels?

Edit: Im an idiot. You can't test voltage in a 2 wire speed sensor. Is your brother able to test frequency with his multimeter?

For what its worth my 93rrc had ongoing abs and tc faults codes IE wheel sensor air gap to big, brake pedal position sensor error. I check and readjusted and check again and keep getting the same faults. I was also getting codes popping up that wherent on the list. I read on the net about replacing the abd ecu and pump relay and i did that all cleared the codes and they havent been back in almost 12 months

**Blknight.aus** · 12th January 2008, 08:06 PM

to save a little time and effort grab a patch of gravel and when the tc/abs/hdc combo is on hit it at a medium sort of pace and then peg the anchors... Abs will work on the 3 remaining wheels or on the axle that doesnt have the ABS fault depending on which ABS brain you have....

Big red is having intermittnat ABS/TC warnings and its the front right wheel Rover com says so and funnily enough thats the one that locks when I get into the brakes hard enough....

**LandyAndy** · 12th January 2008, 08:51 PM

Dave my ABS TC and HDC lights are on.
Hoping the others with the same prob can eliminate my probs by working thru my findings
Andrew

**Blknight.aus** · 12th January 2008, 08:58 PM

dont forget that the sensor fault may not be the sensor but the harness and plugs prior to the sensor.. Big reds Im fairy certain is in the loom as I can make the fault appear at will by grabbing the wiring and giving it a shake while the ignition is on.

**LandyAndy** · 13th January 2008, 06:16 PM

I did the skid test,found that the right rear skided.
OK decided to clean that sensor again,jacked up the rr with the trolley jack pushed the garden hose up where the sensor wire goes and turned the wheel whilst the water was running.Started the car up eased it into gear,speedo works!!!!.
Then repeated the same on the left rear,NO SPEEDO!!!!! found the culprit,the left rear sensor or a wiring fault for the left rear sensor.The fronts both made the speedo work.
The speedo reads 120kmh at idle in fith!!!!!.Confused!!!!
Andrew

**Blknight.aus** · 13th January 2008, 06:48 PM

that sounds like a dud sensor, the computer averages out the wheel speeds to get vehicle speed and ignores any that are obviosuly telling fibs.

If you can get hold of a meter that can impersonate a cro use that and compare a good sensor to the bad one...

**LandyAndy** · 13th January 2008, 07:32 PM

All 3 that worked gave the same speed reading.
Andrew

**Blknight.aus** · 13th January 2008, 07:56 PM

ok lets try wording that differntly (my bad)

With the vehicle off of the deck spin up a wheel and then using a CRO look at the output of the sensor.

Then compare good to bad... (you'll be looking at the wave output of the sensor not what the speedo indicates)

**Pedro_The_Swift** · 17th January 2008, 05:08 PM

hm,, ok.

just the fact that the speedo doesnt work for THAT wheel is not enough?

gotta buy a trolley jack

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